Tuesday, April 29, 2008
Source : http://www.brunei-online.com/
Monday, April 28, 2008
BANGALORE (AFP) An Indian rocket blasted off and successfully launched a cluster of 10 satellites in a single mission Monday, marking a milestone for the country's 45-year-old space programme.
The PSLV rocket lifted off at 9:20 am (0350 GMT) from the Sriharikota space station in southern
"The mission was perfect," G. Madhavan Nair, chairman of the Bangalore-based Indian Space Research Organisation (ISRO), said after the launch telecast live by the public broadcaster Doordarshan. "Team ISRO has done it again."
"It is a historic moment for us because it is the first time that we have launched 10 satellites in a single mission," he added, congratulating Indian scientists who broke out into applause at the mission control centre.
The rocket's unprecedented payload included an Indian remote-sensing satellite known as the Cartosat-2A, a mini satellite and eight so-called nanosatellites developed by foreign research institutions, including those from
The satellites were deployed in orbit within minutes of each other in a rare space feat, with the entire mission lasting about 20 minutes.
Source : http://afp.google.com/
Setting a world record, India’s Polar rocket on Monday successfully placed ten satellites, including the country’s remote sensing satellite, into orbit in a single mission.
The ten-pack launch of the Indian Space Research Organisation saw the 230-tonne Polar Satellite launch Vehicle carry the heaviest luggage–824 kgs–and put into orbit an Indian Mini Satellite and eight foreign nano satellites besides the Cartosat-2A remote sensing satellite.
At the end of the 52-hour countdown, the PSLV-C9, with a lift-off mass of 230 tonne, blasted off from the launch pad at the Satish Dhawan Space Centre and soared into the clear sky in a textbook launch at 9:23 am.
Fourteen minutes after lift off, the fourth stage of the ISRO’s workhorse launch vehicle, in its 13th flight, injected the ten satellites, into the 635 km polar Sun Synchronous Orbit.
This is for the first time that ISRO has put ten satellites in orbit in a single launch. This is also the PSLV’s twelfth successful flight.
It is for the first time in the world that ten satellites were launched in a single mission. Russia [Images] had earlier launched eight satellites together.
Besides the 690 kg Indian remote sensing satellite CARTOSAT-2A and the 83 kg Indian Mini Satellite, the rest eight Nano Satellites were from abroad.
This is the third time that the PSLV has been launched in the core alone version, without the six solid propellant first stage strap-on motors.
Terming the launch satisfactory, ISRO Chairman G Madhavan [Images] Nair said, “All parameters worked wonderfully well.”
“It is a proud moment for ISRO as it put 10 satellites into the orbit in a single launch and I am extremely proud of the entire team,” Nair said.
He said that initially there was some anxiety about the weather conditions but everything went well.
Mission Director Dr Kosy said the launch proved that the PSLV was dependable and capable. “This has proven that the PSLV can be depended upon and that puts more responsibilities for us in the upcoming Chandrayan mission,” Kosy said.
CARTOSAT-2A, which was put in orbit by PSLV-C9, is the latest state-of-the-art remote sensing satellite weighing 690 kg, carries a Panchromatic Camera capable of taking black and white pictures in the visible region of electromagnetic spectrum. It would be used for mapping purpose and management of natural resources.
The IMS-I, developed by ISRO for a remote sensing, has two optical payloads–a mutispectral camera (Mx Payload) and a Hyperspectral Camera (HySI Payload), which would operate in the visible and near infrared regions of the electromagnetic spectrum.
The satellites, with a total weight of appriximately 50 kg, were built to develop nanotechnologies for use in satellites and for the development of technologies for satellite applications.
Sunday, April 27, 2008
As temperatures rise, the sea will absorb heat from the atmosphere, causing it to expand and therefore creating sea level rises.
Although ice sheets in Greenland and Antarctica could be affected by warming temperatures, it isn’t thought that they will melt significantly enough to contribute to sea level rises. If they melt over the coming one thousand years, though, due to increased temperatures, oceans could increase in depth by a number of metres. Land glaciers will continue to melt over the coming century which will increase the level of the seas.
The IPCC have stated increases for the 2080’s of from 9cm to 48cm in the ‘Low Emissions Scenarios’. This rises to 16cm to 69cm in the ‘High Emissions Scenarios’.
Some islands will be affected by sea level rises significantly and their habitats will be threatened. One example is of the small island - Tuvalu in the Pacific, which is already experiencing severe flooding which is damaging their homes and affecting their drinking water. The islanders have already started to leave and the rest will have to do so in coming years if the trend continues.
Saturday, April 26, 2008
What is the geological time scale?
Historical records only go back a few thousand years, and are inadequate to treat most geological processes. To understand the timing of geological processes we need to look at the geological rock record. This includes erosion, mountain building and other geological events. Over hundreds to thousands of millions of years, continents, oceans and mountain ranges have moved vast distances both vertically and horizontally. Once-deep oceans hundreds of millions of years ago now occupy mountainous desert regions of the Earth.
How is it measured?
The earliest geological time scales simply used the order of rocks laid down in a sedimentary rock sequence (stratum) with the oldest at the bottom. However, a more powerful tool was the fossilised remains of ancient animals and plants within the rock strata. After Charles Darwin's publication Origin of Species (Darwin himself was also a geologist) in 1859, geologists realised that particular fossils were restricted to particular layers of rock. This built up the first generalised geological time scale.
Once formations and stratigraphic sequences were mapped around the world, sequences could be matched from the faunal successions. These sequences apply from the beginning of the Cambrian period, which contains the first evidence of macro-fossils. Fossil assemblages 'fingerprint' formations even though some species may range through several different formations. This feature allowed William Smith (an engineer and surveyor who worked in the coal mines of England in the late 1700s) to order the fossils he started to collect in south-eastern England in 1793. He noted that different formations contained different fossils and he could map one formation from another by the differences in the fossils. As he mapped across southern England, he drew up a stratigraphic succession of rocks although they appeared in different places at different levels.
By matching similar fossils in different regions throughout the world, correlations were built up over many years. Only when radioactive isotopes were developed in the early 1900s did stratigraphic correlations become less important as igneous and metamorphic rocks could be dated for the first time.
Geological Time ScalePDF (28 kb)GIF (43 kb)
Divisions in the geological time scales still use fossil evidence and mark major changes in the dominance of particular life forms. The Devonian Period is known as the age of fishes, as fish began to flourish at this stage. However, the end of the Devonian is marked by domination of a different life form, plants, which marks the beginning of the Carboniferous Period. The different periods can be further subdivided (e.g. Early Cambrian, Middle Cambrian and Late Cambrian).
The Precambrian Era is the time span from the beginning of the Earth at approximately 4.5 billion years ago up until 570 million years ago. It is subdivided into the Early Archaean and later Archaean and Proterozoic Eras.
The Palaeozoic Era follows the Precambrian, covering the Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian Periods, ranging from 570 million years up to 225 million years ago.
The Mesozoic Era (covering the Triassic, Jurassic and Cretaceous Periods) spans the age range of 225 million years up to 65 million years.
The Cenozoic Era covers the last 65 million years up to the present. The Cenozoic is split into several Epochs, the Palaeocene, Eocene, Oligocene, Miocene, Pliocene, Pleistocene, and Holocene, with the Quaternary Period covering the last 2 million years.
A graphic way to represent the Eras and Periods is like a 24-hour time clock. The Precambrian Era goes from 12 midnight to 20 minutes past 10 the next evening. The time span from our earliest relatives (the Australopithecines - some 3.5 million years ago) to Homo sapiens covers less than a second on our 24 hour clock.
Faunal succession: is the time arrangement of fossils in the geological record.
Formations: are stratigraphic successions containing rocks of related geological age that formed within the same geological setting.
Ga: is an abbreviation used for billions (thousand million) of years ago.
Geochronology: is the study of the age of geological materials.
Ma: is an abbreviation used for millions of years ago.
Palaeobiology: is the study of the evolution of life during geologic time.
Palaeobotany: is the study of ancient plants.
Palaeontology: is the study of ancient lifeforms.
Stratigraphic succession: is a sequence of layered sedimentary rocks.
What is radioactive dating?
Radioactive dating is a method of dating rocks and minerals using radioactive isotopes. This method is useful for igneous and metamorphic rocks, which cannot be dated by the stratigraphic correlation method used for sedimentary rocks.
Over 300 naturally-occurring isotopes are known. Some do not change with time and form stable isotopes (i.e. those that form during chemical reactions without breaking down). The unstable or more commonly known radioactive isotopes break down by radioactive decay into other isotopes.
Radioactive decay is a natural process and comes from the atomic nucleus becoming unstable and releasing bits and pieces. These are released as radioactive particles (there are many types). This decay process leads to a more balanced nucleus and when the number of protons and neutrons balance, the atom becomes stable.
This radioactivity can be used for dating, since a radioactive 'parent' element decays into a stable 'daughter' element at a constant rate. The rate of decay (given the symbol λ) is the fraction of the 'parent' atoms that decay in unit time. For geological purposes, this is taken as one year. Another way of expressing this is the half-life period (given the symbol T). The half-life is the time it takes for half of the parent atoms to decay. The relationship between the two is: T = 0.693 / λ
How is it measured?
Many different radioactive isotopes and techniques are used for dating. All rely on the fact that certain elements (particularly uranium and potassium) contain a number of different isotopes whose half-life is exactly known and therefore the relative concentrations of these isotopes within a rock or mineral can measure the age. For an element to be useful for geochronology (measuring geological time), the isotope must be reasonably abundant and produce daughter isotopes at a good rate.
Either a whole rock or a single mineral grain can be dated. Some techniques place the sample in a nuclear reactor first to excite the isotopes present, then measure these isotopes using a mass spectrometer (such as in the argon-argon scheme). Others place mineral grains under a special microscope, firing a laser beam at the grains which ionises the mineral and releases the isotopes. The isotopes are then measured within the same machine by an attached mass spectrometer (an example of this is SIMS analysis).
What dating methods are there?
Radiocarbon (14C) dating
Rubidium-Strontium dating (Rb-Sr)
Potassium-Argon dating (K-Ar)
Argon-Argon dating (39Ar-40Ar)
Rhenium-Osmium (Re-Os) system
Uranium-Lead (U-Pb) system
The SHRIMP technique
Fission track dating
Radiocarbon (14C) dating
This is a common dating method mainly used by archaeologists as it can only date geologically recent organic materials, mainly charcoal, but also bone and antlers.
All living organisms take up carbon from their environment including a small proportion of the radioactive isotope 14C (formed from nitrogen-14 as a result of cosmic ray bombardment). The amount of carbon isotopes within living organisms reaches an equilibrium value, on death no more is taken up, and the 14C present starts to decay at a known rate. The amount of 14C present and the known rate of decay of 14C and the equilibrium value gives the length of time elapsed since the death of the organism.
This method faces problems because the cosmic ray flux has changed over time, but a calibration factor is applied to take this into account. Radiocarbon dating is normally suitable for organic materials less than 50 000 years old because beyond that time the amount of 14C becomes too small to be accurately measured.
Rubidium-Strontium dating (Rb-Sr)
This scheme was developed in 1937 but became more useful when mass spectrometers were improved in the late 1950s and early 1960s. This technique is used on ferromagnesian (iron/magnesium-containing) minerals such as micas and amphiboles or on limestones which also contain abundant strontium. However, both Rb and Sr easily follow fluids that move through rocks or escape during some types of metamorphism. This technique is less used now.
