~ Mother Earth ~
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Fox Glacier
The Fox Glacier or Te Moeka o Tuawe is a glacier located in Westland National Park on the West Coast of New Zealand's South Island. It was named in 1872 after a visit by the then Prime Minister of New Zealand, Sir William Fox. Although retreating throughout most of the last 100 years, it has been advancing since 1985 at an average of about 40 cm a day.
Ice cave in the terminal face of Fox Glacier in Westland National Park on the West Coast of New Zealand's South Island.
Fed by four alpine glaciers, Fox Glacier falls 2,600 m on its 13 km journey from the Southern Alps down to the coast. Like the nearby Franz Josef Glacier, it is one of the most accessible glaciers in the world, with its terminal face an easy 5 km walk from Fox Glacier village/Weheka. The outflow of the glacier forms the Fox River.
Fox Glacier village/Weheka functions mainly as a service centre for tourists. It also services the local farming community.
Issue #115 -
Northridge earthquake
The 1994 Northridge earthquake occurred on January 17, 1994 at 4:30:55 AM Pacific Standard Time in the city of Los Angeles, California. This earthquake was considered moderate, with a moment magnitude of 6.7, but was the most monetarily costly quake in United States history. The Guinness Book of World Records rates the earthquake at a 7.5.
Aftermath of the 1994 Northridge earthquake. The underpass of the 10 Freeway at La Cienega Blvd. It shows the collapsed section of the freeway.
The epicenter was in the San Fernando Valley, originally believed to be in the community of Northridge (later shown to actually have occurred within the neighboring community of Reseda), about 32 km (20 mi) northwest of downtown Los Angeles. The National Geophysical Data Center places the epicenter's geographical coordinates at 34.213 N and 118.537 W, which is at the end of Elkwood St., just east of Baird Av.
Damage occurred up to 77 km (52 mi) away, with the most damage in the west San Fernando Valley and the city of Santa Monica. Fifty-seven people were killed, and over 1,500 were seriously injured. Major freeway damage occurred up to 32 km (20 mi) from the epicenter. Portions of Interstate 10 (the Santa Monica Freeway) and California State Highway 14 (the Antelope Valley Freeway) collapsed and had to be rebuilt.
The support columns were crushed into giant metal cage-like states.
This quake was unusual because the epicenter was within a major metropolitan area. Although several commercial buildings collapsed, loss of life was minimized because of the early morning hour of the quake, and it occurred on the birthdate (observed) of Martin Luther King, Jr., a federal holiday. Also, because of known seismic activity in California, area building codes dictate that buildings incorporate structural design intended to reduce the risk of structural collapse due to earthquakes. As it turned out, one of the few multi-family buildings to collapse had not been built to code.
Through investigation of damaged buildings, it was discovered that structural steel did not perform as well as expected. Because nobody anticipated that steel would fail at the rate that it did, buildings that were not expected to have major damage were red-tagged many months after the quake, when the inspectors finally got to them. This new information on the nature of earthquake damage resulted in even more stringent building codes.
The freeway bent even before the collapsed section.
The quake produced unusually strong thrust, with accelerations in the range of 1.0 g over a large area. While most of the damage was caused by shaking, some damage was also caused by fire and by ground deformation. In some areas the ground surface was permanently uplifted by up to 50 cm (20 in).
This was the third very destructive earthquake to occur in California in 23 years. The first was the Mw 6.6 San Fernando (Sylmar) Earthquake, affecting the same area in 1971; the second was the Mw 6.9 (Richter magnitude 7.1), 1989 Loma Prieta earthquake south of San Francisco. The 1994 event is the most damaging earthquake to strike the United States since the San Francisco earthquake of 1906. In terms of financial loss, the earthquake is also one of the worst natural disasters in U.S. history, comparable to Hurricane Andrew in 1992.
Several key hospitals suffered severe structural damage and were rendered unusable after the earthquake. Not only were they unable to serve their local neighborhoods, they had to transfer out their inpatient populations, which further increased the burden on nearby hospitals that were still operational. As a result, the state legislature passed a law requiring all California hospitals to ensure that their acute care units and emergency rooms are in earthquake-proof structures by January 1, 2005.
Issue #116 -
Aleutian Range
The Aleutian Range is the mountain range of the Alaska Peninsula in southeast Alaska. It is especially notable for its large number of active volcanoes. The mainland part of the range is about 1,000 km (600 mi) long; the Aleutian Islands are (geologically) a partially submerged western extension of the range that stretches for another 1,600 km (1,000 mi).
Map showing volcanoes along the Aleutian Range on the Alaska Peninsula
The range is almost entirely roadless wilderness, and Katmai National Park and Preserve must be reached by boat or plane.
Mountains
- Mount Redoubt (3,109 m)
- Iliamna Volcano (3,054 m)
- Mount Shishaldin (2,857 m)
- Mount Pavlof (2,715 m)
- Mount Veniaminof (2,508 m)
- Isanotski Peaks (2,446 m)
- Mount Denison (2,318 m)
- Mount Douglas (2,153 m)
- Mount Chiginagak (2,134 m)
- Double Peak (2,078 m)
- Mount Katmai (2,047 m)
- Makushin Volcano (2,036 m)
- Pogromni (2,002 m)
Issue #117 -
Dew
Dew is the term for small droplets of water that appear on thin objects in the morning or evening. This is a form of condensation. Dew results from atmospheric moisture that condenses after a warm day and appears during the night on cooled surfaces as small drops. The cool surfaces cool the nearby air, decreasing the amount of humidity (dissolved moisture) the local air can hold. The extra vapor condenses (precipitates out of solution in the air). When temperatures are low enough, dew will take the form of ice; this form is called frost.
Dew on leaves of grass
As dew is related to the temperature of surface, in late summer it is formed most easily on surfaces which are not warmed by conducted heat from deep ground, such as railings, car roofs and bridges.
Dew on a spider web
Culturally, dew is often associated with purity and freshness. This is evidenced by the names of certain popular beverages such as Mountain Dew and Sierra Mist.
Issue #118 -
Park Guell
Parc Güell (Park Guell) is a garden complex with architectural elements situated on the hill of El Carmel in the Grà cia district of Barcelona, Spain. It was designed by the Catalan architect Antoni Gaudà and built in the years 1900 to 1914. It is one of the UNESCO World Heritage Sites.
The entrance to the Park Guell
The Park was originally part of a commercially unsuccessful housing site. It has been converted into a municipal garden. It can be reached by underground, although the stations are at a certain distance, by the regular buses, or best by the tourist buses. While the Park is free, GaudÃ's house - containing furniture that he designed - can be visited at a cost.
The design of the Park is clearly the work of an architect and GaudÃ's unique style is also easily distinguishable. Wavy, lava-like shapes, at places tree-like or in form of Doric columns or stalactites, sometimes lavishly decorated with ornaments of broken ceramic fragments. The landscaping of the Park is largely in tune with the natural terrain; steep slopes and cliffs have been allowed to remain, with winding paths, cuttings and grottoes adding to the natural feel.
GaudÃ's mosaic work on the main terrace
Although it sounds unlikely, the place is skillfully designed and composed to bring the peace and calm that one would expect from a park. The buildings, though very original and remarkable, are relatively (remembering other Gaudà buildings) inconspicuous. They have fantastically shaped roofs with unusual pinnacles. The focal point of the park is the main terrace, surrounded by a long bench in the form of a sea serpent. Gaudà used a naked man, sitting in clay, to design the bench. The curves form a number of enclaves, creating a more social atmosphere.
