~ Mother Earth ~

last SG · 2005-03-28T01:23:34+00:00

Celtic Sea The Celtic Sea (Irish: An Mhuir Cheilteach) is the area of the Atlantic Ocean off the south coast of Ireland. It is bounded to the east by Saint...

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Spitak Earthquake

The Spitak Earthquake was a tremor, measuring 6.8 on the Richter Scale, which took place on December 7, 1988 at 11:41 local time (07:41 UTC) in the Spitak region of Armenia.

Local housing infrastructure (particularly schools and hospitals) performed poorly in the earthquake and this resulted in 25,000 lives lost. It has been estimated that if the earthquake had occurred 5 minutes later, children would have left their schools' unstable buildings. This short time delay could have saved many lives.

The historic Amenaprkitch (All Savior's) Church, ruined in the 1988 Spitak Earthquake.

The entire city of Spitak was destroyed, and there was partial damage to the nearby cities of Leninakan (later renamed to Gyumri) and Kirovakan (later renamed to Vanadzor). The tremor also caused damage to many surrounding villages.

Since most of the hospitals in the area were destroyed, and due to freezing winter temperatures, officials at all levels were not ready for a disaster of this scale and the relief effort was therefore not launched properly. The Armenian government let in foreign aid workers to help with the recovery in the earthquake's aftermath, and this was one of the first cases when rescue and relief workers from other countries were allowed to take part in relief works in the former Soviet Union.

Issue #250

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Great Dividing Range

The Great Dividing Range (a.k.a Eastern Highlands) is Australia's only substantial mountain range. It stretches from the northeastern tip of Queensland, running the entire length of the eastern coastline through New South Wales, then into Victoria and turning west before finally fading into the central plain at the Grampians in western Victoria.

The Great Dividing Range runs around the entire eastern and south-eastern edge of Australia.

Australia's highest mountain, Mount Kosciuszko, and all of mainland Australia's alpine areas are part of this range. The highest areas in southern New South Wales and eastern Victoria are known as the Australian Alps.

In fact Great Dividing Range is a misnomer, as it is not a single range. It does, however, divide the watershed of streams and rivers which flow directly into the Pacific Ocean on the eastern coast of Australia, from streams and rivers of the Murray-Darling Basin which flow inwards, away from the coast into the interior plains. Because of this, the native freshwater fish faunas of the Murray-Darling Basin and East Coast river systems are very different.

In some areas, such as the Blue Mountains, Snowy Mountains, Victorian Alps and the eastern escarpments of the New England region, the highlands form a significant barrier. In other areas the slopes are gentle and in places the range is barely perceptible.

Whilst some of the peaks of the highlands reach respectable heights of a little over 2,000 metres, the age of the range and its erosion mean that the most of the mountains are not outrageously steep, and virtually all peaks can be reached without mountaineering equipment.

Much of the range is in a succession of national parks and other reserves. The lower reaches are used for forestry, an activity that causes much friction with conservationists. It is also the source of virtually all of eastern Australia's water supply, both through runoff caught in dams, and, throughout much of Queensland, through the Great Artesian Basin.

In the early days of European colonization, the Blue Mountains, the part of the range directly west of Sydney, represented an impenetrable barrier to the colonists until 1813, when Gregory Blaxland, William Lawson, and William Wentworth, three graziers, passed the mountains. There are many mountains in the dividing range that include the Snowy Mountains and the Blue Mountains.

Issue #251

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Haze

Haze is an atmospheric phenomenon where dust, smoke and other pollutant particles obscure the normal clarity of the sky. It occurs when dust and smoke particles accumulate in relatively dry air. When weather conditions block the dispersal of smoke and other pollutants they concentrate and form a usually low-hanging shroud that impairs visibility and may become a respiratory health threat. Dense haze caused by industrial pollution is also known as smog.

Moon over red and blue haze

Sources for haze particles include farming (ploughing in dry weather), traffic, industry, forest fires and peat field fire.

Seen from far (e.g. approaching airplane), haze is brownish, while mist is more blueish-grey. While haze is formed in relatively dryish air, in more humid air mist is formed, and the haze particles can even act as condensation nucleii for the mist droplets.

Haze in Southeast Asia

Haze is a regular problem in Southeast Asia caused by land and forest fires in Indonesia, especially Sumatra and Kalimantan. Those fires mainly affect Brunei, Indonesia, Philippines Malaysia, Singapore and Thailand. The economic losses of the fires in 1997 have been estimated at US$9.3 billion. This includes damages in agriculture production, destruction of forest lands, health, transportation, tourism, and other economic endeavours. Not included are social, environmental, and psychological problems and long term health effects. The latest bout of haze to occur in Malaysia and the Malacca Straits was in August 2005.