Potassium-Argon dating (K-Ar)
The dual decay of potassium (K) to 40Ar (argon) and 40Ca (calcium) was worked out between 1921 and 1942. This technique has become more widely used since the late 1950s. Its great advantage is that most rocks contain potassium, usually locked up in feldspars, clays and amphiboles. However, potassium is very mobile during metamorphism and alteration, and so this technique is not used much for old rocks, but is useful for rocks of the Mesozoic and Cenozoic Eras, particularly unaltered igneous rocks.
Argon-Argon dating (39Ar-40Ar)
This technique developed in the late 1960s but came into vogue in the early 1980s, through step-wise release of the isotopes. This technique uses the same minerals and rocks as for K-Ar dating but restricts measurements to the argon isotopic system which is not so affected by metamorphic and alteration events. It is used for very old to very young rocks.
The decay of 147Sm to 143Nd for dating rocks began in the mid-1970s and was widespread by the early 1980s. It is useful for dating very old igneous and metamorphic rocks and also meteorites and other cosmic fragments. However, there is a limited range in Sm-Nd isotopes in many igneous rocks, although metamorphic rocks that contain the mineral garnet are useful as this mineral has a large range in Sm-Nd isotopes. This technique also helps in determining the composition and evolution of the Earth's mantle and bodies in the universe.
Rhenium-Osmium (Re-Os) system
The Re-Os isotopic system was first developed in the early 1960s, but recently has been improved for accurate age determinations. The main limitation is that it only works on certain igneous rocks as most rocks have insufficient Re and Os or lack evolution of the isotopes. This technique is good for iron meteorites and the mineral molybdenite.
Uranium-Lead (U-Pb) system
This system is highly favoured for accurate dating of igneous and metamorphic rocks, through many different techniques. It was used by the beginning of the 1900s, but took until the early 1950s to produce accurate ages of rocks. The great advantage is that almost all igneous and metamorphic rocks contain sufficient U and Pb for this dating. It can be used on powdered whole rocks, mineral concentrates (isotope dilution technique) or single grains (SHRIMP technique).
The SHRIMP technique
Zoned zircon grain
The SHRIMP (Sensitive High Resolution Ion MicroProbe) technique was developed at the Research School of Earth Sciences, Australian National University, Canberra in the early 1980s. It has revolutionised age dating using the U-Pb isotopic system. Using the SHRIMP, selected areas of growth on single grains of zircon, baddeleyite, sphene, rutile and monazite can be accurately dated (to less than 100 000 years in some cases). This technique not only dates older mineral cores (what we call inherited cores), but also later magmatic and/or metamorphic overgrowths so that it unravels the entire geological history of a single mineral grain. It can even date nonradioactive minerals when they contain inclusions of zircons and monazite, as in sapphire grains. The SHRIMP technology has now been exported to many countries such as the USA, France, Norway, Russia, Japan and China. It can help fix the maximum age of sedimentary rocks when they contain enough accessory zircon grains (usually need about 100 grains).
Because of advancements in geochronology for over 50 years, accurate formation ages are now known for many rock sequences on Earth and even in space. The oldest accurately dated rocks on Earth are metamorphosed felsic volcanic rocks from north-west Western Australia. These were dated at about 4.5 billion years old using single zircon grains on the SHRIMP.
Fission track dating
Mt Warning zircon. Photo: Geotrack International.
Several minerals incorporate tiny amounts of uranium into their structure when they crystallise. The radioactive decay from the uranium releases energy and particles (this strips away electrons leading to disorder in the mineral structure). The travel of these particles through the mineral leaves scars of damage about one thousandth of a millimetre in length. These 'fission tracks' are formed by the spontaneous fission of 238U and are only preserved within insulating materials where the free movement of electrons is restricted. Because the radioactive decay occurs at a known rate, the density of fission tracks for the amount of uranium within a mineral grain can be used to determine its age.
To see the fission tracks, the mineral surface is polished, etched with acids, and examined with an electron microscope. An effective way to measure the uranium concentration is to irradiate the sample in a nuclear reactor and produce comparative artificial tracks by the induced fission of 235U.
Fission track dating is commonly used on apatite, zircon and monazite. It helps to determine the rates of uplift (for geomorphology studies), subsidence rates (for petroleum exploration and sedimentary basin studies), and the age of volcanic eruptions (this is because fission tracks reset after the eruption). However, care is needed as some samples have fission tracks reset during bushfires, giving far too young ages. Fission track dating is mostly used on Cretaceous and Cenozoic rocks.
The atomic number of an element is given by the number of protons present within the element's nucleus, and this helps determine the chemical properties of that element.
The atomic mass of an element combines the number of protons and neutrons within its nucleus.
The atomic weight of an element is the average relative weight (mass) of atoms and can vary to give different isotopic members of the element.
Isotopes are atoms with the same atomic number (i.e. protons) and have different atomic masses (i.e. number of neutrons).
For example, the element potassium (represented by the symbol K) has three isotopes:
Relative abundance in nature
The numbers 39, 40, and 41 are the mass numbers. As all three isotopes have 19 protons, they all have the chemical properties of potassium, but the number of neutrons differs: 20 in 39K, 21 in 40K, and 22 in 41K. Potassium has an atomic weight of 39.102, close to the mass (39) of its most abundant isotope in nature (39K).
Dickin, A.P., 2000. Radiogenic isotope geology. Cambridge University Press, 490p.
York, D., and Farquhar, R.M., 1972. The Earth's age and geochronology. Pergamon Press Ltd, 178p.
ANSTO: SIMS (Secondary Ion Mass Spectrometer)http://www.ansto.gov.au/ansto/environment1/capabilities/sims/dynamic.htm
Australian National University Research School of Earth Sciences: The SHRIMP probehttp://wwwrses.anu.edu.au/gig/Probe/SHRIMP.html
Iraq’s proven oil reserves top 115 billion barrels, with the potential for another 45 billion to 100 billion barrels of recoverable oil, according to the U.S. Energy Information Administration (EIA). The country hosts nine “super giants” — fields holding more than 5 billion barrels of oil — and 22 “giant” fields, which each have more than 1 billion barrels of oil. Yet thanks in part to three wars, and the combination of international sanctions and a government that opposed foreign investments — and the technological improvements they bring — over the past couple of decades, Iraq has the lowest reserve-to-production ratio of all major oil-producing countries. In fact, Iraq hosts the largest untapped reserves in the world, says James Paul, executive director of Global Policy Forum in New York. “It’s a pity, because at $95 a barrel, or $195 a barrel as [oil] may be in the near future, there’s a lot of money to be made,” says Gal Luft, executive director of the Institute for the Analysis of Global Security in Washington, D.C. “The net loss to the Iraqi economy and the Iraqi people is sad.” By the end of 2007, Iraq was averaging about 2.0 million barrels of oil per day (bpd) production, according to EIA, well below the 2.6 million bpd production before the U.S.-led invasion in 2003.
Iraq’s oil ministry aims to increase Iraq’s oil production to 6 million bpd by the end of this decade. To do so, the ministry says Iraq will need foreign investment of $25 million to $75 million in the oil sector. However, the security situation and the legal complications are such that that investment, at least from multinational oil companies, is unlikely in the near future, Luft says.
From April 2003 to May 2007, there were 400 individual attacks on Iraq’s oil infrastructure, according to EIA. Furthermore, roadside bombings, acts of sabotage and insurgent uprisings are rampant across Iraq. And now the Turkish government is sending troops into the Kurdistan region in northern Iraq to neutralize Kurdish forces. Because of this, “investors are sitting on their money,” Luft says. “There needs to be a sense that there is no back-sliding on security,” he says. “If international oil companies see that the region is moving toward greater security, they can say ‘things are looking rosier’ and can take baby steps toward investment.” Without a formal oil policy in place, however, multinational oil companies simply will not go into Iraq, Paul says.
Iraq’s Hydrocarbon Law — which is supposed to lay out the legal conditions for investment and international participation in Iraq’s oil and gas sector, including exactly how much control the companies have relative to the Iraqi government — is what everyone is waiting for, Paul says. The companies “want a legal status that can’t be changed” with every new administration or vote, he says. The Hydrocarbon Law was first presented to Iraq’s parliament on Feb. 27, 2007. As Geotimes went to press, it was still under considerable debate and unlikely to be passed anytime soon, given that some 70 percent of Iraqis are opposed to a law that gives control to anyone other than themselves, Paul says. Considering that the “Exxons of the world know it is better to wait until legality is established in Iraq,” the country is thus at an impasse, he says. And how to break this impasse is the “$64,000, or maybe $64 billion or trillion question,” he says. “Will the U.S. eventually be able to impose its will on Iraq? I don’t think we can say where this thing will end up,” he says.
Meanwhile, the Kurdistan Regional Government in northern Iraq is setting up its own oil exploration and production agreements, disregarding the central government’s vehement opposition to the move. While the big multinational oil companies are abstaining from getting involved, smaller international oil companies from Turkey, Canada, Norway, the United Kingdom, Switzerland, South Korea, China, Vietnam, Russia and other countries are setting up agreements with the Kurdistan government, says Naji Abdul-Rahman, a former oil engineer in Iraq. Despite threats from the central government that they will be “blacklisted” from further production and legal contracts once a national oil law is in place, these companies are going ahead with seismic and structural analyses and other exploration in the north, he says.
“The results are exciting,” says Mohammad Al-Gailani, managing director of GeoDesign Limited in the United Kingdom, whose company has been involved in evaluating prospects in northern Iraq. A handful of exploration wells have already revealed fields in which production could easily reach more than 100,000 bpd, he says. “Just the little work we’ve done so far has shown that the value of the whole reserves in Iraq is exponentially higher” than international estimates — which are based largely on decades-old seismic surveys, Al-Gailani says. Thus “high-risk fields,” such as those in the north, “become even more attractive to these smaller companies,” he says. Indeed, with oil prices as high as they are, some smaller companies are willing to take risks they might not have in the past, Abdul-Rahman says. Whether the central government’s threats will scare off potential investors remains to be seen, Luft says.
To get Iraq’s oil system to where it needs to be to help the Iraqi economy will be expensive and time-consuming, Luft says. A lot needs to be done to upgrade the infrastructure, he says: “Everything is very, very old and neglected.” Furthermore, he says, there is the question of what will happen if and/or when the United States and the United Kingdom withdraw from Iraq. “In the south, where most of the oil is produced, the big question is what will happen when the Brits withdraw,” Luft says. That could create a vacuum of power, which could lead to even more sabotage, oil theft and problems.
Tuesday, April 22, 2008
In South Korea, the situation is the same especially with solar technology improving greatly and the costs of purchasing solar panels going down. Like in the country’s Gangneung city, a coastal city. You would see that quite a number of houses have gone ahead and installed solar panels on their roofs. Some of the owners of houses have also taken the liberty of putting up solar water heaters beside their solar panels.
Also, the country’s government has already been working on a new proposal - the building of a solar plant that would be able to create 20 megawatts. Experts say that if this project pushes through, it just may rise high above Spain’s own plant which is currently the largest solar farm in the entire globe.