The Gaudà style is evident in the supporting columns of the walkway above.
The large cross at the Park's high-point offers the most complete view of Barcelona. It is possible to view the main city in panaroma, with la Sagrada Familia and the Montjuïc area visible at a distance.
Issue #119 -
Vasco da Gama
Vasco da Gama (c. 1469–December 24, 1524) was a Portuguese explorer who was the first person to sail directly from Europe to India.
Vasco da Gama
Life
From the early 15th century, the nautical school of Henry the Navigator had been extending Portuguese knowledge of the coast of Africa. From the 1460s, the goal had become one of rounding that continent's southern extremity and gaining easier access to the riches of India (mainly black pepper and other spices) through a reliable sea route instead of the costly and unsafe overland route.
Da Gama was born in Sines. He was slightly younger than 20 years old as these long-term plans were coming to fruition. Bartolomeu Dias had returned from rounding the Cape of Good Hope and exploring as far as the Fish River in modern-day South Africa, while Pero da Covilhã in India had explored south for some of the distance intervening between subcontinent and the end of explorations. It remained only for the two segments to be joined into one voyage.
This task was given to Da Gama's father, Estevão da Gama, but he died before he could begin. Vasco was then given the job on the strength of his work for the Portuguese crown along the Gold Coast of Africa. On July 8, 1497 four ships (the São Gabriel, the São Rafael, whose commander was his brother Paulo da Gama, the Berrio, and a storage ship of unknown name) left Lisbon and the voyage began.
By December 16 they had passed the Fish River and continued on into waters unknown to Europeans. With Christmas pending they gave the coast they were passing the name Natal (Christmas in Portuguese), which it retains to this day. By January they had reached modern-day Mozambique, Arab-controlled territory on the East African coast that was part of the Indian Ocean's network of trade. Having got that far, da Gama was able to employ a pilot at Malindi, who brought the expedition the rest of the way to Calicut (the exact Malayalam name is Kozhikode) on the southwest coast of India on May 20, 1498. Sometimes violent negotiations with the local ruler (the Samoothiri Raja, usually anglicized as Zamorin) ensued in the teeth of resistance from Arab merchants. Eventually da Gama was able to gain an ambiguous letter of concession for trading rights, but had to sail off without warning after the Zamorin insisted on his leaving behind all his goods as collateral. Da Gama kept his goods, but left behind a few Portuguese with orders to start a trading post.
Vasco da Gama on board a boat
Upon his return to Portugal in September 1499, da Gama was richly rewarded as the man who had brought to fruition a plan that had taken eighty years. He was given the title "Admiral of the Indian Ocean", and on February 12, 1502 he sailed again with a fleet of twenty warships to enforce Portuguese interests. Pedro �lvares Cabral had been sent out two years earlier (on which voyage he incidentally discovered Brazil, though some claim this it was intentional) and found that those at the trading post had been murdered, encountered further resistance and bombarded Calicut.
Da Gama assaulted and exacted tribute from the East African Arabian port of Kilwa, which had been one of those involved with frustrating the Portuguese; he played privateer amongst Arab merchant ships; and then finally smashed a Calicut fleet of twenty-nine ships and essentially conquered that port city. In return for peace, he received valuable trade concessions and a vast quantity of plunder that put him in extremely good favor with the Portuguese crown. Returning to Portugal, he was made Count Vidigueira out of lands that had previously belonged to the royal Bragança family.
Having acquired a fearsome reputation as a "fixer" of problems that arose in India, he was sent to the subcontinent once more in 1524. The intention was that he was to replace the incompetent Eduardo de Menezes as viceroy of the Portuguese possessions, but he died not long after arriving in Calicut. After burial for some time at St.Francis Church, Fort Kochi, Kochi, India, his remains were returned to Portugal in 1539 and re-interred in Vidigueira.
As much as anyone after Henry the Navigator, da Gama was responsible for Portugal's success as an early colonizing power. Besides the first voyage itself, it was his astute mix of politics and war on the other side of the world that placed Portugal in a prominent position in the Indian Ocean trade. The Portuguese "national epic", the LusÃadas of LuÃs Vaz de Camões largely concerns Vasco da Gama's voyages.
Issue #120 -
Olympia
Olympia (Greek: OlympÃ'a or Olýmpia, older transliterations, Olimpia, Olimbia), a city of ancient Greece in Elis, is known for having been the site of the Olympic Games in classical times, comparable in importance to the Pythian Games held in Delphi. Both games were held every olympiad (i.e. every four years), the Olympic Games dating back at least as far as 776 BC. In 394 CE emperor Theodosius I abolished them.
Ruins of the Temple of Zeus at Olympia, Greece
Olympia is also known for its gigantic ivory and gold statue of Zeus, made by Phidias, which was one of the Seven Wonders of the Ancient World. Very close to the temple of Zeus (see photo of ruins below) which housed this statue, the studio of Phidias was excavated in the 1950s. Evidence found there such as sculptor's tools, corroborates this opinion.
Excavation of the Olympia temple district and its surroundings began with a French expedition in 1829. German archaeologists continued the work in the latter part of the 19th century. The latter group uncovered, intact, the Hermes of Praxiteles statue, among other artifacts. In the middle of the 20th Century, the stadium where the running contests took place was excavated.
The Olympic flame of the modern-day Olympic Games is lit by reflection of sunlight in a parabolic mirror at the restored Olympia stadium and then transported by a torch to the place where the games are held.
When the modern Olympics came to Athens in 2004, the men's and women's shot put competition was held at the restored stadium.
The ancient ruins sits north of the Alfeios River and lies next to Cronius or Kronios hill (the hill of Kronos, or Saturn). Kladeos, a tributary of Alfeios, flows around the area.
The town has a school and a square (plateia). Tourism is popular throughout the late-20th century. The city has a train station and is the easternmost terminus of the line of Olympia-Pyrgos (Ilia). The train station which the freight yard is west of it is about 300 m east of the town centre.
View onto the training ground from a room of the palestra.
It is linked by GR-74 and the new road was opened in the 1980s, the next stretch N and NE of Olympia will open in around 2005. Distance from Pyrgos is 20 km E (old: 21 km), about 50 km SW of Lampeia, W of Tripoli and Arcadia and 4 km north of Krestena and N of Kyparissia and Messenia. The highway passed north of the ancient ruins.
A reservoir is located 2 km southwest damming up the Alfeios river and has a road from Olympia and Krestena which in the late-1990s has been closed.
The area is hilly and mountains, most of the area within Olympia is forested.
Issue #121 -
Coventry Canal
The Coventry Canal is a narrow Canal in England which travels for 38 miles (65 km) between Coventry and Fradley Junction, just north of Lichfield, where it joins the Trent and Mersey Canal. It also runs through the towns of Bedworth, Nuneaton, Atherstone, Polesworth and Tamworth.
The Coventry Canal forms part of the Warwickshire ring.