Severe haze affecting Ampang, Kuala Lumpur, Malaysia in August 2005

As a reaction, Association of Southeast Asian Nations (ASEAN) signed Agreement on Transboundary Haze Pollution, formed a Regional Haze Action Plan (RHAP) and established a co-ordination and support unit (CSU). As part of this Action Plan and with the help of Canada, a monitoring and warning system for forest/vegetation fires was developed and implemented called Fire Danger Rating System (FDRS). Since September 2003 daily ratings have been issued by the Malaysian Meteorological Service (MMS).

Pollution index

The severity of haze is often measured using automated laser instruments such as Nephelometers, as haze is associated with visibility and traffic control in ports. Haze however can also be an indication of poor air quality though this is often better reflected using accurate purpose built air indexes such as the American Air Quality Index or the Malaysian API (Air Pollution Index)

In hazy conditions, it is likely that the index will report the suspended particulate level. The disclosure of the responsible pollutant is mandated in some jurisdictions.

The American AQI is divided into six color coded categories, similar to homeland security. Technically AQI runs only from 0 to 500. The 301 to 500 range is categorised as hazardous and colored maroon.

The Malaysian APIs most hazardous category is above 500. Above 500, a state of emergency is declared in the reporting area. Usually, this means that non essential government services are suspended, and all ports in the affected area closed. There may also be a prohibition on private sector commercial and industrial activities in the reporting area excluding the food sector. So far, the state of emergency ruling due to a hazardous API level applied to the Malaysian towns of Port Klang, Kuala Selangor (2005) and Sarawak state (1997).

Issue #252

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Dry Tortugas National Park

Dry Tortugas National Park is a United States National Park, located in the Dry Tortugas islands of the Florida Keys. The park covers 101 mi² (262 km²).

Location of Dry Tortugas National Park

It is famous for abundant sea life, colorful coral reefs and legends of shipwrecks and sunken treasures. The park's centerpiece is Fort Jefferson, a massive but unfinished coastal fortress that was rendered obsolete by the invention of the rifled cannon. The fort was eventually converted into a prison for Union Army deserters and the accomplices implicated in President Abraham Lincoln's assassination. The U.S. Army abandoned the fortress in 1874 and a nearby sooty tern rookery was a favored hunting ground for egg collectors until a wildlife refuge was established in 1908. In 1935 President Franklin Roosevelt designated it Fort Jefferson National Monument, and in 1992 the Dry Tortugas was declared a national park. The islands do not exhibit any standing fresh water or even seasonal streams, hence their name. Owing to the potential difficulties of survival in such conditions one of these islands were used as the location for the filming of a military survival film used to train aircraft personnel.

Fort Jefferson

The park is roughly 70 miles or 110 kilometers by boat west of Key West, and plays host to almost 80,000 visitors each year. Activities include snorkeling, picnicking, scuba diving, saltwater fishing and birdwatching.

The most popular bird watching event is the sooty tern gathering, the nesting season on Bush Key between February and September involving an estimated 100,000 terns. Bush Key remains closed to visitors during the nesting season, but bird watchers with binoculars or telephoto lenses can watch the spectacle from Fort Jefferson. Other bird species in the park include noddies, brown pelicans, frigate birds, masked boobies, roseate terns, brown boobies and double-crested cormorants.

Underwater artifact with sea life

Issue #253

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Jared Diamond

Jared Mason Diamond (born September 10, 1937) is an American author, evolutionary biologist, physiologist, and biogeographer. He is best known for the Pulitzer Prize-winning book, Guns, Germs, and Steel (1997), which asserts that the main international issues of our time are legacies of processes that began during the early-modern period, in which civilizations that had experienced an extensive amount of "human development" began to intrude upon simpler civilizations around the world. Diamond's quest is to explain why such advanced civilzations developed only in Eurasia, and to do so in ways that do not appeal to ethnocentric myths, but do away with them. Most significantly, although it identifies the main processes and factors of civilizational development that were present in Eurasia, but not elsewhere, it does so by tracing commonalities between Eurasian civilizations, leaving the question open of why Europe came to supersede other Eurasian civilizations after 1800.