The land surrounding the Taklimakan is equally hostile. To the northeast lies the Gobi desert, almost as harsh in climate as the Taklimakan itself; on the remaining three sides lie some of the highest mountains in the world. To the South are the Himalaya, Karakorum and Kunlun ranges, which provide an effective barrier separating Central Asia from the Indian sub-continent. Only a few icy passes cross these ranges, and they are some of the most difficult in the world; they are mostly over 5000 metres in altitude, and are dangerously narrow, with precipitous drops into deep ravines. To the north and west lie the Tianshan and Pamir ranges; though greener and less high, the passes crossing these have still provided more than enough problems for the travellers of the past. Approaching the area from the east, the least difficult entry is along the `Gansu Corridor', a relatively fertile strip running along the base of the Qilian mountains, separating the great Mongolian plateau and the Gobi from the Tibetan High Plateau. Coming from the west or south, the only way in is over the passes.
The Early History of The Region On the eastern and western sides of the continent, the civilisations of China and the West developed. The western end of the trade route appears to have developed earlier than the eastern end, principally because of the development of the the empires in the west, and the easier terrain of Persia and Syria. The Iranian empire of Persia was in control of a large area of the Middle East, extending as far as the Indian Kingdoms to the east. Trade between these two neighbours was already starting to influence the cultures of these regions.
This region was taken over by Alexander the Great of Macedon, who finally conquered the Iranian empire, and colonised the area in about 330 B.C., superimposing the culture of the Greeks. Although he only ruled the area until 325 B.C., the effect of the Greek invasion was quite considerable. The Greek language was brought to the area, and Greek mythology was introduced. The aesthetics of Greek sculpture were merged with the ideas developed from the Indian kingdoms, and a separate local school of art emerged. By the third century B.C., the area had already become a crossroads of Asia, where Persian, Indian and Greek ideas met. It is believed that the residents of the Hunza valley in the Karakorum are the direct descendents of the army of Alexander; this valley is now followed by the Karakorum Highway, on its way from Pakistan over to Kashgar, and indicates how close to the Taklimakan Alexander may have got.
This `crossroads' region, covering the area to the south of the Hindu Kush and Karakorum ranges, now Pakistan and Afghanistan, was overrun by a number of different peoples. After the Greeks, the tribes from Palmyra, in Syria, and then Parthia, to the east of the Mediterranean, took over the region. These peoples were less sophisticated than the Greeks, and adopted the Greek language and coin system in this region, introducing their own influences in the fields of sculpture and art.
Close on the heels of the Parthians came the Yuezhi people from the Northern borders of the Taklimakan. They had been driven from their traditional homeland by the Xiongnu tribe (who later became the Huns and transfered their attentions towards Europe), and settled in Northern India. Their descendents became the Kushan people, and in the first century A.D. they moved into this crossroads area, bringing their adopted Buddhist religion with them. Like the other tribes before them, they adopted much of the Greek system that existed in the region. The product of this marriage of cultures was the Gandhara culture, based in what is now the Peshawar region of northwest Pakistan. This fused Greek and Buddhist art into a unique form, many of the sculptures of Buddhist deities bearing strong resemblances to the Greek mythological figure Heracles. The Kushan people were the first to show Buddha in human form, as before this time artists had preferred symbols such as the footprint, stupa or tree of enlightenment, either out of a sense of sacrilege or simply to avoid persecution.
The eastern end of the route developed rather more slowly. In China, the Warring States period was brought to an end by the Qin state, which unified China to form the Qin Dynasty, under Qin Shi Huangdi. The harsh reforms introduced to bring the individual states together seem brutal now, but the unification of the language, and standardisation of the system, had long lasting effects. The capital was set up in Changan, which rapidly developed into a large city, now Xian.
The Xiongnu tribe had been periodically invading the northern borders during the Warring States period with increasing frequency. The northern-most states had been trying to counteract this by building defensive walls to hinder the invaders, and warn of their approach. Under the Qin Dynasty, in an attempt to subdue the Xiongnu, a campaign to join these sections of wall was initiated, and the `Great Wall' was born. When the Qin collapsed in 206 B.C., after only 15 years, the unity of China was preserved by the Western Han Dynasty, which continued to construct the Wall.
During one of their campaigns against the Xiongnu, in the reign of Emperor Wudi, the Han learnt from some of their prisoners that the Yuezhi had been driven further to the west. It was decided to try to link up with these peoples in order to form an alliance against the Xiongnu. The first intelligence operation in this direction was in 138 B.C. under the leadership of Zhang Qian, brought back much of interest to the court, with information about hitherto unknown states to the west, and about a new, larger breed of horse that could be used to equip the Han cavalry. The trip was certainly eventful, as the Xiongnu captured them, and kept them hostage for ten years; after escaping and continuing the journey, Zhang Qian eventually found the Yuezhi in Northern India. Unfortunately for the Han, they had lost any interest in forming an alliance against the Xiongnu. On the return journey, Zhang Qian and his delegation were again captured, and it was not until 125 B.C. that they arrived back in Changan. The emperor was much interested by what they found, however, and more expeditions were sent out towards the West over the following years. After a few failures, a large expedition managed to obtain some of the so-called `heavenly horses', which helped transform the Han cavalry. These horses have been immortalised in the art of the period, one of the best examples being the small bronze `flying horse' found at Wuwei in the Gansu Corridor, now used as the emblem of the China International Travel Service. Spurred on by their discoveries, the Han missions pushed further westwards, and may have got as far as Persia. They brought back many objects from these regions, in particular some of the religious artwork from the Gandharan culture, and other objects of beauty for the emperor. By this process, the route to the west was opened up. Zhang Qian is still seen by many to be the father of the Silk Road.
In the west, the Greek empire was taken over by the Roman empire. Even at this stage, before the time of Zhang Qian, small quantities of Chinese goods, including silk, were reaching the west. This is likely to have arrived with individual traders, who may have started to make the journey in search of new markets despite the danger or the political situation of the time.
The Nature of the Route The description of this route to the west as the `Silk Road' is somewhat misleading. Firstly, no single route was taken; crossing Central Asia several different branches developed, passing through different oasis settlements. The routes all started from the capital in Changan, headed up the Gansu corridor, and reached Dunhuang on the edge of the Taklimakan. The northern route then passed through Yumen Guan (Jade Gate Pass) and crossed the neck of the Gobi desert to Hami (Kumul), before following the Tianshan mountains round the northern fringes of the Taklimakan. It passed through the major oases of Turfan and Kuqa before arriving at Kashgar, at the foot of the Pamirs. The southern route branched off at Dunhuang, passing through the Yang Guan and skirting the southern edges of the desert, via Miran, Hetian (Khotan) and Shache (Yarkand), finally turning north again to meet the other route at Kashgar. Numerous other routes were also used to a lesser extent; one branched off from the southern route and headed through the Eastern end of the Taklimakan to the city of Loulan, before joining the Northern route at Korla. Kashgar became the new crossroads of Asia; from here the routes again divided, heading across the Pamirs to Samarkand and to the south of the Caspian Sea, or to the South, over the Karakorum into India; a further route split from the northern route after Kuqa and headed across the Tianshan range to eventually reach the shores of the Caspian Sea, via Tashkent.
Secondly, the Silk Road was not a trade route that existed solely for the purpose of trading in silk; many other commodities were also traded, from gold and ivory to exotic animals and plants. Of all the precious goods crossing this area, silk was perhaps the most remarkable for the people of the West. It is often thought that the Romans had first encountered silk in one of their campaigns against the Parthians in 53 B.C, and realised that it could not have been produced by this relatively unsophisticated people. They reputedly learnt from Parthian prisoners that it came from a mysterious tribe in the east, who they came to refer to as the silk people, `Seres'. In practice, it is likely that silk and other goods were beginning to filter into Europe before this time, though only in very small quantities. The Romans obtained samples of this new material, and it quickly became very popular in Rome, for its soft texture and attractiveness. The Parthians quickly realised that there was money to be made from trading the material, and sent trade missions towards the east. The Romans also sent their own agents out to explore the route, and to try to obtain silk at a lower price than that set by the Parthians. For this reason, the trade route to the East was seen by the Romans as a route for silk rather than the other goods that were traded. The name `Silk Road' itself does not originate from the Romans, however, but is a nineteenth century term, coined by the German scholar, von Richthofen.
In addition to silk, the route carried many other precious commodities. Caravans heading towards China carried gold and other precious metals, ivory, precious stones, and glass, which was not manufactured in China until the fifth century. In the opposite direction furs, ceramics, jade, bronze objects, lacquer and iron were carried. Many of these goods were bartered for others along the way, and objects often changed hands several times. There are no records of Roman traders being seen in Changan, nor Chinese merchants in Rome, though their goods were appreciated in both places. This would obviously have been in the interests of the Parthians and other middlemen, who took as large a profit from the change of hands as they could.
The Development of the Route The development of these Central Asian trade routes caused some problems for the Han rulers in China. Bandits soon learnt of the precious goods travelling up the Gansu Corridor and skirting the Taklimakan, and took advantage of the terrain to plunder these caravans. Caravans of goods needed their own defence forces, and this was an added cost for the merchants making the trip. The route took the caravans to the farthest extent of the Han Empire, and policing this route became a big problem. This was partially overcome by building forts and defensive walls along part of the route. Sections of `Great Wall' were built along the northern side of the Gansu Corridor, to try to prevent the Xiongnu from harming the trade; Tibetan bandits from the Qilian mountains to the south were also a problem. Sections of Han dynasty wall can still be seen as far as Yumen Guan, well beyond the recognised beginning of the Great Wall at Jiayuguan. However, these fortifications were not all as effective as intended, as the Chinese lost control of sections of the route at regular intervals.
The Han dynasty set up the local government at Wulei, not far from Kuqa on the northern border of the Taklimakan, in order to `protect' the states in this area, which numbered about 50 at the time. At about the same period the city of Gaochang was constructed in the Turfan basin. This developed into the centre of the Huihe kingdom; these peoples later became the Uygur minority who now make up a large proportion of the local population. Many settlements were set up along the way, mostly in the oasis areas, and profited from the passing trade. They also absorbed a lot of the local culture, and the cultures that passed them by along the route. Very few merchants traversed the full length of the road; most simply covered part of the journey, selling their wares a little further from home, and then returning with the proceeds. Goods therefore tended to moved slowly across Asia, changing hands many times. Local people no doubt acted as guides for the caravans over the most dangerous sections of the journey.
After the Western Han dynasty, successive dynasties brought more states under Chinese control. Settlements came and went, as they changed hands or lost importance due to a change in the routes. The chinese garrison town of Loulan, for example, on the edge of the Lop Nor lake, was important in the third century A.D., but was abandoned when the Chinese lost control of the route for a period. Many settlements were buried during times of abandonment by the sands of the Taklimakan, and could not be repopulated.
The settlements reflected the nature of the trade passing through the region. Silk, on its way to the west, often got no further than this region of Central Asia. The Astana tombs, where the nobles of Gaochang were buried, have turned up examples of silk cloth from China, as well as objects from as far afield as Persia and India. Much can be learned about the customs of the time from the objects found in these graves, and from the art work of the time, which has been excellently preserved on the tomb walls, due to the extremely dry conditions. The bodies themselves have also been well preserved, and may allow scientific studies to ascertain their origins.
