Altiplano

The Altiplano is a high plateau located in the central ANDES region of South America at an altitude of about 13,123 ft (4,000 m). It reaches into parts of PERU, BOLIVIA, CHILE, and ARGENTINA. On the west, it bounds the Cordillera Occidental and borders the Cordillera Oriental on the east. It is surrounded by volcanoes reaching altitudes of 19,685 ft (6,000 m), whose activities have caused landfalls that are responsible for the reshaping of this large plateau. The Altiplano has an area of 105,633 square mi (170,000 square km) that is volcanic in origin.

Lake TITICACA is the lowest point of the Altiplano, and occupies its northern basin. It is located at an altitude of 12,500 ft (3,810 m). It has an area of 5,632 square mi (14,587 square km) and reaches depths of 1,214 ft (370 m), making it the highest navigable body of water on earth. The large volume of water makes it possible for the lake to retain a stable 50 degrees F (10 degrees C) temperature. The lake plays an important part in affecting the surrounding climate. The southern basin of the Altiplano is occupied by shallow salt lakes and flats. Lake Titicaca drains into Lake Poopo through the Desaguadero River. Lake Poopo, which is a shallow saltwater lake whose depth rarely reaches more than 13 ft (4 m), is dependent on the flow of water from Lake Titicaca and seasonal rainfall. One of the largest salt flats in the Altiplano is the Uyuni Saltpan. It is all that remains of an ancient lake that covered an area of 5,592 square mi (14,483 square km). Today, this saltpan is filled with salt, which can be as deep as 16 ft (5 m).

The Altiplano’s climate is characterized by a long dry season, lasting from April to November, and a short wet season. The wet season is from November to March, when 95 percent of the rainfall occurs. The amount of rain decreases from northeast to southwest. This is possible since a rain shadow effect is created that allows the northeast to receive more water. The Cordillera Oriental, for example, receives about 51 in (130 cm) of water annually, while the southern Antiplano receives only 6 in (15 cm). The atmosphere here is more transparent to radiation because of the greenhouse effect. This causes an increase in nighttime heat loss, which is noticeably greater than the rate at sea level. The ultraviolet radiation is 20 percent greater in the Altiplano than the radiation at sea level.

The highest temperatures during the summer are measured in late November, reaching 68 degrees F (20 degrees C) during daytime and falling to near 5 degrees F (-15 degrees C) at night. During the winter, June to August, mean temperatures reach as high as 55 degrees F (13 degrees C) and fall to 12 degrees F (-11 degrees C) at night. Strong winds are common in the Altiplano, reaching 62 mi per hour (97 km per hour). They are present nearly every day and are usually stronger in the afternoon.

The Altiplano ecosystem has a dry STEPPE climate, predominated by grasses. The lack of oxygen in the high altitudes of the Altiplano allows only a few plants and animals to survive. Some of the animals living in the region are condors, flamingos, different species of cameloids (e.g., American camels), llamas, alpacas, and many bird species. The Altiplano is also home to the quenoa tree, which grows at an elevation of over 11,500 ft (3,500 m).

The Altiplano has been home to the Inca peoples. Today, some of its areas are populated by Aymara natives. Since the Inca’s time, the plateau has seen much mining: Gold and silver are two of the metals sought by miners and mining companies. Other natural resources include tin, natural gas, petroleum, zinc, tungsten, antimony, silver, iron, and lead. Mining has been the source of pollution to the air, water, and soil in the Altiplano.

Altai Mountains

THE ALTAI MOUNTAINS are a system of remote mountains in central Asia that cover an area of 326,256 square mi (845,000 square km) bounding RUSSIA, KAZAKHSTAN, MONGOLIA, and CHINA. This system is a natural marvel that has been largely untouched by large industries and has a very sparse population. Its name is derived from the Mongolian word altan, which means “golden.” This region is home to many species of wildlife and plants and is made up of various landscapes. Most of the population in this region relies on farming and tourism.

The mountains stretch for 1,242 mi (2,000 km) from northwest to southeast, reaching a height of about 14,783 ft (4,506 m) at Belukha. Many rivers can be found in the Altai Mountains and most of them are fed by glaciers. Some of the largest rivers are Katun, Biya, and Chuya. The glaciers cover an area of about 900 square mi (2,330 square km). Together with intensive river erosions, they have contributed significantly to the creation of the ruggedness of the region, where high waterfalls, steppes, and thousands of lakes can also be found. The deepest lake in the Altai Mountains, Teletskoe, is 1,066 ft (325 m) deep. The Altai Mountains are the source of the Ob and Irtysh Rivers, two of the major rivers in Asia. The region is rich in many natural resources like iron, gold, mercury, manganese, and marble. The United Nations Educational, Scientific and Cultural Organization (UNESCO) recognized the importance in preserving this eco-region and added five clusters of the Altai in the World Natural Heritage List.