Coventry Canal near Fradley
The Route
The canal begins at a basin in the centre of Coventry, and runs north. Just north of Coventry, it forms a junction with the Oxford Canal at Hawkesbury junction, also known as "Sutton Stop". A few miles further north just outside Bedworth it connects to the Ashby Canal, then runs north-west for a number of miles through Nuneaton, Atherstone and Polesworth. At Tamworth its splits into the Birmingham & Fazeley Canal. The Coventry canal finishes at Fradley junction where it joins the Trent and Mersey Canal.
History
The Coventry Canal Company was formed in 1768 and James Brindley was commissioned to build it; work started on the canal in the December of that year.
Due to the high standards of construction demanded by Brindley, by the time the canal had reached Atherstone in 1769, the canal company had run out of money, and Brindley was sacked.
The canal remained half finished for another seventeen years, but was finally completed and opened in 1789. The canal was for many years an important artery of trade, and was nationalised in 1948, and taken over by British Waterways.
Issue #122 -
Igloo
An igloo (Inuktitut iglu, "house"), translated sometimes as snowhouse, is a shelter constructed from blocks of snow, generally in the form of a dome. Igloos are most commonly associated with the indigenous Inuit of Canada's far north, where they were used as temporary shelters by hunters during the winter.
Igloo
The snow used to build an igloo must have sufficient structural strength to be cut and stacked in the appropriate manner. The best snow to use for this purpose is snow which has been blown by wind, which can serve to compact and interlock the ice crystals. The hole left in the snow where the blocks are cut from is usually used as the lower half of the shelter. Sometimes, a short tunnel is constructed at the entrance to reduce wind and heat loss when the door is opened. Due to snow's excellent insulative properties, inhabited igloos are surprisingly comfortable inside.
Central Eskimos, especially those around the Davis Strait, line the living area with skin, which can increase the temperature within from around 2°C to 10-20°C.
Architecturally, the igloo is unique in that it is a dome that can be raised out of independent blocks leaning on each other and polished to fit without an existing supporting structure.
Sideview diagram of an Igloo: opening to the right
Because "igloo", or iglu in standard orthography, is simply the Inuktitut word for a house of any kind, since the twentieth century a snowhouse in Inuktitut is frequently called an igluvigaq, or igluvigait in plural, in distinction.
Other kinds of snowhouses
For fun, or for winter camping and survival purposes, it is possible to construct a simpler but similar kind of snow shelter by simply creating a large pile of snow and excavating the inside. The snow need not be of the same quality, and the construction is easier (less experience needed). Such shelters are usually not as sturdy and permanent as proper igloos.
A nice trick to make the building of a snowhouse much quicker and less labour intense is to first make a pile of (cardboard) boxes and then cover the box pile with snow. Then cut open "the door" and pull out the boxes. This means one needs to use much less snow or one can build a much bigger snowhouse. (Old cardboard boxes can usually be acquired at the local supermarket if one asks nicely.)
To make the snowhouse much more robust and safer it is recommended to pour water over it so it gets covered in ice. This makes it harder and sturdier and also makes it slippery, which discourages kids from climbing on top of if. Kids climbing on the house are usually the only reason why snowhouses collapse. A collapsing snowhouse can be very dangerous if kids get caught inside. (By the way, pour the water after pulling out the boxes since it is very hard to cut open a door in an icy house.)
Issue #123 -
The World
The World is an archipelago of artificial islands, shaped like the continents of the Earth, being constructed off the coast of Dubai. The project is inspired by the artificial Palm Islands also being built in Dubai. The World will consist of 250 to 300 smaller private artificial islands divided into four categories - private homes, estate homes, dream resorts, and community islands. The entire project is slated for completion in 2008.
The World Islands
Each island ranges from 250,000 to 900,000 square feet (23,226m² to 83,613m²) in size, with 50 to 100 metres of water between each island. The development covers an area of 9 kilometers in length and 6 kilometers in width, surrounded by an oval breakwater. The only means of transportation between the islands will be by boat and helicopter. Each island will cost an estimated average of $25 million (USD).
It is built, and is owned, by Al Nakheel Properties (Nakheel Corp).
It is located 4 kilometers off the shore of Jumeirah, close to The Palm, Jumeirah, between Burj Al Arab and Port Rashid of Dubai, United Arab Emirates.
The World is sometimes mistakenly referred to as The Palm World.
Official website
Issue #124 -
Itaipu
Itaipu (Guarani: Itaipú; pronounced [itaj'pu]) is a dam that includes the largest hydroelectric power plant in the world. It is situated between Brazil and Paraguay along the Paraná River.
Itaipu Dam
The plant consists of 18 generator units of 700 MW (Megawatts) each, allowing for a total output of 12,600 MW of power, The first generators started running in May 1984 and the final generator started running on April 9, 1991. Although it is not the largest dam in the world, it has the largest generating capacity and produces the most electricity. Its generating capacity (but not its annual production of electricity) will be surpassed by China's Three Gorges Dam. Two more generator units are currently being built. When finished in the first half of 2005, Itaipu will be capable of a total output of 14,000 MW of power. The name "Itaipu" is derived from the Tupi Guarani language and means "singing stones".
It has been declared one of the modern Seven Wonders of the World by the American Society of Civil Engineers.
Division between Brazil and Paraguay
As with the division of financing, half of the generators are owned by Brazil and the other half by Paraguay. However, Paraguay sells the majority of its power to Brazil (and therefore has not had difficulty in paying for the project). Even in this configuration, the plant supplies 25% of the power consumed by Brazil and 90% of that consumed by Paraguay. Furthermore, this electricity for Paraguay is sold very cheaply and so although it is poor, its citizens can afford abundant lighting. On the other hand, Itaipu was built during the corrupt Stroessner dictatorship and so a small number of families owning large construction businesses benefitted significantly at the expense of the general population.
Power transmission
The power generated by the generators on the Paraguay side is done at a frequency of 50 Hertz, as 50 Hertz is the grid frequency of Paraguay. The generators on the Brazilian side run with the grid frequency of Brazil, which is 60 Hertz. Because Paraguay cannot consume all the energy produced by its generators, a part of it is transfered via the HVDC Itaipu to the area of São Paulo. The power generated by the Brazilian generators is transfered by 765 kV three phase AC lines to São Paulo.
Issue #125 -
Rann of Kutch
The Rann of Kutch is a seasonally marshy region located in the Thar Desert biogeographic province in Gujarat state of northwestern India, which borders the Sind region of Pakistan. The name "Rann" comes from the Hindi word ran meaning "salt marsh". Kutch is the name of the district wherein it is situated. The Rann of Kutch comprises some 10,000 square miles between the Gulf of Kutch and the mouth of the Indus River in southern Pakistan. The Luni River, which originates in Rajasthan, empties into the northeast corner of the Rann.
Rann of Kutch on the Top Left. Image from NASA Earth Observatory.
In India's summer monsoon, the flat desert of salty clay and mudflats, averaging 15 m above sea level, fill with standing waters, interspersed with sandy islets of thorny scrub, breeding grounds for some of the largest flocks of Greater and Lesser flamingoes.
The area was a vast shallows of the Arabian Sea until continuing geological uplift closed off the connection with the sea, creating a vast lake that was still navigable during the time of Alexander the Great. The Ghaggar River, which presently empties into the desert of northern Rajasthan, formerly emptied into the Rann of Kutch, but the lower reaches of the river dried up as its upstream tributaries were captured by the Indus and Ganges thousands of years ago. Traces of the delta and its distributary channels on the northern boundary of the Rann of Kutch were documented by the Geologic Survey of India in 2000.