Jared Mason Diamond

Diamond was born in Boston to a physician father and a teacher/musician/linguist mother. After attending The Roxbury Latin School, he earned a BA degree from Harvard in 1958 and his PhD in physiology and membrane biophysics from Cambridge University in 1961. During 1962-1966, he returned to Harvard as a junior Fellow. He became professor of physiology at UCLA Medical School in 1966. While in his twenties, he also developed a second parallel career in the ecology and evolution of New Guinea birds, and he has led numerous trips to explore New Guinea and nearby islands. In his fifties, Diamond gradually developed a third career in environmental history, becoming professor of geography and of environmental health sciences at UCLA, his current position.

Diamond is renowned as the author of a number of popular science works that combine anthropology, biology, linguistics, genetics, and history. While Diamond became a staunch opponent of the use of genetic and racial arguments to account for the differences in technological sophistication, his early work included a paper entitled "Ethnic differences: Variation in human testis size", in which he investigated correlations between possible genetic and racial variations in testicular size and hormone levels and argued that testicular size and hormone levels were highest among African races and lowest in East Asian, with Caucasian populations falling between the two.

In his most recent book, Collapse: How Societies Choose to Fail or Succeed (2004), Diamond examines what caused some of the great civilizations of the past to collapse into ruin and considers what contemporary society can learn from their fates.

Diamond speaks a dozen languages, and his books rely on fields as diverse as molecular biology and archaeology, as well as obscure knowledge about everything from typewriter design to feudal Japan. Because of his broad expertise and the large number of articles credited to him, it has been suggested jokingly by Mark Ridley that "Jared Diamond" is not a single person, but instead "is really a committee".

Diamond is on the editorial board of Skeptic Magazine, a publication of The Skeptics Society.

Diamond is a member of the American Philosophical Society, the American Academy of Arts and Sciences, and the National Academy of Sciences.

Issue #254

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Ruin

Ruins are the remains of a piece of man-made architecture. The term is used to describe a structure that was at one time whole but has, with the intervention of weathering and lack of maintenance, become wrecked by time. There are basic types of ruins that can be found in the world. Historical ruins, like those found at Rome and Athens, have been unearthed through the work of archaeologists. Modern ruins, such as abandoned buildings in large metropolitan areas, are discovered by urban exploration.

Rocky landscape with ruins, by Nicolaes Berchem, ca. 1650 (Alte Pinakotek, Munich)

In Christian iconography, the Nativity of Christ has often been depicted in a setting of grand ruins, symbolising the new Temple (the body of Christ) that rises on the site of the old.

Popular adventure films, such as the Indiana Jones trilogy or the Mummy films, rely on ancient relics and artifacts found in ruins. The idea of the ruin has become prominent in popular culture as a device with which to add suspense and in many cases horror.

Architectural follies were sometimes built as intentional ruins.

Burg Are

In the Third Reich, Adolf Hitler and Albert Speer designed buildings calculated to have a high "ruin value" for posterity. These buildings were never built, but perhaps ironically some of the most recent and understated modern ruins (ruined through passage of time rather than intentional destruction) are the uncompleted autobahn motorways built by the Nazis that litter the German countryside.

Issue #255

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Firth of Clyde

The Firth of Clyde is the estuary of the River Clyde, from its upper tidal limit in Glasgow city centre to the outer firth in Argyll and Ayrshire, Scotland.

The Holy Loch seen across the Firth of Clyde with Dunoon on the left.

Geography

The firth encompasses many islands and peninsulas and has twelve ferry routes connecting them to the mainland and each other. The majority of these services are run by Caledonian MacBrayne and many of the routes are lifeline services for communities living in remote areas. A number of sea lochs adjoin the firth.

History

In Victorian times with the advent of tourism the area became popular with well heeled Glaswegians who travelled 'doon the watter' on pleasure steamers to holiday in the picturesque seaside towns that line the firth. Many of these towns such as Largs, Dunoon and Rothesay flourished during this boom period and became fully fledged resorts with well appointed hotels and attractions.

In 1942 the World's first deep water test of a submarine oil pipeline was conducted on a pipeline laid across the Firth of Clyde in Operation Pluto.

In more recent times the firth has sadly had much of its natural beauty diminished by a succesion of industrial and military developments along the shoreline.

Marine wildlife

Common & Grey Seals abound in the firth.

Harbour Porpoises are also common and while Dolphins are much less so they have been spotted in the upper reaches of the firth in the summer of 2005. Whales do not favour the Clyde and although there have been instances of larger whales beaching themselves or becoming stranded in the upper firth, only smaller Pilot or Minke Whales seem to visit with any kind of regularity.