The region is characterized by a continental climate with long, cold winters and short, cool summers. Snow starts covering the mountains during October and November, marking the beginning of winter. Temperatures hit the lowest in January, where they can range from 7 degrees F (-14 degrees C) in the foothills to -76 degrees F (-60 degrees C) in the STEPPEs. In northern Siberia, one can find vast areas of permanently frozen soil. Summers begin somewhere between May and July and end in September. During this time temperatures often reach 75 degrees F (24 degrees C) during the day. Temperatures of 104 degrees F (40 degrees C) have also been recorded in the lower regions. At night, temperatures get cooler, usually ranging from 41 degrees F (5 degrees C) to 50 degrees F (10 degrees C). Elevations of 5,000 to 65,000 ft (1,500 to 19,000 m) experience high precipitation, usually ranging from 20 in (50 cm) to 40 in (1 m) a year. One aspect of the summer that many people appreciate is the lack of mosquitoes.

Four vegetation zones can be found in the Altai Mountains: the mountain subdesert, steppe, forest, and the Alpine areas. The most widely used plants and trees are cedar, badan, kuril tea, and cannabis. The subdesert has very little plant life; the few plants that exist are drought-resistant and salt-tolerant. Many sod grasses and shrubs can be found in the steppe. The forest is generally swampy and covers a large area in the low to medium mountain area. Here are found pines, firs, larches, and birch and aspen forests. The meadows in the Alpine region are used for pasture during the summer.

Wildlife is abundant in this region. There are 230 species of small birds, like woodpeckers, and 20 species of fish. Big mammals like bears, lynx, and musk deer are found mostly in the forest. In the Alpine region live reindeer, mountain goats, rams, and even rare animals like snow leopards. Some areas in the mountains are inaccessible to locals and visitors because they are used to study rare species of animals and plants. The Altai Mountains are populated by mostly Altais and Russian settlers, many of whom moved there in the 19th century, mainly to escape religious persecution. The native population that was there before the 19th century continues to live in the old ways and is somewhat isolated from civilization. This area faces many challenges, especially with civilization knocking on its door. The big question is how to preserve the ecosystem and its natural beauty in spite of the increasing number of tourists and developments.

Alps

The Alps are Europe’s major mountain chain, occupying center stage between the cultural and geographic regions of western, eastern, southern, and northern Europe. Stretching in an arc about 600 mi (1,000 km) from west to east, the range covers parts of FRANCE, ITALY, SWITZERLAND, LIECHTENSTEIN, AUSTRIA, and SLOVENIA, with related features extending into GERMANY, CROATIA, and BOSNIA. 

Geologically, the mountains are at the core of even wider-reaching mountain systems, such as the Apennines and the Carpathians, and several lower chains on the outskirts (considered pre-Alps) such as the Jura in France, the Schwäbische Alb in Germany, or the Wienerwald in Austria—all were formed as a result of the collision of Italy and the Mediterranean floor with the landmass of Europe 150 million years ago. Several million people live within sight of the Alps, including residents of such major cities as Turin, Vienna, and Grenoble. The mountains—sometimes referred to as the “backbone” of Europe—have played a significant role in the history of Europe. Presently, the Alps are among the leading tourism locales in Europe, with about 100 million visitors per year, leading to challenges in growth such as overdevelopment and air pollution.

The origin of the name Alps is uncertain; it is most likely Celtic, perhaps for “white” or “high.” For many centuries the range was seen as a barrier between Mediterranean civilization and northern Europe, marked by heroic crossings like that of Hannibal with his elephants in 218 B.C.E. Mountain cultures in Switzerland, the Tirol, and southeastern France typically represented independence from authority and dogged defense of traditional freedoms, from William Tell to the perpetually neutral Swiss state of today. Gradually, the mountains were explored and valleys were settled. From the development of climbing as a sport in the 19th century and the engineering marvels of lengthy tunnels of the 20th century, the Alps ceased to be a threatening impasse, a land of avalanches and evil spirits, and became a recreation spot instead, a place of beauty. Notable sporting centers include Winter Olympic sites at Grenoble, Chamonix, Albertville, Garmisch, Innsbruck, and Cortina and ski complexes as Zermatt, Saint Moritz, and Bad Gastein.

There are numerous peaks over 12,000 ft (3,500 m), more than 1,200 glaciers, high carved-out circular basins called cirques, and sharp crags known as aiguilles. Long, narrow valleys separate high peaks, creating dramatic views, often accentuated by large, elongated lakes. These lakes are relics of the last Ice Age when glaciers dug deep trenches between the ranges: Lakes Maggiore and Como in Italy, Lakes Geneva, Neuchâtel and Constance in Switzerland, and the series of interconnected lakes in central Switzerland are all generally long and very deep rather than wide.