This inhospitable salty lowland, rich in natural gas and a resting site for migratory Siberian birds, is part of India and Pakistan's ongoing border dispute concerning Sir Creek. In April 1965, a dispute there contributed to the Indo-Pakistani War of 1965, when fighting broke out between India and Pakistan. Later the same year, British Prime Minister Harold Wilson successfully persuaded both countries to end hostilities and set up a tribunal to resolve the dispute. The verdict saw Pakistan gaining 900 km² of the Rann of Kutch. Further border disputes broke out in 1971.
The Rann is also famous for the Indian Wild Ass sanctuary, the Little Rann of Kutch, where the last of three species of Asiatic Wild Ass (Equus hemionus khur or khar), the only ones in Asia, still exists along with wolves, foxes, jackals, chinkara gazelles, nilgai antelope and blackbucks. The Rann of Kutch is also the only place in India which plays host to migrating flamingoes.
Issue #126 -
Copper Canyon
The Copper Canyon (Spanish: Barranca del Cobre) is a canyon system in the Sierra Tarahumara in the southwestern part of the state of Chihuahua in Mexico. This canyon system is larger and deeper than the Grand Canyon in the neighbouring United States, although the Grand Canyon is larger overall than any of the individual canyons of the Copper Canyon system.
The Copper Canyon
The system is transversed by the Chihuahua al PacÃfico railroad, known by the nickname "Chepe." It is both an important transportation system for locals and a draw for tourists.
There are actually six separate canyons in the Copper Canyon system, each of which is spectacular in its own right. Mexico established the Parque Nacional Barranca del Cobre (Copper Canyon National Park) to showcase this remote but beautiful area.
Issue #127 -
Peninsula Valdés
Peninsula Valdés is a peninsula along the Atlantic coast in the Chubut Province, Argentina. Its size is about 3,625 km².
Peninsula Valdés, photo taken during shuttle mission STS-68
Most of the peninsula is barren land with some salt water lakes. The largest of these lakes is at an elevation of about 40 m below sea level, the lowest elevation in Argentina and South America.
Peninsula Valdés is an important nature reserve which was listed as World Heritage Site by the UNESCO in 1999. The coastline is inhabited by marine mammals, like eared seals and elephant seals. Southern right whales can be found in the Golfo Nuevo between the peninsula and the Patagonian mainland. These baleen whales come here during the second half of the year, for mating and reproduction, because the water in the gulf is quieter and warmer than in the open sea. Orcas can be found off the coast, in the open sea off the peninsula. The inner part of the peninsula is inhabited by ñandúes, guanacos and maras.
Issue #128 -
Dolomite
Dolomite is a mineral (formula: CaMg(CO3)2) consisting of a calcium magnesium carbonate found in crystals and in beds as dolostone. A pure form of dolostone would be rare, however; it usually intergrades with limestone and is referred to as dolomitic limestone, or in old U. S. geologic literature as magnesian limestone.
Dolomite has physical properties similar to those of the mineral calcite, but is less soluble in hydrochloric acid.
Dolomite from Touissite, Morocco
There is uncertainty as to the cause of its formation, as vast deposits are present in ancient rock, but it is very rarely found being produced in modern environments. This is referred to as the "Dolomite Problem". Dolomite accounts for about 10% of all sedimentary rock, including much that would have been produced near the surface of the Earth. However, experiments have only been able to synthesize dolomite under the high temperatures and pressures present in deeper layers.
One interesting reported case was the formation of dolomite in the kidneys of a dalmatian dog. This was believed to be due to chemical processes triggered by bacteria.
Recent research has found modern dolomite formation under anaerobic conditions in supersaturated saline lagoons along the Rio de Janeiro coast of Brazil, namely, Lagoa Vermelha and Brejo do Espinho. Similar processes have been discovered in the Coorong region of South Australia.
Dolomite is now thought to develop under these conditions only with the help of sulfate-reducing bacteria. The fact that conditions were better for the survival of these bacteria on the ancient Earth may explain the "Dolomite Problem". This joins other research in pointing out many new interesting links between large-scale geology and small-scale microbiology.
Dolomite is used as an ornamental stone and as a raw material for the manufacture of cement. It is also a source of magnesium oxide.
Issue #129 -
Paracel Islands
The Paracel Islands or Xisha Islands are a group of small islands and reefs in the South China Sea and part of the South China Sea Islands, about one-third of the way from central Vietnam to the northern Philippines.
Paracel Islands
The Paracel Islands are surrounded by productive fishing grounds and by potential oil and gas reserves. In 1932, French Indochina annexed the islands and set up a weather station on Pattle Island; maintenance was continued by its successor, Vietnam. The People's Republic of China has occupied the Paracel Islands since January 19, 1974, when its troops seized a South Vietnamese garrison occupying the western islands. The islands are claimed by the Republic of China (Taiwan) and Vietnam.
Paracel Islands' location relative to the claimants
The islands have no indigenous inhabitants. The PRC announced plans in 1997 to open the islands for tourism. The small Chinese port facilities on Woody Island and Duncan Island are being expanded. There is one airport.
- Geographic coordinates: 16°30' N 112°00' E
- Coastline: 518 km
- Climate: tropical
- Elevation extremes:
-- lowest point: South China Sea, 0 m
-- highest point: unnamed location on Rocky Island, 14 m
- Natural resources: none
- Natural hazards: typhoons
Issue #130 -
Salisbury Plain
Salisbury Plain is a 300 sq mi (780 km²) chalk plateau in central southern England. The plain is sparsely populated and the principal land uses are arable agriculture, chalk grassland, military institutions, and a few small areas of beech and coniferous woodland. The plain is the largest remaining area of calcareous grassland in northwest Europe. Its highest point is Walbury Hill, at 297 m above sea level.
Stonehenge on the Salisbury Plain
The Wylye, Avon and Bourne valleys cut through the plain. They have narrow flood plains, steep sides, and relatively high population density. All three valleys flow down to Salisbury where the rivers meet. Durrington and Amesbury are the only towns on the plain, though there are a number of small villages and hamlets. The A303 cuts across the plain, and a tunnel is soon to be constructed to protect Stonehenge from the damage done by the huge volume of traffic which passes just metres from the stones.
The Hampshire Downs and the Berkshire and Marlborough Downs are chalk downland to the east and north of Salisbury Plain, and the Dorset Downs and Cranborne Chase are to the southwest. In the west and northwest the geology is mainly of the clays and limestones of the Blackmore Vale, Avon Vale and Vale of Wardour. To the south is the New Forest.
Salisbury Plain has featured in the writings of William Wordsworth, Thomas Hardy, William Henry Hudson, and A.G. Street and in the paintings of Constable.
The plain is one of the Ministry of Defence and NATO's principal training grounds because of the sparse population. Because of the large training areas inaccessible to the public, the plain is also a wildlife haven, and home to two National Nature Reserves, but there is concern that the low level of grazing on the plain could allow scrub to encroach on the grassland.
The plain is also home to DSTL Porton Down, a laboratory whose work is shrouded in secrecy.