The most significant commodity carried along this route was not silk, but religion. Buddhism came to China from India this way, along the northern branch of the route. The first influences came as the passes over the Karakorum were first explored. The Eastern Han emperor Mingdi is thought to have sent a representative to India to discover more about this strange faith, and further missions returned bearing scriptures, and bringing with them India priests. With this came influences from the Indian sub-continent, including Buddhist art work, examples of which have been found in several early second century tombs in present-day Sichuan province. This was considerably influenced by the Himalayan Massif, an effective barrier between China and India, and hence the Buddhism in China is effectively derived from the Gandhara culture by the bend in the Indus river, rather than directly from India. Buddhism reached the pastures of Tibet at a rather later period, not developing fully until the seventh century. Along the way it developed under many different influences, before reaching central China. This is displayed very cleared in the artwork, where many of the cave paintings show people with clearly different ethnic backgrounds, rather than the expected Cental and East Asian peoples.
The greatest flux of Buddhism into China occurred during the Northern Wei dynasty, in the fourth and fifth centuries A.D. This was at a time when China was divided into several different kingdoms, and the Northern Wei dynasty had its capital in Datong in present day Shanxi province. The rulers encouraged the development of Buddhism, and more missions were sent towards India. The new religion spread slowly eastwards, through the oases surrounding the Taklimakan, encouraged by an increasing number of merchants, missionaries and pilgrims. Many of the local peoples, the Huihe included, adopted Buddhism as their own religion. Faxian, a pilgrim from China, records the religious life in the Kingdoms of Khotan and Kashgar in 399 A.D. in great detail. He describes the large number of monasteries that had been built, and a large Buddhist festival that was held while he was there.
Some devotees were sufficiently inspired by the new ideas that they headed off in search of the source, towards Gandhara and India; others started to build monasteries, grottos and stupas. The development of the grotto is particularly interesting; the edges of the Taklimakan hide some of the best examples in the world. The hills surrounding the desert are mostly of sandstone, with any streams or rivers carving cliffs that can be relatively easily dug into; there was also no shortage of funds for the work, particularly from wealthy merchants, anxious to invoke protection or give thanks for a safe desert crossing. Gifts and donations of this kind were seen as an act of merit, which might enable the donor to escape rebirth into this world. In many of the murals, the donors themselves are depicted, often in pious attitude. This explains why the Mogao grottos contain some of the best examples of Buddhist artwork; Dunhuang is the starting point for the most difficult section of the Taklimakan crossing.
The grottos were mostly started at about the same period, and coincided with the beginning of the Northern Wei Dynasty. There are a large cluster in the Kuqa region, the best examples being the Kyzil grottos; similarly there are clusters close to Gaochang, the largest being the Bezeklik grottos. Probably the best known ones are the Mogao grottos at Dunhuang, at the eastern end of the Taklimakan. It is here that the greatest number, and some of the best examples, are to be found. More is known about the origins of these, too, as large quantities of ancient documents have been found. These are on a wide range of subjects, and include a large number of Buddhist scriptures in Chinese, Sanskrit, Tibetan, Uygur and other languages, some still unknown. There are documents from the other faiths that developed in the area, and also some official documents and letters that reveal a lot about the system of government at the time.
The grotto building was not confined to the Taklimakan; there is a large cluster at Bamiyan in the Hindu Kush, in present-day Afghanistan. It is here that the second largest sculpture of Buddha in the world can be found, at 55 metres high.
For the archaeologist these grottos are particularly valuable sources of information about the Silk Road. Along with the images of Buddhas and Boddhisatvas, there are scenes of the everyday life of the people at the time. Scenes of celebration and dancing give an insight into local customs and costume. The influences of the Silk Road traffic are therefore quite clear in the mix of cultures that appears on these murals at different dates. In particular, the development of Buddhism from the Indian/Gandharan style to a more individual faith is evident on studying the murals from different eras in any of the grotto clusters. Those from the Gandharan school have more classical features, with wavy hair and a sharper brow; they tend to be dressed in toga-like robes rather than a loin cloth. Those of the Northern Wei have a more Indian appearance, with narrower faces, stretched ear-lobes, and a more serene aura. By the Tang dynasty, when Buddhism was well developed in China, many of the statues and murals show much plumper, more rounded and amiable looking figures. By the Tang dynasty, the Apsara (flying deity, similar to an angel in Christianity) was a popular subject for the artists.
It is also interesting to trace the changes in styles along the length of the route, from Kuqa in the west, via the Turfan area and Dunhuang, to the Maijishan grottos about 350 kilometres from Xian, and then as far into China as Datong. The Northern Wei dynasty, that is perhaps the most responsible for the spread of Buddhism in China, started the construction of the Yungang grottos in northern Shanxi province. When the capital of the Northern Wei was transfered to Luoyang, the artists and masons started again from scratch, building the Longmen grottos. These two more `Chinese' grottos emphasised carving and statuary rather than the delicate murals of the Taklimakan regions, and the figures are quite impressive in their size; the largest figure at Yungang measures more than 17 metres in height, second only in China to the great Leshan Buddha in Sichuan, which was constructed in the early 8th Century. The figures are mostly depicted in the `reassurance' pose, with right hand raised, as an apology to the adherents of the Buddhist faith for the period of persecution that had occurred during the early Northern Wei Dynasty before construction was started.
The Buddhist faith gave birth to a number of different sects in Central Asia. Of these, the `Pure Land' and `Chan' (Zen) sects were particularly strong, and were even taken beyond China; they are both still flourishing in Japan.
Christianity also made an early appearance on the scene. The Nestorian sect was outlawed in Europe by the Roman church in 432 A.D., and its followers were driven eastwards. From their foothold in Northern Iran, merchants brought the faith along the Silk Road, and the first Nestorian church was consecrated at Changan in 638 A.D. This sect took root on the Silk Road, and survived many later attempts to wipe them out, lasting into the fourteenth century. Many Nestorian writings have been found with other documents at Dunhuang and Turfan. Manichaeism, a third century Persian religion, also influenced the area, and had become quite well developed by the beginning of the Tang Dynasty.
The Greatest Years The height of the importance of the Silk Road was during the Tang dynasty, with relative internal stability in China after the divisions of the earlier dynasties since the Han. The individual states has mostly been assimilated, and the threats from marauding peoples was rather less.
During this period, in the seventh century, the Chinese traveller Xuan Zhuang crossed the region on his way to obtain Buddhist scriptures from India. He followed the northern branch round the Taklimakan on his outward journey, and the southern route on his return; he carefully recorded the cultures and styles of Buddhism along the way. On his return to the Tang capital at Changan, he was permitted to build the `Great Goose Pagoda' in the southern half of the city, to house the more than 600 scriptures that he had brought back from India. He is still seen by the Chinese as an important influence in the development of Buddhism in China, and his travels were dramatised by in the popular classic `Tales of a Journey to the West'.
The art and civilisation of the Silk Road achieved its highest point in the Tang Dynasty. Changan, as the starting point of the route, as well as the capital of the dynasty, developed into one of the largest and most cosmopolitan cities of the time. By 742 A.D., the population had reached almost two million, and the city itself covered almost the same area as present-day Xian, considerably more than within the present walls of the city. The 754 A.D. census showed that five thousand foreigners lived in the city; Turks, Iranians, Indians and others from along the Road, as well as Japanese, Koreans and Malays from the east. Many were missionaries, merchants or pilgrims, but every other occupation was also represented. Rare plants, medicines, spices and other goods from the west were to be found in the bazaars of the city. It is quite clear, however, despite the exotic imports, that the Chinese regarded all foreigners as barbarians; the gifts provided for the Emperors by foreign rulers were simply considered as tribute from vassal states.
After the Tang, however, the traffic along the road subsided, along with the grotto building and art of the period. The Five Dynasties period did not maintain the internal stability of the Tang dynasty, and again neighbouring states started to plunder the caravans. China was partially unified again in the Song dynasty, but the Silk Road was not as important as it had been in the Tang.
From the point of view of those in the far west, China was still an unknown territory, and silk production was not understood. Since the days of Alexander the Great, there had been some knowledge of India, but there was no real knowledge of, or contact with, the `Seres' until about the 7th century, when information started to filter along the Road. It was at this time that the rise of Islam started to affect Asia, and a curtain came down between the east and west. Trade relations soon resumed, however, with the Moslems playing the part of middlemen. The sea route to China was explored at this time, and the `Sea Silk Route' was opened, eventually holding a more important place than the land route itself, as the land route became less profitable.
But the final shake-up that occurred was to come from a different direction; the hoards from the grasslands of Mongolia.
The Mongols Trade along the route was adversely affected by the strife which built up between the Christian and Moslem worlds. The Crusades brought the Christian world a little nearer to Central Asia, but the unified Moslem armies under Saladin drove them back again. In the Fourth Crusade, the forces of Latin Christianity scored a triumph over their Greek rivals, with the capture of Constantinople (Istanbul). However, it was not the Christians who finally split the Moslem world, but the Mongols from the east. Whilst Europe and Western Asia were torn by religious differences, the Mongols had only the vaguest of religious beliefs. Several of the tribes of Turkestan which had launched offensives westwards towards Persia and Arabia, came to adopt Islam, and Islam had spread far across Central Asia, but had not reached as far as the tribes which wandered the vast grasslands of Mongolia. These nomadic peoples had perfected the arts of archery and horsemanship. With an eye to expanding their sphere of influence, they met in 1206 and elected a leader for their unified forces; he took the title Great Khan. Under the leadership of Genghis Khan, they rapidly proceeded to conquer a huge region of Asia. The former Han city of Jiaohe, to the west of Turfan, was decimated by the Mongols as they passed through on their way westwards. The Empire they carved out enveloped the whole of Central Asia from China to Persia, and stretched as far west as the Mediterranean. This Mongol empire was maintained after Genghis' death, with the western section of the empire divided into three main lordships, falling to various of his descendents as lesser Khans, and with the eastern part remaining under the rule of the Great Khan, a title which was inherited from by Kublai Khan. Kubilai completed the conquest of China, subduing the Song in the South of the country, and established the Yuan dynasty.
The partial unification of so many states under the Mongol Empire allowed a significant interaction between cultures of different regions. The route of the Silk Road became important as a path for communication between different parts of the Empire, and trading was continued. Although less `civilised' than people in the west, the Mongols were more open to ideas. Kubilai Khan, in particular, is reported to have been quite sympathetic to most religions, and a large number of people of different nationalities and creeds took part in the trade across Asia, and settled in China. The most popular religion in China at the time was Daoism, which at first the Mongols favoured. However, from the middle of the thirteenth century onwards, buddhist influence increased, and the early lamaist Buddhism from Tibet was particularly favoured. The two religions existed side by side for a long period during the Yuan dynasty. This religious liberalism was extended to all; Christianity first made headway in China in this period, with the first Roman Catholic arch-bishopric set up in Beijing in 1307. The Nestorian church was quite widespread in China; Jews and Moslems also populated several of the major cities, though they do not seem to have made many converts.
It was at this time that Europeans first ventured towards the lands of the `Seres'. The earliest were probably Fransiscan friars who are reported to have visited the Mongolian city of Karakorum. The first Europeans to arrive at Kubilai's court were Northern European traders, who arrived in 1261. However, the most well known and best documented visitor was the Italian Marco Polo. As a member of a merchant family from Venice, he was a good businessman and a keen observer. Starting in 1271, at the age of only seventeen, his travels with his father and uncle took him across Persia, and then along the southern branch of the Silk Road, via Khotan, finally ending at the court of Kubilai Khan at Khanbalik, the site of present-day Beijing, and the summer palace, better known as Xanadu. He travelled quite extensively in China, before returning to Italy by ship, via Sumatra and India to Hormuz and Constantinople.