In 2005 the firth was listed as having the 2nd highest incidence of basking shark sightings in Scotland (after the Hebridean Sea). In particular these huge sharks seem to favour the warm, shallow waters surrounding Pladda.

Although at one time heavily fished, the only animals remaining in Clyde waters today that are of any commercial interest to fisherman are Prawns, Lobster and a little Herring.

There is a Marine Biological Station run by the Universities of Glasgow and London on Great Cumbrae.

Shipping in the Firth

The Firth of Clyde like the River Clyde has historically been an important centre of shipbuilding. There have been shipyards at Renfrew, Greenock, Port Glasgow and Troon and a highly regarded boatyard at Fairlie.

Ships are still seen in the firth today many visiting the deep sea cargo terminal, Clydeport.

Issue #256

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Ice shelf

An ice shelf is a thick, floating platform of ice that forms where a glacier or ice sheet flows down to a coastline and onto the ocean surface, typically in Antarctica or Greenland. The boundary between floating ice shelf and the grounded (resting on bedrock) ice that feeds it is called the grounding line. When the grounding line retreats inland, water is added to the ocean and sea level rises.

Ross Ice Shelf

In contrast, sea ice is formed on water, is much thinner, and forms throughout the Arctic Ocean. It also is found in the Southern Ocean around the continent of Antarctica.

Ice shelves flow by gravity-driven horizontal spreading on the ocean surface. That flow continually moves ice from the grounding line to seaward front of the shelf. The primary mechanism of mass loss from ice shelves is iceberg calving, in which a chunk of ice breaks off from the seaward front of the shelf. Typically, a shelf front will extend forward for years or decades between major calving events. Snow accumulation on the upper surface and melting from the lower surface are also important to the mass balance of an ice shelf.

The thickness of modern-day ice shelves ranges from about 100 to 1000 meters. The density contrast between solid ice and liquid water means that only about 1/9 of the floating ice is above the ocean surface. The world's largest ice shelves are the Ross Ice Shelf and the Filchner-Ronne Ice Shelf in Antarctica.

Antarctic ice shelves

The Antarctic continent is mostly surrounded by ice formations. The coast composition is:

Coastal types around Antarctica (from Drewry, 1983)
Type -- Frequency
Ice shelf (floating ice front) -- 44%
Ice walls (resting on ground) -- 38%
Ice stream/outlet glacier (ice front or ice wall) -- 13%
Rock -- 5%
Total -- 100%

Recently, glaciologists have observed unexpected ice-shelf events, such as complete disintegration of some small ice shelves. For example, two sections of Antarctica's Larsen Ice Shelf broke apart into hundreds of unusually small fragments (100's of meters wide or less) in 1995 and 2002. The breakup events are linked to climate change in the region, although there is not complete agreement about the most important causative process. The leading ideas involve enhanced ice fracturing due to surface meltwater and enhanced bottom melting due to warmer ocean water circulating under the floating ice.

The cold, fresh water produced by melting underneath the Ross and Flichner-Ronne ice shelves is a component of Antarctic Bottom Water.

Issue #257

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Socotra

Socotra or Soqotra is a small archipelago of four islands and islets in the Indian Ocean off the Horn of Africa some 350 km south of the Republic of Yemen, which administers Socotra for the Banu Afrar Mahra Sultanate of Qishn and Socotra.

Map of the Socotra archipelago

Geography and climate

The archipelago consists of the mountainous main island of Socotra (3,625 km² ) and three smaller islands known collectively as "the Brothers", Abd Al Kuri, Samha, Darsa, plus other uninhabitable rock outcrops. Abd Al Kuri and Samha have a population of a few hundred people between them; Darsa is uninhabited. The principal city is Hadiboh (estimated population in 2004, 43,000) The inhabitants of Socotra raise cattle and goats.

The climate is generally tropical desert, with rainfall being light, seasonal (winter) and more abundant at the higher ground in the interior than along the coastal lowlands.

Socotra has three geographical terrains: the narrow coastal plains, a limestone plateau permeated with karstic caves, and the Haghier mountains.