History
Salisbury Plain is famous for its history. In Neolithic times there was an extensive population and much of the original vegetation had been cleared. The population was centred around the causeway camps of Whitesheet Hill and Robin Hood's Ball. By 2200 BC, Stonehenge and Avebury had become a focus for building, including a large quantity of round barrows and long barrows. Around 600 BC, large Bronze Age hill forts were constructed at Scratchbury and Battlesbury. Roman roads are visible features, probably serving a settlement near Old Sarum. Villas are sparse, however, and Anglo-Saxon place names suggest that the plain was mostly a grain producing imperial estate.
In the sixth century Anglo-Saxon incomers built planned settlements in the valleys surrounded by strip lychetts, with the downland left as sheep walks. To the south is the city of Salisbury, whose 13 and 14th century cathedral is famous for having the tallest spire in the country, and the building was, for centuries, the tallest building in Britain. The cathedral is evidence of the prosperity the wool and cloth trade bought to the area. In the post-Medieval period, the system of floated flood meadows was developed, and large manors and estates developed around Salisbury. In the mid-19th century the wool and cloth industry began to decline, leading to a decline in the population and change in land use from sheep farming to agriculture and military use. Wiltshire became one of the poorest counties in England during this period of decline. There are a number of chalk carvings on the plain, of which the most famous is the Westbury White Horse. The Kennet and Avon Canal runs to the north of the plain, through the Vale of Pewsey.
In 1896 George Kemp and Marconi experimented with wireless telegraphy on Salisbury Plain, and achieved good results over a distance of 1¾ miles.
Issue #131 -
Rain
Rain is a form of precipitation, other forms of which include snow, sleet, hail, and dew. Rain forms when separate drops of water fall to the Earth's surface from clouds. Not all rain reaches the surface, however; some evaporates while falling through dry air. When none of it reaches the ground, it is a precipitation called virga.
Rain falling
Rain in nature
Rain plays a major role in the hydrologic cycle in which moisture from the oceans evaporates, condenses into clouds, precipitates back to earth, and eventually returns to the ocean via streams and rivers to repeat the cycle again. There is also a small amount of water vapor that respires from plants and evaporates to join other water molecules in condensing into clouds
The amount of rainfall is measured using a rain gauge. It is expressed as the depth of water that collects on a flat surface, and can be measured to the nearest 0.25 mm or 0.01 in. It is sometimes expressed in litres per square metre (1 L/m² = 1 mm).
Raindrops on grass
Falling raindrops are often depicted in cartoons as "tear-shaped", round at the bottom and narrowing towards the top, but this is incorrect (only drops of water dripping from some sources are tear-shaped at the moment of formation). Small raindrops are nearly spherical. Larger ones become increasingly flattened, like hamburger buns; very large ones are shaped like parachutes. On average, raindrops are 1 to 2 mm in diameter. The biggest raindrops on Earth were recorded over Brazil and the Marshall Islands in 2004 - some of them were as large as 10 mm. The large size is explained by condensation on large smoke particles or by collisions between drops in small regions with particularly high content of liquid water.
Generally, rain has a pH slightly under 6, simply from absorption of atmospheric carbon dioxide, which dissociates in the droplet to form minute quantities of carbonic acid. In some desert areas, airborne dust contains enough calcium carbonate to counter the natural acidity of precipitation, and rainfall can be neutral or even alkaline. Rain below pH 5.6 is considered acid rain.
Culture
Cultural attitudes towards rain differ across the world. In the largely temperate Western world, rain traditionally has a sad and negative connotation - reflected in children's rhymes like Rain Rain Go Away - in contrast to the bright and happy sun. In dry places such as India, the rain is greeted with euphoria.
Several cultures have developed means of dealing with rain and have developed numerous protection devices such as umbrellas and raincoats, and diversion devices such as gutters and storm drains. Many people also prefer to stay inside on rainy days, especially in tropical climates where rain is usually accompanied by thunderstorms or rain is extremely heavy (monsoon). Rain may be collected for drinking water, or used as greywater. Excessive rain, particularly after a dry period has hardened the soil so that it cannot absorb water, can cause floods.
Raindrops on an umbrella
Many people find the scent smelt during and immediately after rain especially pleasant or distinctive. The source of this smell is petrichor, an oil produced by plants, then absorbed by rocks and soil, and later released into the air during rainfall.
Issue #132 -
Sea floor spreading
Sea floor spreading is a part of the theory of plate tectonics. Sea floor spreading is the process by which continental drift occurs. This mechanism, which is a more accurate version of Alfred Wegener's original drift of continents that "plow" through the sea, was proposed by Harry Hess from Princeton University in the 1960s. This phenomenon is known to be caused by convection currents in the plastic, very weak upper mantle, or asthenosphere.
The age of oceanic crust. Youngest crust is along spreading centers created by sea floor spreading.
Incipient spreading
In the general case, sea floor spreading starts as a rift in a continental land mass, similar to the Red Sea-East Africa Rift System today. The process starts with heating at the base of the continental crust which causes it to become more plastic and less dense. Because less dense objects rise in relation to more dense objects, the area being heated becomes a broad dome. As the crust bows upward, fractures occur that gradually grow into rifts. The typical rift system consists of three rift arms at approximately 120 degree angles. These areas are named triple junctions and can be found in several places across the world today.
Early spreading
If spreading continues past the incipient stage described above, two of the rift arms will open while the third arm stops opening and becomes a 'failed rift'. As the two active rifts continue to open, eventually the continental crust is attenuated as far as it will stretch. At this point basaltic oceanic crust begins to form between the separating continental fragments. When one of the rifts opens into the existing ocean, the rift system is flooded with seawater and becomes a new sea. The Red Sea is an example of a new arm of the sea, and the East Africa rift is a "failed" arm that is opening somewhat more slowly than the other two arms. During this period of initial flooding the new sea is sensitive to changes in climate and eustasy. As a result the new sea will evaporate (partially or completely) several times before the elevation of the rift valley has been lowered to the point that the sea becomes stable. During this period of evaporation large evaporite deposits will be made in the rift valley. Later these deposits have the potential to become hydrocarbon seals and are of particular interest to petroleum geologists.
Sea floor spreading can stop at any time in the process, but if it continues far enough that the continent is completely severed a new ocean basin is created. The Red Sea has not yet completely split Arabia from Africa, but a similar feature can be found on the other side of Africa that has broken completely free. South America once fit into the area of the Niger Delta. The Niger River has formed in the failed rift arm of the triple junction.
Continued spreading and subduction
The new oceanic crust is quite hot relative to old oceanic crust, so the new oceanic basin is shallower than older oceanic basins. Since the diameter of the earth remains relatively constant despite the production of new crust a mechanism must exist by which crust is also destroyed. The destruction of oceanic crust occurs at subduction zones where oceanic crust is forced under either continental crust or oceanic crust. Today, the Atlantic basin is actively spreading at the Mid-Atlantic Ridge. Only a small portion of the oceanic crust produced in the Atlantic is subducted. However, the plates making up the Pacific Ocean are experiencing subduction along many of their boundaries which causes the volcanic activity in what has been termed the Ring of Fire. The Pacific is also home to one of the world's most active spreading centers (the East Pacific Rise (EPR)) with spreading rates of up to 13 cm/yr. The Mid-Atlantic Ridge is a "textbook" slow spreading center while the EPR is used as an example of fast spreading. The differences in spreading rates affect not only the geometries of the ridges but also the geochemistry of the basalts that are produced.