He describes the way of life in the cities and small kingdoms through which his party passed, with particular interest on the trade and marriage customs. His classification of other races centre mainly on their religion, and he looks at things with the eyes of one brought up under the auspices of the Catholic Church; it is therefore not surprising that he has a great mistrust of the Moslems, but he seems to have viewed the `Idolaters' (Buddhists and Hindus) with more tolerance. He judges towns and countryside in terms of productivity; he appears to be have been quick to observe available sources of food and water along the way, and to size up the products and manufacture techniques of the places they passed through. His description of exotic plants and beasts are sufficiently accurate to be quite easily recognizable, and better than most of the textbooks of the period. He seems to have shown little interest in the history of the regions he was passing through, however, and his reports of military campaigns are full of inaccuracies, though this might be due to other additions or misinformation.
The `Travels' were not actually written by Marco Polo himself. After his return to the West in 1295, he was captured as a prisoner of war in Genoa, when serving in the Venetian forces. Whilst detained in prison for a year, he met Rustichello of Pisa, a relatively well-known romance writer and a fellow prisoner of war. Rustichello was obviously attracted to the possibilities of writing a romantic tale of adventure about Polo's travels; it should be remembered that the book was written for entertainment rather than as a historic document. However, the collaboration between them, assuming that the story has not been embroidered excessively by Rustichello, gives an interesting picture of life along the Silk Road in the time of the Khans. Some of the tales are no doubt due to the romance-writing instincts of Rustichello, and some of those due to Polo are at best third-hand reports from people he met; however, much of the material can be verified against Chinese and Persian records. As a whole, the book captured public notice at the time, and added much to what was known of Asian geography, customs and natural history.
The Decline of the Route However, the Mongolian Empire was to be fairly short-lived. Splits between the different khans had erupted as early as 1262. Although the East was considerably more stable, especially under the rule of Kubilai, it also succumbed to a resurgence of Chinese nationalism, and after several minor local rebellions in the first few decades of the fourteenth century, principally in the south of China, the Yuan dynasty was finally replaced by the Ming dynasty in 1368. With the disintegration of the Mongol empire, the revival of Islam and the isolationist policies of the Ming dynasty, the barriers rose again on the land route between East and West.
Despite the presence of the Mongols, trade along the Silk Road never reached the heights that it did in the Tang dynasty. The steady advance of Islam, temporarily halted by the Mongols, continued until it formed a major force across Central Asia, surrounding the Taklimakan like Buddhism had almost a millennium earlier. The artwork of the region suffered under the encroach of Islam. Whereas the Buddhist artists had concentrated on figures in painting and sculpture, the human form was scorned in Islamic artwork; this difference led to the destruction of much of the original artwork. Many of the grottos have been defaced in this way, particularly at the more accessible sites such as Bezeklik, near Turfan, where most of the human faces in the remaining frescoes have been scratched out.
The demise of the Silk Road also owes much to the development of the silk route by sea. It was becoming rather easier and safer to transport goods by water rather than overland. Ships had become stronger and more reliable , and the route passed promising new markets in Southern Asia. The overland problems of `tribal politics' between the different peoples along the route, and the presence of middlemen, all taking their cut on the goods, prompted this move. The sea route, however, suffered from the additional problems of bad weather and pirates. In the early fifteenth century, the Chinese seafarer Zhang He commanded seven major maritime expeditions to Southeast Asia and India, and as far as Arabia and the east coast of Africa. Diplomatic relations were built up with several countries along the route, and this increase the volume of trade Chinese merchants brought to the area. In the end, the choice of route depended very much upon the political climate of the time.
The encroach of the deserts into the inhabited land made life on the edges of the Taklimakan and Gobi Deserts particularly difficult. Any settlement abandoned for a while was swallowed by the desert, and so resettlement became increasingly difficult. These conditions were only suitable in times of peace, when effort could be spent countering this advance, and maintaining water sources.
The attitude of the later Chinese dynasties was the final blow to the trade route. The isolationist policies of the Ming dynasties did nothing to encourage trade between China and the rapidly developing West. This attitude was maintained throughout the Ming and Qing dynasties, and only started to change after the Western powers began making inroads into China in the nineteenth century. By the beginning of the Eighteenth Century, the Qing dynasty subdued the Dzungar people, however, and annexed the whole Taklimakan region, forming the basis of present-day Xinjiang province. This restored China to the state it had been in in the Han dynasty, with full control of the western regions, but also including the territories and Tibet and Mongolia.
However, as trade with the West subsided, so did the traffic along the Road, and all but the best watered oases survived. The grottos and other religious sites were long since neglected, now that the local peoples had espoused a new religion, and the old towns and sites were buried deeper beneath the sands.
Foreign Influence Renewed interest in the Silk Road only emerged among western scholars towards the end of the nineteenth century. This emerged after various countries started to explore the region. The foreign involvement in this area was due mostly to the interest of the powers of the time in expanding their territories. The British, in particular, were interested in consolidating some of the land north of their Indian territories. The first official trip for the Survey of India was in 1863, and soon afterwards, the existence of ancient cities lost in the desert was confirmed. A trade delegation was sent to Kashgar in 1890, and the British were eventually to set up a consulate in 1908. They saw the presence of Russia as a threat to the trade developing between Kashgar and India, and the power struggle between these two empires in this region came to be referred to as the `Great Game'. British agents (mostly Indians) crossed the Himalayas from Ladakh and India to Kashgar, travelling as merchants, and gathering what information they could, including surveying the geography of the route. At a similar time, Russians were entering from the north; most were botanists, geologists or cartographers, but they had no doubt been briefed to gather whatever intelligence they could. The Russians were the first to chance on the ruined cities at Turfan. The local treasure hunters were quick to make the best of these travellers, both in this region and near Kashgar, and noting the interest the foreigners showed towards the relics, sold them a few of the articles that they had dug out of the ruins. In this way a few ancient articles and old manuscripts started to appear in the West. When these reached the hands of Orientalists in Europe, and the manuscripts were slowly deciphered, they caused a large deal of interest, and more people were sent out to look out for them.
The study of the Road really took off after the expeditions of the Swede Sven Hedin in 1895. He was an accomplished cartographer and linguist, and became one of the most renowned explorers of the time. He crossed the Pamirs to Kashgar, and then set out to explore the more desolate parts of the region. He even succeeded in making a crossing of the centre of the Taklimakan, though he was one of only three members of the party who made it across, the rest succumbing to thirst after their water had run out. He was intrigued by local legends of demons in the Taklimakan, guarding ancient cities full of treasure, and met several natives who had chanced upon such places. In his later travels, he discover several ruined cities on the south side of the desert, and his biggest find, the city of Loulan, from which he removed a large number of ancient manuscripts.
After Hedin, the archaeological race started. Sir Aurel Stein of Britain and Albert von Le Coq of Germany were the principle players, though the Russians and French, and then the Japanese, quickly followed suit. There followed a period of frenzied digging around the edges of the Taklimakan, to discover as much as possible about the old Buddhist culture that had existed long before. The dryness of the climate, coupled with the exceedingly hot summers and cold winters, made this particularly difficult. However the enthusiasm to discover more of the treasures of the region, as well as the competition between the individuals and nations involved, drove them to continue. Although they produced reports of what they discovered, their excavation techniques were often far from scientific, and they removed whatever they could from the sites in large packing cases for transport to the museums at home. The manuscripts were probably the most highly prized of the finds; tales of local people throwing these old scrolls into rivers as rubbish tormented them. Removal of these from China probably did help preserve them. However, the frescoes from the grottos also attracted their attention, and many of the best ones were cut into sections, and carefully peeled off the wall with a layer of plaster; these were then packaged very carefully for transport. To their credit, almost all these murals survived the journey, albeit in pieces.
The crowning discovery was of a walled-up library within the Mogao grottos at Dunhuang. This contained a stack of thousands of manuscripts, Buddhist paintings and silk temple banners. The manuscripts were in Chinese, Sanskrit, Tibetan, Uyghur and several other less widely known languages, and they covered a wide range of subjects; everything from sections of the Lutras Sutra to stories and ballads from the Tang dynasty and before. Among these is what is believed to be the world's oldest printed book. This hoard had been discovered by a Daoist monk at the beginning of the twentieth century, and he had appointed himself as their protector. The Chinese authorities appear to have been aware of the existence of the library, but were perhaps not fully aware of its significance, and they had decided to leave the contents where they were, under the protection of the monk. On hearing of this hoard, Stein came to see them; he gradually persuaded the monk to part with a few of the best for a small donation towards the rebuilding of the temple there. On successive visits, he removed larger quantities; the French archaeologist Pelliot also got wind of this discovery, and managed to obtain some. The frescoes at Dunhuang were also some of the best on the whole route, and many of the most beautiful ones were removed by the American professor Langdon Warner and his party.
The archaeological free-for-all came to a close after a change in the political scene. On 25th May 1925 a student demonstration in the treaty port of Shanghai was broken up by the British by opening fire on them, killing a number of the rioters. This instantly created a wave of anti-foreign hostility throughout China, and effectively brought the explorations of the Western Archaeologists to an end. The Chinese authorities started to take a much harsher view of the foreign intervention, and made the organisation of the trips much more difficult; they started to insist that all finds should be turned over to the relevant Chinese organs. This effectively brought an end to foreign exploration of the region.
The treasures of the ancient Silk Road are now scattered around museums in perhaps as many as a dozen countries. The biggest collections are in the British Museum and in Delhi, due to Stein and in Berlin, due to von Le Coq. The manuscripts attracted a lot of scholarly interest, and deciphering them is still not quite complete. Most of them are now in the British Library, and available for specialist study, but not on display. A large proportion of the Berlin treasures were lost during the Second World War; twenty eight of the largest frescoes, which had been attached to the walls of the old Ethnological Museum in Berlin for the purposes of display to the public, were lost in an Allied Air Force bombing raids between 1943 and 1945. A huge quantity of material brought back to London by Stein has mostly remained where it was put; museums can never afford the space to show more than just a few of the better relics, especially not one with such a large worldwide historical coverage as the British Museum.
The Chinese have understandably taken a harsh view of the `treasure seeking' of these early Western archaeologists. Much play is made on the removal of such a large quantity of artwork from the country when it was in no state to formally complain, and when the western regions, in particular, were under the control of a succession of warlord leaders. There is a feeling that the West was taking advantage of the relatively undeveloped China, and that many of the treasures would have been much better preserved in China itself. This is not entirely true; many of the grottos were crumbling after more than a thousand years of earthquakes, and substantial destruction was wrought by farmers improving the irrigation systems. Between the visits of Stein and Warner to Dunhuang, a group of White Russian soldiers fleeing into China had passed by, and defaced many of the best remaining frescoes to such an extent that the irate Warner decided to `salvage' as much as he could of the rest. The Chinese authorities at the time seem to have known about the art treasures of places like Dunhuang, but don't seem to have been prepared to protect them; the serious work of protection and restoration was left until the formation of the People's Republic.