Satellite image of Socotra

Socotra is one of the most isolated bits of land on earth of continental landmass origin (i.e., not of volcanic origin). The island probably detached from Africa as a fault block during the Middle Pliocene (ca 6 mya), in the same set of rifting events that have opened the Gulf of Aden to its northwest. The long geological isolation of the archipelago and its fierce heat and drought have combined to create a unique and spectacular endemic flora that would be highly vulnerable to change; surveys have revealed that more than a third of the 800 or so plant species of Socotra are found nowhere else. Botanists rank the flora of Socotra among the ten most endangered island flora in the world. The archipelago is a site of global importance for biodiversity conservation and a possible center for ecotourism. Even the Modern South Arabian Semitic language, Soqotri, is spoken only there, although it is related to other South Arabian languages on the Arabian mainland such as Mehri language.

One of the most striking of Socotra's plants is the dragon's blood tree (Dracaena cinnabari), which is a very strange-looking, umbrella-shaped tree. Its red sap was the dragon's blood of the ancients, sought after as a medicine and a dye.

As with many isolated island systems, bats are the only mammals native to Socotra. In contrast, the marine biodiversity around Socotra is rich, characterized by a unique mixture of species that have originated in farflung biogeographic regions: the western Indian Ocean, the Red Sea, Arabia, East Africa and the wider Indo-Pacific.

The monsoonal climate is strong: from June to September the island has traditionally been inaccessible, because of exceedingly strong monsoon winds and high seas. In July 1999 a new airport opened Socotra to the outside year round. Most Socotris still live without electricity, running water or a paved road. At the end of the 1990s a United Nations Development Programme was launched with the aim of providing a close survey of the island of Socotra. The semiarid island is mountainous with a narrow coastal plain. Interior mountains rise to 5,000 feet (1,525 meters). The chief products of the island are dates, ghee, tobacco, and fish.

History

Socotra appears as Dioskouridou ("of the Dioscurides") in the 1st century Periplus of the Erythraean Sea, a navigation aid. In the notes to his translation of the Periplus, G.W.B. Huntingford remarks that the name Socotra is not Greek in origin, but from the Sanskrit dvipa sukhadhara ("island of bliss"). A local tradition held that the inhabitants were converted to Christianity by Thomas in AD 52, and in the 10th century the Arab geographer Abu Mohammed Al-Hassan Al-Hamdani stated that in his time most of the inhabitants were Christians.

The explorer Tristão da Cunha put ashore in the early 16th century and considered Socotra conquered for Portugal, at which time Christianity had disappeared from the island except for stone crosses at which Alvares said people worshipped. However, during a visit of the island in 1542, Francis Xavier found a group of people claiming to be descended from the converts made by St. Thomas.

The islands passed under the control of the Mahra sultans in 1511, but eventually became a British protectorate in 1886, for whom it was an important strategic stop-over. With the independence of Yemen, the islands arrived at their current arrangement.

Issue #258

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Katse Dam

The Katse Dam, part of the Lesotho Highlands Water Project, is a concrete arch dam in Lesotho.

Katse Dam

The dam was completed in 1996 and filled by 1997, causing induced seismicity and evacuation of a handful of local residents.

Water from the dam first travels through a 45 km, 4 m diameter tunnel, exiting at a hydroelectric station near Muela. The dam's high elevation allows a gravity flow delivery system to South Africa, in addition to hydroelectric power for Lesotho, and was a prime reason behind the choice of site.

Water delivery officially began on 22 January 1998. The dam currently supplies about 30 m3/s of water to South Africa, which pays Lesotho $5 million per year, plus a variable royalty based on calculated water usage benefits.

Dam features

- Height - 185 m
- Crest length - 710 m
- Design - double arch, concrete
- Concrete - 2,320,000 cubic metres
- 1993 meters above sea level (highest dam in Africa)

Issue #259

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Okefenokee Swamp

The Okefenokee Swamp is a shallow, 400,000 acre (1,600 km²), peat-filled marsh straddling the Georgia-Florida border, in the United States. It is the largest freshwater swamp in North America. It is believed to have been a prehistoric salt marsh. The name means "trembling earth" in a Native American language. It is bordered by the Trail Ridge west of the marsh and the Saint Marys River to the east. The swamp forms the head waters of the Suwannee River which has its origination at the Suwannee River sill on the north side of the swamp. Most of the Georgia portion of the swamp is included in the Okefenokee National Wildlife Refuge.

Canal Diggers Trail in Okefenokee Swamp

There are four public entrances or landings to the swamp:
- Suwannee Canal Recreation Area at Folkston, GA,
- Stephen C. Foster State Park at Fargo, GA,
- Kingfishers Landing at Race Pond, GA,
- Okefenokee Swamp Park at Waycross, GA.

In addition, Florida State Road 2 passes through the Florida portion between the Georgia cities of Council and Moniac.