Since the new oceanic basins are shallower than the old oceanic basins, the total capacity of the world's ocean basins decreases during times of active sea floor spreading. During the opening of the Atlantic Ocean, sea level was so high that a Western Interior Seaway formed across North America from the Gulf of Mexico to the Arctic Ocean.
Debate and search for mechanism
At the Mid-Atlantic Ridge (and other places), material from the upper mantle rises through the faults between oceanic plates to form new crust as the plates move away from each other, a phenomenon first observed as continental drift. When Alfred Wegener first presented a hypothesis of continental drift in 1912, conservative geologists, especially in North America, demanded to know where the motive force could possibly lie. Discoveries of the earth's great fiery welts, like the mid-Atlantic Ridge and the East Pacific Rise have provided the explanation.
It is still a matter of some debate whether seafloor spreading is driven primarily by the force of rising magma at these locations, or if it is driven by the force of sinking magma elsewhere and these upwellings are merely a side effect. It is likely however that some seafloor spreading is driven by active upwelling and some by passive upwelling.
Issue #133 -
Celebes Sea
The Celebes Sea (or the Sulawesi Sea) of the western Pacific Ocean is bordered on the north by the Sulu Archipelago and Sulu Sea and Mindanao Island of the Philippines, on the east by the Sangi Islands chain, on the south by Sulawesi, and on the west by Borneo. The Sea is in the form of a huge basin, and plunges as deep as 6,200 m. It extends 420 miles (675 km) north-south by 520 miles (837 km) east-west and has a total surface area of 110,000 square miles (280,000 square km). The sea opens southwest through the Makassar Strait into the Java Sea.
Location of Celebes Sea
The Celebes Sea is a piece of an ancient ocean basin that formed 42 million years ago in a setting far from any land mass. By 20 million years ago, crustal movement had pushed the Celebes basin close enough to the Indonesian and Philippine volcanoes to receive volcanic debris. By 10 million years ago the Celebes Sea was inundated with continental debris, including coal, which was shed from a rapidly growing young mountain on Borneo and the basin had docked against Eurasia.
The border between the Celebes and the Sulu Sea is at the Sibutu-Basilan Ridge. Strong ocean currents, deep sea trenches and sea mounts, combined with active volcanic islands, result in complex oceanographic features.
Celebes Sea pirates
The Celebes Sea has somewhat attained an international notoriety for its pirates who prey not only on small time fishermen but also giant container ships. Nowadays, these pirates have high-tech weapons and equipments like radar and GPS navigation devices and ride on high-speed motorboats.
Marine life
The Celebes Sea is home to a wide variety of fish and aquatic creatures. The tropical setting and warm clear waters permit it to harbor about 580 of the world's 793 species of reef-building corals, which grow as some of the most bio-diverse coral reefs in the world, and an impressive array of marine life, including whales and dolphins, sea turtles, manta rays, eagle rays, barracuda, marlin and other reef and pelagic species. Tuna and yellow fin tuna are also abundant.
In addition to high abundance of fish caught in the Celebes Sea, this sea also yields other aquatic products like sea tang.
Celebes Sea on its northern border. Coastal area of Maitum, Sarangani.
Commercial significance
An important transport route for trade and commerce in the region, the Celebes Sea is also a popular site for deep sea diving and luxury ocean cruising.
Issue #134 -
Scheelite
Scheelite is a calcium tungstate mineral with the chemical formula CaWO4. It is an important ore of tungsten. Well-formed crystals are sought by collectors and are occasionally fastened into gemstones when suitably free of flaws. Scheelite has been synthesized via the Czochralski process; the material produced may be used to imitate diamond, as a scintillator, or as a solid state lasing medium.
Scheelite
General
Category: Mineral
Formula: Calcium tungstate - CaWO4
Identification
Colour: Golden yellow, brownish green, brown, pinkish to reddish gray, colourless
Habit: Pseudo-octahedra, massive, columnar, granular
System: Tetragonal
Cleavage: Distinct, two directions
Fracture: Subconchoidal to uneven - brittle
Hardness: 4.5-5
Lustre: Vitreous to adamantine
RI: 1.918–1.937 (DR +0.016)
Pleochroism: Definite dichoric in yellow (yellow to orange-brown)
Streak: White
SG: 5.9–6.1
Fusibility: With difficulty
Solubility: Soluble in acids
Properties
Its crystals are in the tetragonal crystal system, appearing as dipyramidal pseudo-octahedra. Colours include golden yellow, brownish green to dark brown, pinkish to reddish gray, and colourless. Transparency ranges from translucent to transparent and crystal faces are highly lustrous (vitreous to adamantine). Scheelite possesses distinct cleavage and its fracture may be subconchoidal to uneven. Its specific gravity is high at 5.9–6.1 and its hardness is low at 4.5–5. Aside from pseudo-octahedra, scheelite may be columnar, granular, tabular or massive in habit. Twinning is also commonly observed and crystal faces may be striated. Scheelite streaks white and is brittle.
Gems cut from transparent material are fragile yet attractive: Scheelite's refractive index (1.918–1.937 uniaxial positive, with a maximum birefringence of 0.016) and dispersion (0.026) are both moderately high. These factors combine to result in scheelite's high lustre and perceptible "fire", approaching that of diamond. Owing to low hardness, however, cut scheelites are best enjoyed unset as valuable collector's pieces.
Rockhounds treasure scheelite for its fluorescent properties: under shortwave ultraviolet light, the mineral glows a bright sky-blue. The prescence of molybdenum trace impurities occasionally results in a green glow.
Occurrence
Scheelite is associated with wolframite in placer deposits and forms in pegmatites, hydrothermal veins, and areas of contact metamorphism. Other associated minerals include fluorite, muscovite, dolomite and molybdenite. Its type locality is the Bisperg iron mine in Säter, Dalecarlia, Sweden. Officially recognized in 1821, scheelite was named after Swedish chemist Carl Wilhelm Scheele, the discoverer of tungsten.
Crystals exceeding 0.5 kilograms (1 pound) have been found in Brazil: Other notable localities include Australia, Austria, Bolivia, Burma, England, Finland, France, Italy, Japan, Sri Lanka, Switzerland and the United States. The Sichuan Province of China has emerged as a newly important source with many "gemmy" specimens recovered. Fine crystals are also found in Tong Wha, Korea.
Synthetics
Although it is now uncommon as a diamond imitation—much more convincing products, like cubic zirconia and moissanite have long since superseded it—synthetic scheelite is occasionally offered as natural scheelite, and collectors may thus be fooled into paying high prices for them. Gemmologists distinguish natural scheelite from synthetic material mainly by microscopic examination: Natural material is very seldom without internal growth features and inclusions (imperfections), while synthetic material is usually very clean. Distinctly artificial curved striae and clouds of minute gas bubbles may also be obvserved in synthetic scheelite.
The visible absorption spectrum of scheelite, as seen by a hand-held (direct vision) spectroscope, may also be of use: Most natural stones show a number of faint absorption lines in the yellow region of the spectrum (~585 nm) due to praseodymium and neodymium trace impurities. Conversely, synthetic scheelite is often without such a spectrum. Some synthetics may however be doped with neodymium or other rare earths, but the spectrum produced is unlike that of natural stones.
Issue #135 -
Mojave Desert
The Mojave or Mohave Desert occupies a significant portion of Southern California and parts of Utah, Nevada, and Arizona. Named after the Mohave tribe of Native Americans, it occupies over 22,000 mi² (35,000 km²) in a typical Basin and Range topography.