Their only consolation is that many of the scrolls which had been purchased from native treasure-hunters at the western end of the Taklimakan at the beginning of the century were later found to have been remarkably good forgeries. Many were produced by an enterprising Moslem in Khotan, who had sensed how much money would be involved in this trade. This severely embarrassed a number of Western Orientalists, but the number of people misled attests to their quality.
The Present Day The Silk Road, after a long period of hibernation, has been increasing in importance again recently.
The fight of man against the desert, one of the biggest problems for the early travellers, is finally gaining ground. There has been some progress in controlling the progress of the shifting sands, which had previously meant having to resite settlements. The construction of roads around the edges of the Taklimakan has eased access, and the discovery of large oil reserves under the desert has encouraged this development. The area is rapidly being industrialised, and Urumchi, the present capital of Xinjiang, has become a particularly unprepossessing Han Chinese industrial city.
The trade route itself is also being reopened. The sluggish trade between the peoples of Xinjiang and those of the Soviet Union has developed quickly; trade with the C.I.S. is picking up rapidly with a flourishing trade in consumer items as well as heavy industry. The new Central Asian republics had previously contributed much of the heavy industry of the former Soviet Union, with a reliance for consumer goods on Russia. Trade with China is therefore starting to fulfill this demand. This trading has been encouraged by the recent trend towards a `socialist market economy' in China, and the increasing freedom of movement being allowed, particularly for the minorities such as those in Xinjiang. Many of these nationalities are now participating in cross-border trade, regularly making the journey to Kazakhstan and Uzbekistan.
The railway connecting Lanzhou to Urumchi has been extended to the border with Kazakhstan, where on 12th September 1990 it was finally joined to the former Soviet railway system, providing an important route to the new republics and beyond. This Eurasian Continental Bridge, built to rival the Trans-Siberian Railway, has been constructed from LianYunGang city in Jiangsu province (on the East China coast) to Rotterdam; the first phase of this development has already been completed, and the official opening of the railway was held on 1st December 1992. It is already promised to be at least 20% cheaper than the route by sea, and at 11,000 kilometres is significantly shorter. From China the route passes through Kazakhstan, Russia, Byelorussia and Poland, before reaching Germany and the Netherlands. The double-tracking of the railway from Lanzhou to the border of the C.I.S. has now been put high on the Chinese development priority list.
Restoration and Tourism Since the intervention of the West last century, interest has been growing in this ancient trade route. The books written by Stein, Hedin and others have brought the perceived oriental mystery of the route into western common knowledge. Instilled with such romantic ideals as following in the footsteps of Marco Polo, a rapidly increasing number of people have been interested in visiting these desolate places. Since China opened its doors to foreign tourists at the end of the 1970s, it has realised how much foreign currency can be brought to the country by tapping this tourist potential. This has encouraged the authorities to do their best to protect the remaining sites; restoration of many of the sites is presently underway. The Mogao grottos were probably the first place to attract this attention; the Dunhuang Research Institute has been studying and preserving the remains of the grottos, as well as what was left of the library. Restoration is presently underway; the outside of the grottos was faced in a special concrete to prevent further subsidence, and some of the murals are being touched up by a team of specially trained artists and craftsmen.
Archaeological excavations have been started by the Chinese where the foreigners laid off; significant finds have been produced from such sites as the Astana tombs, where the dead from the city of Gaochang were buried. Finds of murals and clothing amongst the grave goods have increased knowledge of life along the old Silk Road; the dryness of the climate has helped preserve the bodies of the dead, as well as their garments.
There is still a lot to see around the Taklimakan, mostly in the form of damaged grottos and ruined cities. Whilst some people are drawn by the archaeology, others are attracted by the minority peoples; there are thirteen different races of people in the region, apart from the Han Chinese, from the Tibetans and Mongolians in the east of the region, to the Tajik, Kazakhs and Uzbeks in the west. Others are drawn to the mysterious cities such as Kashgar, where the Sunday market maintains much of the old Silk Road spirit, with people of many different nationalities selling everything from spice and wool to livestock and silver knives. Many of the present-day travellers are Japanese, visiting the places where their Buddhist religion passed on its way to Japan.
Although Xinjiang is opening up, it is still not an easy place to travel around. Apart from the harsh climate and geography, many of the places are not fully open yet, and, perhaps understandably, the authorities are not keen on allowing foreigners to wander wherever they like, as Hedin and his successors had done. The desolation of the place makes it ideal for such aspects of modern life as rocket launching and nuclear bomb testing. Nevertheless, many sites can be reached without too much trouble, and there is still much to see.
Conclusions From its birth before Christ, through the heights of the Tang dynasty, until its slow demise six to seven hundred years ago, the Silk Road has had a unique role in foreign trade and political relations, stretching far beyond the bounds of Asia itself. It has left its mark on the development of civilisations on both sides of the continent. However, the route has merely fallen into disuse; its story is far from over. With the latest developments, and the changes in political and economic systems, the edges of the Taklimakan may yet see international trade once again, on a scale considerably greater than that of old, the iron horse replacing the camels and horses of the past.
BOOKS Peter Hopkirk, `Foreign Devils on the Silk Road', Oxford U.P., 1980.
`China: A Guidebook to Xinjiang', Xinjiang Educational Press, Urumqi 1988.
Marco Polo, `The Travels', translated by R. Latham, Penguin, 1958.
Jin Bohong, `In the footsteps of Marco Polo', New World Press, Beijing 1989.
Xinjiang Educational Press, `China: A Guidebook to Xinjiang', Urumqi 1988.
Shaanxi Travel and Tourism Press, `The 40 Scenic Spots along the Silk Road', Xian (1990****?)
Zhang Yehan (Ed.), `Si Lu You (Silk Road Tour)', Xinjiang People's Publishing House, Urumchi, Vol.1 (1988), Vol.2 (1990).
Brian Hook (Ed.) `The Cambridge Encyclopedia of China', Cambridge U.P., (1991,2nd
By Pratanu Banerjee
Monday, April 21, 2008
A cold desert is a desert that has snow in the winter instead of just dropping a few degrees in temperature like they would in a Hot and Dry Desert. It never gets warm enough for plants to grow. Just maybe a few grasses and mosses. The animals in Cold Deserts also have to burrow but in this case to keep warm, not cool. That is why you might find some of the same animals here as you would in the Hot and Dry Deserts.
Deserts cover about one fifth of the Earth's land surface. Most Hot and Dry Deserts are near the Tropic of Cancer or the Tropic of Capricorn. Cold Deserts are near the Arctic part of the world.
Hot and Dry Deserts temperature ranges from 20 to 25° C. The extreme maximum temperature for Hot Desert ranges from 43.5 to 49° C. Cold Deserts temperature in winter ranges from -2 to 4° C and in the summer 21 to 26° C a year
The precipitation in Hot and Dry Deserts and the precipitation in Cold Deserts is different. Hot and Dry Deserts usually have very little rainfall and/or concentrated rainfall in short periods between long rainless periods. This averages out to under 15 cm a year. Cold Deserts usually have lots of snow. They also have rain around spring. This averages out to 15 - 26 cm a year.
Hot and Dry Deserts are warm throughout the fall and spring seasons and very hot during the summer. the winters usually have very little if any rainfall. Cold Deserts have quite a bit of snow during winter. The summer and the beginning of the spring are barely warm enough for a few lichens, grasses and mosses to grow.
Hot and Dry Deserts vegetation is very rare. Plants are almost all ground-hugging shrubs and short woody trees. All of the leaves are replete (packed with nutrients). Some examples of these kinds of plant are Turpentine Bush, Prickly Pears, and Brittle Bush. For all of these plants to survive they have to have adaptations. Some of the adaptations in this case are the ability to store water for long periods of time and the ability to stand the hot weather.
Cold Desert's plants are scattered. In areas with little shade,about 10 percent of the ground is covered with plants. In some areas of sagebrush it reaches 85 percent. The height of scrub varies from 15 cm to 122 cm. All plants are either deciduous and more or less contain spiny leaves.
Hot and Dry Deserts animals include small nocturnal (only active at night) carnivores. There are also insects, arachnids, reptiles, and birds. Some examples of these animals are Borrowers, Mourning Wheatears, and Horned Vipers. Cold Deserts have animals like Antelope, Ground Squirrels, Jack Rabbits, and Kangaroo Rats.
Sunday, April 20, 2008
Fossil fuels, coal, oil and natural gas, are a non-renewable source of energy. Formed from plants and animals that lived up to 300 million years ago, fossil fuels are found in deposits beneath the earth. The fuels are burned to release the chemical energy that is stored within this resource. Energy is essential to moden society as we know it. Over 85% of our energy demands are met by the combustion of fossil fuels. These two pie charts show exactly how vital fossil fuels are to our society by showing how much of each energy resource is consumed.
Going back to the earlier days of Earth, the plants and animals that lived then eventually died and decomposed. The majority of these life forms were phytoplankton and zooplankton. When these ancient ocean dwellers died, they accumulated on the bottom of a seabed; this is how a good portion of our fossil fuel reserves began. The actual transformation process of these prehistoric creatures is not known, but scientists do know that the pressure, heat, and a great deal of time go into the making of fossil fuels.
Geologists are fairly certain that the beds of organic remains mixed with silt and mud to form layers. Over time, mineral sedimentation formed on top of the organisms, effectively entombing them in rock. As this occurred, pressure and temperature increased. These conditions, and possibly other unknown factors, caused organic material to break down into the simpler form of hydrocarbons: chains of carbon and hydrogen ranging from simple configuration to complex compounds. Another affect of extreme pressure is that the oil and gas which are various mixtures of hydrocarbons, migrate upwards to the surface. Exactly when in the conversion process and the nature of this migration is not known and is subject to conjecture.
Oil and gas are found in the ground, not freely drifting up through the earth. This is because the hydrocarbons come across rock formations that they are unable to penetrate. Complex rock structures that effectively trap gas and oil are formed by tectonic plate activity, the same forces that shift continents. The most common formation that accomplishes this is called an anticline, a dome or arched layer of rock that is impermeable by oil and gas. Underneath this barrier, a reservoir builds up. An oil reservoir is not some vast underground lake, but rather a seemingly solid layer of rock that is porous. Oil fields have been found everywhere on the planet except for the continent of Antarctica.
These fields always contain some gas, but this natural gas, methane, does not take nearly as long to form. Natural gas is also found in independent deposits within the ground as well as from others sources too. Methane is a common gas found in swamps and is also the byproduct of animals' digestive system. Incidentally, Methane is also a greenhouse gas.
Coal is formed in a similar to the other fossil fuels, though it goes through a different process, coalification. Coal is made of decomposed plant matter in conditions of high temperature and pressure, though it takes a relatively shorter amount of time to form. Coal is not a uniform substance either, it's composition varies from deposit to deposit. Factors that cause this deviation are the types of original plant matter, and the extent the plant matter decomposed. There are over 1200 distinguishable types of coal. Coal begins as peat, a mass of dead and decomposing plant matter. Peat itself has been used as fuel in the past, as an alternative to wood. Next, the peat becomes lignite, a brownish rock that contains recognizable plant matter and has a relatively low heating value. Lignite is the halfway point from peat to coal. The next phase is subbituminous. A shade of dull black, showing very little plant matter, this type of coal has a less than ideal heating value. Bituminous coal is jet black, very dense, and brittle. This type of coal has high heating value.