It is also the home of the comic strip character Pogo.

Issue #260

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Cheddar Gorge

Cheddar Gorge is the largest gorge in the United Kingdom, near the village of Cheddar in the Mendip Hills in Somerset, England. The gorge is the site of the Cheddar Caves, where Britain's oldest complete human skeleton at 9,000 years old, Cheddar Man, was found. Older remains from the Upper Late Palaeolithic era (12,000 - 13,000 years ago) have been found.

Cheddar Gorge is the largest gorge in the United Kingdom.

Jacob's Ladder is a public path of 274 steps, built up the side of the gorge. The gorge is a Site of Special Scientific Interest and a tourist site.

The rocks of the gorge are Carboniferous Limestone on top of Old Red Sandstone. The river at the bottom of the gorge is the Cheddar Yeo, rising in the gorge in Gough's Cave. The maximum depth of the gorge is 113 m (370 ft).

The gorge, which has no river for most of its length, has near-vertical sides and shows characteristics of a river-formed valley. The lack of water is expected since limestone is permeable (it is pervious - allows water through its cracks, but is non-porous - doesn't have any holes.). The gorge was formed in the ice age when any water in the limestone froze, making the rock temporarily impermeable. Torrents of melt water gradually eroded the rock away to form the gorge. After the ice age the limestone thawed and became permeable again so that any water on the surface seeped into the rock, leaving behind a dry valley.

In a 2005 poll of Radio Times readers, Cheddar Gorge was named as the second greatest natural wonder in Britain (surpassed only by Dan yr Ogof caves).

Issue #261

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Dingle Peninsula

The Dingle Peninsula (Irish: Corca Dhuibhne) is located in County Kerry and is the most westerly point of the Republic of Ireland. The peninsula is named after the town of Dingle and is the location of numerous prehistoric and early medieval remains, for example the Gallarus Oratory in the very west of the peninsula near the village of Baile an Fheirtéaraigh. The peninsula exists because of the band of granite rock that forms the Sliabh Mish mountain range. Ireland's second highest mountain, Mount Brandon, at 953 m (3,127 ft) forms part of a beautiful high ridge with stunning views over the peninsula and North Kerry.

Dingle Peninsula as viewed from Banna Strand

The Conor Pass going from Dingle on the southern end of the peninsula towards Brandon Bay and Castlegregory in the North is the highest mountain pass in Ireland, a tight precarious road weaving its way around the sharp cliff faces and past the high corrie lakes.

The Blasket Islands lie off the west coast. They are famous for the literary and linguistic heritage of the former inhabitants. However, these remote islands have been uninhabited since the 1950's following a government rehousing plan.

Brandon Bay, Dingle Peninsula

The western end of the peninsula is a Gaeltacht area that has produced a number of regionally notable authors and poets, like Ó Siochfhradha, and Peig Sayers, among others. This is the most western part of Ireland, and the village of Dún Chaoin is often jokingly referred to as "the next parish to America".

Issue #262

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Breccia

Breccia, derived from the Latin word for "broken," is typically a sedimentary rock composed of angular fragments in a matrix that may be of a similar or a different material. A conglomerate by contrast is a sedimentary rock composed of rounded fragments or clasts of pre-existing rocks. Both breccias and conglomerates are composed of fragments averaging greater than 2 mm in size. The angular shape of the fragments indicate that the material has not been transported far from its source. Breccias indicate accumulation in a juvenile stream channel or accumulations due to gravity erosion. Talus slopes may become buried and the talus cemented in a similar manner.

Basalt breccia, green groundmass is composed of epidote.

Fault breccias result from the grinding action of two fault blocks as they slide past each other. Subsequent cementation of these broken fragments may occur by means of mineral matter introduced by groundwater.

Volcanic breccias result from the cementation or welding (when the material is glass) of fragments that have been broken by volcanic action. Sometimes the surface of a lava flow will harden while the interior will remain liquid; the fracturing of the surface layer and its subsequent cementation by uncooled lava produces flow breccia.

The intrusion of plutonic rocks will often shatter the invaded country rock, producing a shatter breccia. In the case of plutonic rocks partly cooled and subsequently broken by further invasions of magma, intrusive breccias are formed. Explosive release of volatiles can form masses or pipe like breccias above an intrusion . These shatter breccias or breccia pipes may be mineralized by later hydrothermal fluids forming metal rich sulfide ores.

Impact breccias are thought to be diagnostic of an impact event such as an asteroid or comet striking the earth, and are usually found at impact craters.