Mojave Desert
The Mojave Desert is bound in part by the Tehachapi together with the San Gabriel and San Bernadino mountain ranges. The mountain boundaries are quite distinct since they are outlined by the two largest faults in California: the San Andreas and the Garlock. Its northern and eastern boundaries are less distinct. One way to determine entry is by observing the presence of Joshua Trees.
Climate
The Mojave Desert receives less than 6 inches (150 mm) of rain a year and is generally between 3,000 and 6,000 feet (1,000 and 2,000 m) in elevation. The Mojave Desert also contains the Mojave National Preserve and the lowest-hottest place in North America: Death Valley, where the temperature normally approaches 120°F (50°C) in late July and early August. Despite its aridity, the Mojave (and particularly the Antelope Valley in its southwest) has long been a center of alfalfa production, fed by irrigation coming from groundwater and (in the 20th century) from the California Aqueduct.
The Mojave, like all deserts in general, is known for its summer heat; however, much less renowned is the Mojave's wintertime cold. Snow, although uncommon, does fall in parts of the Mojave. Amounts range from just a trace to a foot or more of heavy wet snow which can lead to freeway traffic closures and being "snowed in". The coldest wintertime temperature ranges have been below freezing yet above 0°F. That said, many parts of the Mojave typically range from highs of around 95–105°F in the summer to lows of around 20–30°F in the winter.
Wind is also a weather factor. Las Vegas, situated on the desert's east, may not have many winds, but the community of Mojave, situated at its western end, can have wind nearly every day — even winds surpassing fifty miles per hour. Nearby Tehachapi Pass, due to the high likelihood of reliable wind, is home to an extensive electrical windmill turbine "farm" which converts wind, a renewable-clean-resource, into electricity.
The Mojave Desert contains a number of ghost towns, the most significant of these being the silver-mining town of Calico, California and the old railroad depot of Kelso. Some of the other ghost towns are of the more modern variety, created when Route 66 (and the lesser-known US Highway 91) were abandoned in favor of the Interstates. The Mojave Desert is crossed by major highways Interstate 15, Interstate 40, US Highway 395 and US Highway 95.
Among the more popular and unique tourist attractions in the Mojave is the self described World's Largest Thermometer at 135 feet high, reportedly also the highest °F temperature ever recorded in the region, which is located along Interstate 15 in Baker, California. Kelso Dunes is also a popular recreation spot.
The Mojave River is an important source of water in this arid land. A part of the Colorado River also traverses its far eastern portion.
The Mojave Desert is not entirely rural as a few cities do exist there. Las Vegas, Nevada is the Mojave's largest city and metropolitan area. Palmdale is the largest city and metropolitan area on the California side of the desert. Other notable cities include; Henderson, Laughlin, and North Las Vegas in Nevada, and Victorville, Barstow, Lancaster, Ridgecrest, and Needles in California.
Angelenos often refer to its southwestern portions, the Antelope Valley and the Victor Valley, as the High Desert.
Pinnacles National Natural Landmark, Mojave Desert
Slot Canyon, Afton Canyon, Mojave Desert
Coyote Dry Lake, Mojave Desert
Amboy Crater, Mojave Desert
Issue #136 -
Grand Canal of China
The Grand Canal of China, also known as the Jing-Hang Grand Canal is the largest ancient canal or artificial river in the world, the oldest part of the canal dates back to 5th century B.C.
In the year of 604, Emperor Yang Guang of Sui Dynasty left Chang'an (in Xi'an), the capital, and made his rounds in Luoyang. In 605, the emperor gave an order to build two projects: transferring the capital from ChangÂ’an to Luoyang (in Henan) and excavating the Grand Canal linking Beijing and Hangzhou. It took over six years to build the Grand Canal linking all the canals along it and connecting Haihe, Huang He (Yellow River), Huaihe, Yangtze and Qiantangjiang rivers. The Grand Canal starts north in Beijing and ends south in Hangzhou of Zhejiang with a total length of 1,794 kilometers (1,115 miles), passes Beijing, Tianjin, Hebei, Shandong, Jiangsu and Zhejiang.
Grand Canal of China
According to the writings published by Père Gandar, the total length of the canal is 3,630 li, or about 1,200 miles. A rough measurement, taking account only of the main bends of the canal, makes its length 850 miles. After leaving Hangzhou the canal passes round the eastern border of the Lake Tai, surrounding in its course the beautiful city of Suzhou, and then trends in a generally north-westerly direction through the fertile districts of Jiangsu as far as Jingjiang on the Yangtze.
In this, the southern section, the slope is gentle and water is plentiful (from 7 feet at low water to 11 feet, and occasionally 13 feet at high water). Between Suzhou and Jingjiang the canal is often over 100 feet (30 m) wide, and its sides are in many places faced with stone. It is spanned by fine stone bridges, and near its banks are many memorial arches and lofty pagodas.
In the central portion of the canal, that is between Jingjiang and Qingjiangpu, at which latter place it crosses the dry channel which marks the course of the Huang He (Yellow River) before 1852, the current is strong and difficult to ascend in the upward (northern) journey. This part of the canal skirts several lakes and is fed by the Huai He as it issues from the Xingzuo lake. The country lying west of the canal is higher than its bed; while the country east is lower than the canal, The two regions are known respectively as Shanghe (above the river) and Xiahe (below the river). Waste weirs opening on the Xiahe (one of the great rice-producing areas of China) discharge the surplus water in flood seasons.
The northern and considerably the longest section of the canal, extends from the old bed of the Yellow river to Tianjin. It largely utilizes existing rivers and follows their original windings. Between Xingjiangpu and the present course of the Yellow river the canal trends north-northwest, skirting the highlands of Shandong. In this region it passes through a series of lagoons, which in summer form one lake -- Zhouyang. North of that lake on the east bank of the canal, is the city of Ziningzhou. About 25 miles north of that city the highest level of the canal is reached at the town of Nan Wang. Here the river Wen enters the canal from the east, and about 30 miles farther north the Yellow river is reached. On the west side of the canal, at the point where the Yellow river now cuts across it, there is laid down in Chinese maps of the 18th century a dry channel which is described as being followed by the Yellow river before it took the channel it abandoned in 1851-1853.
The passage of the Yellow river to the part of the canal north of this stream is difficult, and can only be effected at certain levels of the river. Frequently the waters of the river are either too low or the current is too strong to permit a passage. Leaving this point the canal passes through a well-wooded and hilly country west of Dongping Zhou and east of Dongchang Fu. At Linjing Zhou it is joined at right angles by the Wei river in the midst of the city. Up to this point, i.e. from Qingjiangbu to Linjing Zhou, a distance of over 300 miles, navigation is difficult and the water-supply often insufficient. The differences of level, 20 to 30 feet, are provided for by barrages over which the boats -- having discharged their cargo -- are hauled by windlasses. Below the junction with the Wei the canal borrows the channel of the river and again becomes easily navigable. Crossing the frontier into Zhili, between De Zhou and Zang Zhou, which it passes to the west, it joins the Beihe at Tianjin, after having received the waters of the Geduo river in the neighbourhood of Qing Jian .