The main point of this is that all of these fossil fuels are made of hydrocarbons. It may come as a surprise that these two elements, hydrogen and carbon, can create many, many different compounds with unique characteristics. What makes hydrocarbons valuable to our society is the stored energy stored within them. This energy is contained in the atomic bonds. The original source of this energy is all the solar energy the prehistoric organisms trapped in their bodies eons ago. How do we make use of this bond energy then? We burn them.
Combustion, Drilling, and Refining
Combustion is the process of breaking atomic bonds to release energy in the form of light and heat. Fossil fuels have many hydrocarbons, each with numerous bonds. When they undergo combustion, they release a great deal of heat. This is the main reason why natural gas and heating oils are used extensively in the world today. However, energy in the form of heat is by nature very chaotic and disorganized. Simply burning fossil fuels is wonderful for keeping the winter chill at bay, but setting oil on fire in your washing machine won't get your clothes clean. Likewise, we can't put petroleum directly out of the ground into our cars and expect them to operate. To make use of the resource of fossil fuels, humans have developed drilling, refining, and methods to harness fossil fuel energy.
Early oil explorers relied heavily on intuition and guesswork to find the precious 'black gold.' These daring entrepreneurs were known as 'wildcatters.' A fabled technique used by the wildcatters is the 'old hat.' They would basically toss their hat up in the air and wherever it landed, they drilled. When the wildcatters got lucky, and struck oil, it would typically gush up the drill pipe, hence, a gusher. Because gushers are a safety hazard and environmental concern, oil companies today contain them. After discovering an oil field, it is the task of the oil company's engineers and technicians to get it out. Not all oil fields turn out to be gushers and even the ones that are eventually loose pressure, leaving a lot of untapped fossil fuel resource in the reservoir. Even with modern extraction techniques, 100% of the oil in any given field is still not yet recoverable.
One thing an oil company does to facilitate the extraction process is setting up what is known as a 'Christmas tree,' a system of valves and pipes that regulate oil flow and pressure. Another system used in much smaller reservoirs not worth the expense of manning with technicians is the setup of a beam pump These are also known as 'nodding donkeys;' they extract oil from small oil pools that do not contain much resource. In large oil fields, techniques such as water and gas injection are employed to maximize return of the investment. By pumping water and gas into the wells, the pressure increases allowing oil to flow upwards once more Large oil fields can be found under the sea floor as well. To exploit these fields, vast oil drilling stations, which are marvels of modern engineering, tap into these underwater deposits and bring them to the surface.
Although fossil fuels have been around long before humans even discovered fire, our prehistoric ancestors had no use for them. In the late 1800's, coal and gas were used as heat and light sources, steam locomotives as well. There were early automobiles too, but these vehicles were more of a novelty than a way of life. It wasn't until the 1940's did things change. Why the 1940's? The answer is that engineers and inventors had government support and extra incentive to develop fossil fuel technologies, war. World War II was the catalyst and not World War I because 'The War to End All Wars' was fought by men in trenches and mechanized warfare had only been developed late in the conflict. World War II had the German Blitzkrieg, or 'Lightning War.' This tactic utilized Shtuka dive bombers and Panzer tanks; German engineers enabled this, and was eventually countered by Allied technological advancements. From then on, usage and development of fossil fuels steadily rose.
The primary refining technique used to separate hydrocarbons and provide the ingredients for modern fuels is called fractional distillation. Hydrocarbons of different size and configuration usually have differences in boiling points that are large enough to use as a method of separation. By vaporizing them, they tend to float upwards until the hydrocarbons condense, which is where they are collected. Hydrocarbons as simple as butane and alcohols with few carbons are sorted along with more complex ones such as aromatics with 9 carbons. The fuels we commonly use today are a mixture of these hydrocarbons distilled from the petroleum extracted from the earth.
Fuel types and Engines
Gasoline is a highly specialized fuel that contains hydrocarbons ranging from butane to C10. It is designed for the Otto-cycle engine, also known as spark ignition or 4-stroke engine. This engine as well as others will be described in more detail later on. Some characteristics of gasoline enable the following:
1. Quick start at low temperatures
2. Fast acceleration
3. Low occurrence of stalling
4. Relatively quiet and low tendency to knock
5. Good combustion efficiencyThe next classification of fuels is the distillate fuels. They are kerosene, turbo-jet fuel, diesel, and heating oil. Kerosene was the first petroleum fuel oil to be widely used; this was before electric lights and after the days of animal and vegetable oil. Kerosene has become less popular and is no longer produced in the quantities it once was. Countries with limited access to electricity and outdoors enthusiasts still have a use for this fuel.
Turbo-jet fuel was first developed in WWII for use in airplane engines. Because of constraints on petroleum products, namely gasoline for tanks and other ground vehicles, this fuel was designed to make use of compounds not vital to gasoline production whenever possible. The result was a highly volatile fuel that led to many accidents in handling. Modern aviation fuel is still more volatile than gasoline, though it has become much safer than it previously was.
Diesel fuel and domestic heating oil are similar in composition. Domestic heating oils are not widely used in the US, though they still have limited application in underdeveloped countries. Diesel fuels are used frequently in the world today; transport vehicles such as trains, boats, trucks, and busses use diesel fuel.
Fuel oils are mainly residuals from the fractional distillation process. They are more or less the leftovers from production of other fuels. They have been and are still used in power generation plants. Because of the low quality and high pollution content fuel oils are being used less often.
Of the fuels previously listed, gasoline, turbo-jet fuel, and diesel fuel were designed for usage in engines. A fairly good, simple definition of an engine is a device that converts chemical or heat energy into mechanical energy. Engines convert fossil fuel energy into a form that we can more readily use.
The majority of engines in the world today are internal combustion engines. This type of engine is found in most machines and vehicles that run on fossil fuels. The first internal combustion engine was invented by Nicolaus August Otto. There are 4 general types of internal combustion engines that will be discussed here briefly. The first is the type designed by Mr. Otto himself, the Otto-cycle engine. These are the engines you typically find in cars. These are 4-stroke engines, named thus because it goes through 4 phases during operation: intake, compression, expansion, and exhaust. The parts of the engine directly involved in this cycle are the cylinder, the piston, the valves, and the spark plug.
· Intake-- Intake valve opesns allowing fuel/air mixture into the cylinder
· Compression-- The piston rises, reducing volume and increasing pressure
· Expansion (power stroke)-- Spark plug ignites, fuel expands pushing piston
· Exhaust-- Exhaust valve opens expelling spent fuel from cylinder
The second type of engine is known as a 2-stroke engine. These are usually placed in lawn mowers, outboard motors, and high performance recreational vehicles. There are two main differences between 4 and 2-stroke engines A 4-stroke engine causes two revolutions in one cycle whereas the 2-stroke only takes one revolution to complete its cycle. The other major difference between them is that 2-strokes require a gasoline/oil mixture as fuel. This is because the cylinder must be kept completely bathed in lubricants to prevent damage. Due to these attributes, these engines are much more compact and can generate higher revolutions per minutes and more acceleration. The problem with this design is that it is not at all fuel efficient and burning motor oil causes a lot of pollution.
Diesel engines, as you might know, require no spark plugs in the combustion process. Otherwise, the design of the diesel engine is not much different than an Otto-cycle engine. Instead of spark plugs, the diesel engine relies on compression and the heating of air in the fuel mixture to cause ignition. To achieve this, diesel fuel has a lower boiling point and does not require much heat. Diesel fuel is cheaper to make than gasoline, though its high level of pollutants require it to undergo further filtration; this drives the fuel price up.
The last type of conventional engine discussed here is the wankel rotary combustion engine, named after its inventor, Felix Wankel. Out of the engines discussed, this one is the most 'revolutionary' (excuse the pun). The wankel engine does not use pistons, instead it uses a rotor. The rotor spins and drives the shaft by expanding fuel in the housing on the sides of the rotor. The results of this engine type are as follows:
· Light weight and compact
· Smooth: no reciprocating motion
· Extended power stroke rotation: 270 degrees vs. 180 degrees of a piston
· Fewer moving parts
· Cooler combustion means fewer oxides of nitrogenThe wankel engine was used in the Mazda motorcars RX series of cars. For all the advantages of this engine, it had one major drawback, it was extremely inefficient in fuel consumption. The oil crisis in 1973 caused this engine to loose support and funding for further development to improve consumption. Currently the RX series of Mazda cars is no longer in production, however Mazda has made a RX-01 concept car. Wankel rotary engines can also be found in porches and other powerful sports cars.
Aviation fuel, the turbo-jet fuel, is used by both jet and propeller aircraft today. Prop engines are designed similar to the 4-stroke engines of cars, though the demands on these two varieties of engines are quite different. To accommodate this, prop engines are much larger and have higher power output. The distillate fuel they use is ideal for this purpose. With the inception of jet propulsion the fuels used did not change all that much. Even though it may seem that the jet engine is very different, it is still considered to be an internal combustion engine. The main components of a jet engine are the compressor, combustion chamber, and the turbine. Air flows into the compressor where it is pressurized and forced into the combustion chamber There, inside the chamber, fuel is constantly flowing in, and ignited causing an expansion of the fuel The turbine's purpose is to provide enough energy from the expelled gasses to the compressor in order to operate at peak performance. Jet engine technology has advanced greatly and there are many different types of them. Just to list a few, there are turbojet, turbofan, turboprop, turboshaft, and ramjet designs. Each have specialized uses, mostly in aviation technology.
Coal and Electricity
Fossil fuels are excellent sources of energy for out transportation needs; however they are also the primary source of electrical energy in the world today. Coal power plants account for at least 60% of our national energy and 52% of the world's demand. We, as a world, burn approximately 1.9 billion tons of coal a year to generate electricity.
How we get electrical energy from coal is by means of coal power plants. These power plants first combust the coal in large furnaces creating tremendous amounts of heat. This heat is used to evaporate water in boilers so they convert to steam. The steam expands, causing pressure to increase in the boiler. A steam turbine is placed at the exit of the boiler where it converts energy from the moving steam into mechanical energy. The rotation of this turbine is used to spin a magnet inside a power generator. This generator is a large electromagnet that encases the spinning magnet. Instead of putting electricity into the electromagnet to cause the coil to magnetize, electrons are captured from the spinning magnet and collected. The electrons are then sent to the national power grid where they are distributed as needed.
Air particles are deadly. The byproducts that form from the burning of fossil fuels are very dangerous. These small particles can exist in the air for indefinate periods of time, up to several weeks and can travel for miles. The particles, sometimes smaller than 10 microns in diameter, can reach deep within the lungs. Particles that are smaller than this can enter the blood stream, irritating the lungs and carry with them toxic substances such as heavy metals and pollutants. Over a lifetime of continued exposure, a person's ability to transfer oxygen and rid pollutants is impeded. Those affected could become afflicted with fatal asthma attacks and other serious lung conditions. the World Resources Institute reports that between the years of 2000 and 2020, 8 million deaths worldwide could possibly occur without changing present conditions. In 1990 alone, respiratory diseases were a leading cause of disabilities and illnesses worldwide. This is a global problem and requires a global solution. Because the contamination is growing at an exponential rate, minor reductions now will greatly reduce the number of lives lost in the future.
How Much is left?