Ornamental uses of breccia

The striking visual appearance of breccias has for millennia made them a popular sculptural and architectural material. Breccia was used on a limited scale by the ancient Egyptians - one of the best-known examples is the statue of the goddess Tawaret in the British Museum). It was regarded by the Romans as an especially precious stone and was often used in high-profile public buildings. Many types of marble are brecciated, such as Breccia Oniciata or Breche Nouvelle.

Breccia statue of the ancient Egyptian goddess Tawaret

It is most often used as an ornamental or facing material in walls and columns. A particularly striking example can be seen in the Pantheon in Rome, which features two gigantic columns of pavonazzetto, a breccia coming from Phrygia (in modern Turkey). Pavonazzetto obtains its name from its extremely colourful appearance, which is reminiscent of a peacock's feathers (pavone is "peacock" in Italian).

Issue #263

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Jan Mayen

Jan Mayen Island, a part of the Kingdom of Norway, is a 373 km² arctic volcanic island partly covered by glaciers and divided into two parts by a narrow isthmus. It lies 600 km north of Iceland, 500 km east of Greenland and 1,000 km west of the Norwegian mainland at 71° N 8° W. The island is mountainous, the highest summit being Beerenberg in the north (2,277 m).

Jan Mayen

Economy

Jan Mayen Island has no exploitable natural resources. Economic activity is limited to providing services for employees of Norway's radio and meteorological stations located on the island. It has one unpaved airstrip about 1,585 meters long, and its 124.1 kilometers of coast include no ports or harbors, only offshore anchorages. Commercial whaling took place between 1633 and 1640 by the Dutch but ended when the Dutch team of seven died of scurvy and the Greenland right whale nearly became extinct. A dispute between Norway and Denmark regarding the fishing exclusion zone between Jan Mayen and Greenland was settled in 1988 granting Denmark with the greater area of sovereignty.

Jan Mayen is an integrated geographical body of Norway. Since 1995 it has been administered by the county governor (fylkesmann) of Nordland; however, some authority has been delegated to a station commander of the Norwegian Logistics Organisation-CIS, a branch of the armed forces.

Orthographic projection centred on Jan Mayen Island

History

Henry Hudson discovered the island in 1607 and called it Hudson's Tutches or Touches. Thereafter it was observed several times by navigators who successively claimed its discovery and renamed it. Thus, in 1611 or the following year whalers from Hull named it Trinity Island; in 1612 Jean Vrolicq, a French whaler, called it Île de Richelieu; and in 1614 English captain John Clarke named it Isabella, but it didn't stick and later in the same year Joris Carolus named one of its promontories Jan Meys Hoel, after the captain of one of his ships. The present name of the island is derived from this, the claim of its 1611 discovery by a Dutch navigator, Jan Mayen, being unsupportable.

The island is inhabited by personnel operating a Long Range Navigation (Loran-C) base with a staff of 14 and a weather services station with a staff of four. The staff members of both stations live in Olonkinbyen (English: Olonkin City), as the living quarters by the Loran-C base are called. The Loran-C system however is being shut down 31st Dec 2005. The island has no indigenous inhabitants, but is assigned the ISO 3166-1 country code SJ, the Internet country code top-level domain (ccTLD) .no (.sj is allocated but not used) and data code JN. Its amateur radio call sign prefix is JX.

Issue #264

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Grassland

Grassland is one of several types of terrestrial biomes, where grasses form the predominant vegetation, usually mixed with herbs and sometimes with shrubs, but usually without trees. Grasslands dotted with trees are called savanna.

An Inner Mongolian Grassland.

Grasslands usually get 25-75 cm (10-30 inches) of rainfall annually. Fires, natural and human-caused, are important in the maintenance of many grasslands.

Grasslands may occur naturally or as the result of human activity. Grasslands created and maintained by human activity are called anthropogenic grasslands. Hunting peoples around the world often set regular fires to maintain and extend grasslands, and prevent fire-intolerant trees and shrubs from taking hold. The tallgrass prairies in the American Midwest may have been extended eastward into Illinois, Indiana, and Ohio by human agency. Other anthropogenic grasslands include pasture, where forest or shrublands were cleared to create land for intensive grazing.

Tropical and subtropical grasslands are classified with tropical and subtropical savannas and shrublands as the tropical and subtropical grasslands, savannas, and shrublands biome. Notable tropical and subtropical grasslands include the Llanos grasslands of northern South America.