The most ancient part of the canal is the section between the Yangtze and the Huai He. This part is thought, on the strength of a passage in one of the books of Confucius, to have been built c. 486 BC. It was repaired and enlarged in the 3rd century AD. The southern part, between the Yangtze and Hangzhou, was built early in the 7th century AD (initially named as Jiang Nan He). The northern part is stated to have been constructed in the years 1280 to 1283. The northern portion of the canal is now of little use as a means of communication between north and south. It is badly built, neglected and charged with the mud-laden waters of the Yellow River. The central and southern portions of the canal are very largely used.
Issue #137 -
North American craton
The North American craton, like all craton land, was created as continents move about the surface of the Earth, bumping into other continents and drifting away. This process takes millions of years to happen, but the results can be seen today in the rocks of the continents.
The middle of most continents have not been crunched or squished up the way the edges have been. That is because the middle of the continents are made of very strong old rock. This part of the continent is called the stable craton. Indiana is located near the middle of the North American craton.
North American craton
The brown area shows the part of the North American continent that has been stable for over 600 million years. This region is made up of a basement older Precambrian metamorphic and igneous rock that is mostly covered by a relatively thin cover of younger sedimentary rock. Geologists call these long-stable continental cores cratons.
The green area on the illustration shows new continental material that was added relatively recently, within the last 600 million years or so. Continents can grow when two plates collide, welding, or accreting, the two pieces together. Continents also grow when oceanic crust is scraped off oceanic plates as they sink in subduction zones.
The purple area fringing the stable continental core is made up of older Precambrian basement that was deformed during plate collisions that occurred within the last 600 million years. The force of collision produced great folds and faults that sometimes penetrated deep into the continental interior. Where the crust was uplifted, these folds and faults are exposed at the surface, allowing geologists to piece together the ancient history of our continent.
Interior Platform
While much of the stable craton is exposed at the surface north of Indiana as the Canadian Shield, the middle of the craton, located in the United States, is covered with sedimentary rocks of the Interior Platform. The sequence of rocks varies from approximately 3,500 in excess of 20,000 feet in thickness. The cratonic rocks are metamorphic and igneous while the overlying sedimentary rocks are composed mostly of limestones, sandstones, and shales. These sedimentary rocks were deposited from 650 to 290 million years ago.
Tectonic Setting
The metamorphic and igneous rocks of the "basement complex" were created 1.5 to 1.0 billion years ago in a tectonically active setting. It was a setting of great pressure and temperature. The younger sedimentary rocks that were deposited on top of this basement complex were formed in a setting of quiet marine and river waters. Much of this time the craton was covered by a large shallow sea, a so-called "epicratonic sea" (meaning literally "on" the craton). Sometimes land masses or mountain chains rose up on the distant edges of the craton and then eroded down, shedding their sand across the landscape.
Issue #138 -
Newberry Volcano
Newberry Volcano, 7,985 ft (2,434 m) high, is a large shield volcano located 40 miles (60 km) east of the Cascade Range and about 20 miles (30 km) southeast of Bend, Oregon. It is not a typical shield volcano in that, in addition to erupting basaltic lavas, it also has erupted andesitic and even rhyolitic lava.
Newberry Caldera on Newberry Volcano, showing Paulina and East Lakes, and Big Obsidian Flow
Elevation: 7,989 ft (2,435 m) (Paulina Peak)
Location: Oregon, USA
Range: Cascades
Coordinates: 43° 41' 21.09" N 121° 15' 17.47" W
Topo map: USGS Paulina Peak
Type: Shield volcano
Age of rock: < 600,000 years
Last eruption: ~690 AD
Easiest route: road to Paulina Peak
The volcano is 20 miles (30 km) in diameter, has an approximate volume of 80 mile³ (330 km³), and it possesses a large oval-shaped caldera four by five miles in diameter, called the Newberry Caldera. Within the caldera there are two lakes (Paulina Lake and East Lake) many cinder cones, lava flows, and obsidian domes.
A deep gash in the northern caldera wall, dubbed The Fissure, is the end of a 29 mile (47 km) long series of fractures called the Northwest Rift Zone. Approximately 6,100 years ago, fissure basalt flows erupted from the rift and covered part of Newberry's northwest flank.
A great deal of volcanic activity has occurred on Newberry's shield, which itself has one of the largest collections of cinder cones, domes, lava flows, and fissures in the world (local residents call these parasitic vents the "Paulina Mountains", as if they were their own mountain range). Most of the cinder cones are 200 to 400 ft (60 to 120 m) high and have shallow saucer-shaped summit craters. They are typically surrounded by basalt or andesite that erupted from their bases, forming large lava beds. There are also about 20 rhyolite domes or fissures on the eastern, southern, and western flanks. Larger examples include McKay Butte on the west flank (580,000 years old), China Hat (780,000 years old) and East Butte (850,000 years old) on the far eastern base.
During the late Pleistocene and Holocene there have been six eruptive episodes; four rhyolitic (east half of the caldera) and two basaltic (on the flanks).
-- South Obsidian Eruptive Episode: An estimated 12,000 calendar yrs ago, an obsidian dome and related obsidian flow erupted in the southeast part of the caldera.
-- East Rim Eruptive Episode: About 11,200 calendar yrs ago (10,000 C14 yrs B.P.), mafic cinders, scoria, spatter, and lava flows erupted from a fissure on the east rim of the caldera.
-- Interlake Eruptive Episode: A series of rhyolitic eruptions began in the caldera approximately 7,300 calendar yrs ago (6,200 C14 yrs B.P.). They produced a widespread phreatomagmatic pumiceous tephra deposit, obsidian flows, large and small pumice cones, and a pumice ring. This eruptive episode probably lasted for about 200 years.
-- Northwest Rift Eruptive Episode: About 7,000 calendar yrs ago (6,100 C14 yrs B.P.), basaltic andesite lava and cinder cones erupted from extensive fissure vents on the northwest and south flanks of Newberry. Spatter and cinders also erupted from a fissure on the north caldera wall. The lava flows range up to 9 km long and are more voluminous at lower elevations. This eruptive episode probably lasted for less than 50 years.
-- East Lake Eruptive Episode: About 3,500 yrs ago, obsidian flows and associated pumice deposits in the caldera erupted from caldera ring fractures.
-- Big Obsidian Eruptive Episode: About 480 A.D. (1,470 calendar years B.P.), a 3-part sequence of rhyolitic eruptions began, which included an air-fall tephra, ash-flow tephra, and an obsidian flow, from a common vent at the base of the south caldera wall. The initial Plinian eruption 480 A.D. (1,580 C14 yrs B.P.) produced the Newberry pumice fall deposit which blanketed the east flank of the volcano and areas to the east. About 210 yrs later the Paulina Lake ash flow (1,310 C14 yrs B.P.) spread from near the south caldera wall to Paulina Lake. The final phase of the eruption produced the Big Obsidian Flow which covers 2.8 sq km.
Newberry's highest point is located 1,500 ft (450 m) above the southern caldera floor on Paulina Peak, which is just one peak on the caldera rim. The volcano's south flank descends into the basaltic flatlands of central Oregon.
During the Apollo program, parts of the volcano that resemble the Moon's surface were used to train astronauts.
Geology
Newberry Caldera has existed possibly as long as 500,000 years, when the cone of the volcano is thought to have first collapsed. Subsequent caldera-forming collapse events have further deepened the caldera, but volcanic material and lakebed sediments have largely filled in much of this depth.
Issue #139