So far the United States has produced the most oil at 171 billion barrels. Followed by the former Soviet Union with 125 billion and Saudi Arabia far behind in third place with 74 billion barrels. this illustrates the maturity of the United States which for many years was the world's most important producer.
The term reserves means the amounts yet to produce from known discoveried resources as of today, however it is difficult to estimate the actual amount. The country with the most reserves is Saudia Arabia with 189 Gb. This is followed by the former Soviet Union with 84 Gb. Note that the whole Middle East region has more than half of the world's oil reserves with 439 of the possible 800 billion barrels in the world.
Discovered to date is the sum of the cumulative production and the reserves. Again, see that the Middle East Gulf is in first place with 625 Gb followed by Eurasia, 267 Gb, and North America, 225 Gb. For singular countries, the order holds true with Saudi Arabia in first with the former Soviet Union and the United States rounding out the top three.
The ultimate is cumulative production when production ends. It is important to realize that there is an ultimate even if it is difficult to determine the number exactly. The Middle East region has the largest endowment with 687 Gb, followed by Eurasia with 295 Gb, and North America with 238 Gb. Saudi Arabia, 280 Gb, the FSU 230 Gb, and the United States, 210 Gb, are the three most richly endowed countries.
The undiscovered is the ultimate less the discovered. In terms of individual counrtires, the former Soviet Union (21 Gb), Iraq (19 Gb), Iran (17 Gb), and Saudi Arabia (16 Gb) have the greatest promise. Discovery rates have been falling with it currently standing at about 7 Gb a year. Most of what remains will likely be found within 10-20 years.
The remaining is the reserves plus the undiscovered. The middle east gulf continues to dominate with about half of the total, followed by Eurasia, and Latin America.
Now it is important to see which countries are close to running out of oil. This graph shows how close some countries are to the midpoint of what they can produce.
It is difficult to know the future, but these facts can put things in perspective:
Known US reserves as of 1990: 36 Gb.
The total population is about 250 million, which yields 144 barrels per person.
The consumption rate is 3 billion barrels of oil per year, which gives 12 barrels per year, per person.
144/12 is approximately 12 more years left.
In 1995, the reserve estimate dwindled to 22.5 Gb and the consumption rate remained the same.
22.5/3 means that 7.5 years remain which corresponds to the earlier prediction. On a worldwide basis, there are 400 Gb per person. The timescale when this resource is used up is dependent on the world consumption rate, a figure difficult to estimate. A worst case scenario is the "Third World" scenario which has the third world nations aspire to the US consumption rate causing the world rate to double: there would be only 400/24, meaning 17 years left. Although this is a worst case, most best case scenarios offer a resource exhaustion timescale which is at most 3-4 times this value which is 50-70 years.
Note that Saudi Arabia produces the same as the US. The US needs 600,000 wells for its production and Saudi Arabia, only 860 wells. This is because the US sits on an old oil field while Saudi Arabia is located over a very young and rich one.
With the United States importing 55% of its oil, oil spills are a serious problem. The Exxon Valdez oil spill awakened the nation as we saw its effects on television. To this day there still exsists measurable differences in the environment. Some species have not been able to recover.
Resources Effected By The Exxon Valdez Oil Spill
Description Of Injury
Status Of Recovery
Comments / Discussion
Oil Spill Morality (est.)
Sublethal / Chronic Effects
Current Population Status
Many seals were directly oiled. There was a greater decline in population in oiled vs. unoiled areas in 1989 and 1990. Population was in decline prior to the spill and recovery has still not begun possibly due to lack of preferred diet. Current population decline is 6% per year.
13 adult whales of the AB pod were missing and presumed dead in 1990 and no young were produced in 1990 or 1991. The pod gained 4 members in the following two years but since then there have been more losses than births. Some experts think that the loss of 13 whales is not related to the spill.
Several sea lions were observed with oiled pelts and oil residues were found in some tissues. It was not possible to determine population effects or cause of death of carcasses recovered. Sea lions were already in decline prior to the spill.
Yes (3,500 to 5,500)
Survival differences between oiled and unoiled areas have been noticed since the spill. Sea Otters feed in the lower intertidal zones and may still be effected by hydrocarbons in the environment.
Yes (total unknown)
Exposure to hydrocarbons and possible sublethal effects were determined, but no effects were established on population. In 1991 studies showed that exposure to hydrocarbons still remained probably from exposure through diet.
Yes (200 or more)
Productivity was disrupted in 1989 but returned to normal in 1990. Exposure to hydrocarbons was found in 1989 and it is assumed that the source, based on visual observation, was from eating oiled carcasses.
Black Oyster- catchers
Yes (120 to 150 adults)
Differences in egg sizes between oiled and unoiled areas were found in 1989. Populations declined more in oiled areas during 1989, 1990, 1991, 1992. Possibly due to exposure to hydrocarbons through diet.
Yes (170,000 to 300,000)
Measurable impacts on population were recorded in 1989, 1990, 1991, and 1992. Breeding is still reduced in some areas of the Gulf Of Alaska.
Yes (approx. 1,000)
Population declines lasted through 1992 partially due to reproductive failure. Currently studies are focusing on differences on winter survival rates between western and eastern Prince William Sound
Yes (8,000 to 12,000)
Marbled murrelets experienced a 7% population decline due to the spill. Measurable population decline was also observed before the spill and continuing today.
Yes (1,500 to 3,000)
Populations were in decline before the spill. The spill claimed between 10 and 15 percent of the population throughout the region. Hydrocarbon contamination is assumed based on the finding of hydrocarbons on the exterior of their eggs.
Yes, To Eggs & Larva
Measurable egg counts between oiled and unoiled areas were found in 1989 and 1990. In 1989, 1990, 1991 lethal and subleathal effects on eggs and larvae were found. In 1993 the population crashed due to a viral disease and fungus. Commercial fishing seasons were closed for four years between 1993 and 1997.
Yes, to eggs
Severe effects were inflicted on fry in 1989 and 1990 and continued to be high in 1991 and 1992. Fishing seasons were closed in 1989. Wide swings in returns have been documented but are more likely due to natural causes. The SEA ecosystem project is currently studying these swings.
HUMAN RESOURCES & SERVICES
Description of Injury
During 1989 emergency fishing closures were ordered in Prince William Sound, Cook Inlet, Kodiak and the Alaska Peninsula. This affected salmon, herring, crab, shrimp, rockfish, and sablefish. The 1989 closures resulted in over-escapement in the Kenai River and in the Red Lake system. Limited closures were also in effect in 1990.
Low adult sockeye returns in 1994 were a result of the over-escapement from Kenai River. Future fishing seasons may need to be closed to balance out the problem.
Recreation & Tourism
Some commercial recreation and tourism businesses were injured by the reduction in visitor spending as a result of the spill. Non-commercial recreation also decreased in some parts of the spill area. The quality of recreational experiences also decreased due to crowding, residual oil, and fewer fish and wildlife
Recreational users are benefiting from restoration projects in several ways. Habitat protection opens up land previously off limits to campers, hunters, sport fishers, and wildlife viewers while at the same time protecting the health of fish, bird and marine populations. In 1996 a 220-acre Cook Inlet bluff parcel was purchased and will be turned into a state-run campground and recreational facility. Money from the Exxon Settlement is also being used to build campgrounds, cabins, trails, bridges, buoys, food cages, fire rings, docks and interpretive signs.
*This table originated from http://library.advanced.org/10867/gather/effected_resources.shtml
Additional Energy Statistics
Natural gas accounts for 24% of the energy in the United States. Domestic production of natural gas peaked in 1973; this is because we do not import due to safety problems. Consumption of natural gas is actually flat as oppsed to increasing usage of coal and oil.
Petroleum / Natural Gas will run out in the next 50 years. 97% of fossil fuel reserves are coal. 20% of the world's coal supply is located in the United States.
Energy yield depends on how much carbon is contained in the coal. Two types dominate US reserves. Anthracite is 95% carbon and is approximately 300 million years old. Lignite is 25% carbon is nearly 150 million years old.
Deposits are around 300 feet below the surface and typically 2-8 feet thick.
Coal production has increased since 1970.
At current usage, the supply will last 1500 years. However at a 5% growth rate the supply will last only 86 years. We can expect even greater usage as other fossil fuels become scarce. Shale Oil
Shale oil deposits in the US are found in southwestern Wyoming, eastern Utah, and western Colorado. Oil shale contains kerogen which, when burned, can be converted into fuel products. The amount of shale oil deposits are significantly greater than the amount of US petroleum deposits by a factor of ten. However, economic mining requires a yield of 25 gallons of oil per ton of shale. Only 30% of the known deposits meet this criteria. Of that 30%, only 15% is recoverable under present conditions. The refinement of shale is very difficult and requires large amounts of water. The bottom line is that shale oil is not economically viable at this point.
We are currently in an energy crisis. Fossil fuels are the lifeblood of our society and for many others around the world. Our supply has a finite end, which is why we are willing to go to war for it and make friends with those we really hate. The former Soviet Union and many of the countries in the Middle East are in our good favor strictly because of their oil reserves. Our foreign aid has a legitimate purpose. Even with our newfound friends, fossil fuels will run out and the use of them will soon take the lives of many people. These are important reasons to find other means of getting the energy we need to continue our society as we know it.
So what are our options? Alternative forms of energy are currently under development even though most of them are only in their inital stages. With increased government and public support, we may be able to speed up the development of these technologies and help free ourselves from the usage of fossil fuels. Oil companies will have to be dealt with because with the future shortages of fossil fuels, they would stand to reap enormous profits. To prevent this, oil and other energy resource providing companies should be encouraged to develop these technologies for the sake of ethics if not for long-term profit gains when all fossil fuel resources are exhausted. Here are some alternative, renewable sources of energy in various stages of development:
Nuclear Fusion: Fusion involves the extraction of "heavy" hydrogen (duterium) from water and the combination of two hydrogen atoms to form helium. Although it has long been hailed as the path to unlimited energy, scientific feasibility has yet to be established. Demonstrations of technological feasibility must then follow, with mastery of materials development and system engineering looming as major hurdles.
Hydrogen: Hydrogen may become the "energy carrier of the future." Most schemes for generating hydrogen are based on the splitting of water using solar energy directly, or indirectly via electricity. Hydrogen would then be used as a substitute for natural gas. Although the technical feasibility of water splitting on a large scale has yet to be established, a "hydrogen economy" remains at least a distant possibility.
Solar Satellites: Collecting solar energy in space and transmitting it to earth via microwave is another long-range possibility. Due to the large size of the required collector, current launch and deployment costs render this scheme economically infeasible. However, future advances in space equipment may change this assessment.
Energy Plants: Rapid improvements in bioengineering may provide the basis for improving the efficency or redirecting the end products of photosynthetic processes to produce commercial fuels such as hydrogen. At this time, scientific feasibility of developing "super species" remains to be established.
Combinations: Concepts for combining end uses and supply generation facilities to better utilize waste heat already are being employed. These include cogeneraton of steam and electricity and district heating. Future combinations may include the use of nuclear energy to generate heat for coal gasification and liquification. The requisite hydrogen for synthetic fuel production may be provided by splitting water with solar energy. Other hybrid systems may emerge as the component parts become practical.
With these options we can help phase out our dependency on fossil fuels and find clean, efficent, sources of power. Keep in mind that these are not the only options known today and that there are others that have not even been conceived. Using these other sources, we can guarantee a healthy and prosperous future.