Temperate grasslands are mid-latitude grasslands, including the Prairie of North America, the Pampa of Argentina, calcerous downland, and the steppes of Eurasia. They are classified with temperate savannas and shrublands as the temperate grasslands, savannas, and shrublands biome.

Flooded grasslands are grasslands that are flooded seasonally or year-round, like the Everglades of Florida or the Pantanal of Bolivia and Paraguay. They are classified with flooded savannas as the flooded grasslands and savannas biome, which occurs mostly in the tropics and subtropics.

Montane grasslands are high-altitude grasslands located on high mountain ranges around the world, like the Páramo of the Andes Mountains. They are part of the montane grasslands and shrublands biome.

Xeric grasslands or desert grasslands are sparse grasslands located in deserts and xeric shrublands ecoregions.

Issue #265

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Grand Prismatic Spring

The Grand Prismatic Spring in Yellowstone National Park is the largest hot spring in the United States, and the third largest in the world, next to those in New Zealand.

Grand Prismatic Spring

History

There is no doubt that many of the Native American people were aware of the Grand Prismatic Spring long before Europeans first saw it but the first records of the Spring are from early explorers and surveyors.

In 1839, a group of fur trappers from the American Fur Company crossed the Middle Geyser Basin and made note of a 300-foot (91 meter) diameter "boiling lake", most likely Grand Prismatic Spring.

In 1870, the Washburn Party, led by General Henry D. Washburn, visited the Spring, noting a 50-foot (15 meter) geyser (later named Excelsior) nearby.

Color

The vivid colors in the spring are the result of pigmented bacteria in the microbial mats that grow around the edges creating the greens, yellows, oranges, and reds and refracted skylight creating the bright blue in the center of the pool. The amount of color in the microbial mats depends upon the ratio of chlorophyll to carotenoids. In the summer, the mats tend to be orange and red whereas in the winter, the mat are usually dark green.

Grand Prismatic Spring from the air showing the coloration that gives the spring its name.

Issue #266

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Rift

In geology, a rift is a place where the Earth's crust and lithosphere are being pulled apart. Typical features are a central linear downdropped fault segment, called a graben, with parallel normal faulting and rift-flank uplifts on either side. The axis of the rift area commonly contains volcanic rocks and active volcanism is a part of many but not all active rift systems.

Rifts are distinct from Mid-ocean ridges, where new oceanic crust and lithosphere is created by seafloor spreading. In rifts, no crust or lithosphere is produced. If rifting continues, eventually a mid-ocean ridge may form, marking a divergent boundary between two tectonic plates. Failed rifts are ancient to modern features where continental rifting began, but then failed to continue. Typically the transition from rifting to spreading develops as three converging rifts over a hotspot. Two of these evolve to the point of seafloor spreading, while the third ultimately fails, becoming an aulacogen.

Examples of rifts include:

- Great Rift Valley in Africa
- Red Sea
- Lake Baikal, the bottom of the lake is the deepest continental rift on the earth.
- throughout the Basin and Range Province in North America
- the Rio Grande Rift in the southwestern US
- the rift in the middle of the Gulf of Corinth in Greece
- The Reelfoot Rift, an ancient buried failed rift underlying the New Madrid Seismic Zone in the Mississippi embayment
- the Taupo Volcanic Zone in the north east North Island of New Zealand
the Oslo graben in Norway.

Issue #267

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Java Sea

The Java Sea (Jawa Sea) is a large (310,000 km²), shallow sea in the southern Pacific Ocean. It was formed toward the end of the last ice age when two large river systems were drowned out. It lies in the midst of the Indonesian islands of Borneo to the north, Java to the south; Sumatra to the west, and Sulawesi (Celebes) to the east. To the northwest, the Karimata Strait links it to the South China Sea.

Location of the Java Sea

Fishing is an important economic activity in the Java Sea. There are over 3,000 species of marine life in the area.

The area around the Java Sea is a popular tourist destination. Scuba diving offers a chance to explore and photograph underwater caverns, wrecks, coral, sponges, and other marine life. A number of national parks exist in the area. Near Jakarta, in the Thousand Islands, is Ujung Kulon National Park. Karimun Java is a national park comprising twenty-seven islands. Menjagan Island, near Bali, is in a secluded national park.

The Java Sea was the site of one of the costliest (to the Allies) naval battles of World War II, in February and March of 1942. The naval forces of the Netherlands, Britain, Australia, and the U.S. were nearly completely destroyed trying to defend Java from Japanese attack.

Issue #268

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