Other valleys were cut by swift mountain streams that form some of Europe’s major rivers: the RHÔNE, the RHINE, the Po, and several major tributaries of the DANUBE, the Inn, the Mur, the Drava, and the Sava. These rivers carry water from the Alps as far away as the MEDITERRANEAN, North, and BLACK seas. The Alps are traditionally divided into three sections, Western, Central, and Eastern, with numerous subdivisions within these. The border between France and Italy is delineated by the Maritime Alps, with peaks that emerge almost directly from the Mediterranean Sea, followed by the Cottian, Graian and Dauphiné (or Delphinic) Alps, and the Mont Blanc complex. Gran Paradiso, in the Graians, is the tallest peak entirely within Italy (13,648 ft or 4,061 m). Directly to the north is the double summit of Mont Blanc(15,771 ft or 4,806 m), the highest mountain in Europe outside of the Caucasus. The Mont Blanc massif is composed of several peaks and includes one of the longest vertical slopes in Europe (over 11,550 ft or 3,500 m), and the largest glacier in France, the Mer de Glace (“sea of ice”) on the Col du Géant. A 7-mi (11- km) tunnel directly beneath the mountain connects ski resorts in France and Italy.

After traveling mostly northward from the Mediterranean, the Alpine chain turns a corner at the Mont Blanc group. Heading eastward, the mountains of the Central Alps form some of the highest and most famous portions of the Alps. Directly east of Mont Blanc, separating it from the Pennine Alps, is the Great Saint Bernard Pass, one of the highest passes in Europe and the site of a monastic hospice for travelers for nearly 2,000 years. The Pennines, forming the border of Switzerland and Italy, together with the parallel range of the Bernese Oberland to the north, form the quintessential Alps of postcard quality. Mountains such as the Matterhorn and the Jungfrau are immediately evocative of the Alps and Switzerland. The Pennine Alps contain 10 of the 12 highest peaks in the Alps. The Aletsch glacier is the largest in Europe, 16 mi (26 km) long, covering 50 square mi (130 square km).

The Central Alps also include the mountains of southeastern Switzerland, the Lepontine, Bernina, Glarner, and Rhaetian Alps. The Eastern Alps begin roughly at the watershed between the Rhine and Danube river basins. These chains tend to be less orderly in their organization, but continue to be more or less aligned in an east-west direction. The Austrian Alps include the Bavarian range on the border with Germany (including Germany’s highest peak, the Zugspitze, at 9,718 ft or 2,963 m, the Ötztal and Ortler ranges on the border with Italy, and the Höhe Tauern, with Austria’s highest mountain, the Grossglockner (12,461 ft or 3,797 m). To the south, the Italian Dolomites have a slightly different character, with more rocks and less snow. Along Austria’s southern frontier with Italy and Slovenia run the Carnic Alps, the easternmost part of the Alps proper. The Julian Alps are an offshoot to the south across Slovenia, with links to the lengthy mountain chain that runs down the length of the Adriatic coast, the Dinaric Alps.

Alluvium

THE SEDIMENT DEPOSITED by rivers is called alluvium. The name derives from the Latin word alluvius, meaning “washed up.” Alluvium comprises clay, silt and sand (in some definitions gravel is included) and derives from the erosion of rocks and soils in the upper reaches of river basins. The mineral characteristics of the alluvium thus reflect its origins. It is carried downstream until the energy or sediment-carrying capacity of the river diminishes and the water can no longer carry the sediment in suspension.

During carriage, the sediment may be altered in physical character because of sorting and attrition. Sorting involves the separation of particles on the basis of size with finer and thus less dense particles like clay being carried farther downstream than larger and coarser particles such as sand and gravel. Attrition occurs as sediment particles collide during transport; overall, this causes a reduction in particle size and a general rounding in shape as angular material is smoothed. The deposition of alluvium in river channels, on floodplains, in estuaries, deltas, and lakes takes place over time. The erosional, depositional, and attritional regimes of a river may also change over time depending on climate and land-use characteristics in the river catchment.

Alluvium is widespread globally. It may provide fertile agricultural land because it is rich in nutrients, and it has provided the means for some of the world’s great civilizations to develop and thrive. Examples include those of ancient EGYPT based on the NILE Valley, those of the Indus civilization in the valley of the same name, and those of ancient Mesopotamia in the Tigris and Euphrates Valleys. Today, some of the world’s most productive agricultural land is on alluvium, as are many of the world’s major urban areas, for example, LONDON, Bangkok, BUENOS AIRES, Cairo, MUMBAI (Bombay), and Shanghai. In many cases, there is conflict of interest in relation to land use as urban spread competes with agriculture and sediment extraction, such is the value and prized location of alluvial deposits.

Where alluvium comprises the fine particles of clay, it can be used for brick making and pottery, and where gravel predominates, it is sometimes excavated for use as road aggregate and building materials. If ore-bearing rocks occur in the upper catchment of a river, the alluvium resulting from their erosion may be sufficiently mineral rich to warrant extraction. The most important metallic minerals found in alluvium include tin, gold, and platinum. Precious stones such as diamonds may also be found if catchment rocks are a source of gem stones.

Alluvial Fan

THE U.S. COMMITTEE on Alluvial Fan Flooding recently defined an alluvial fan as “a sedimentary deposit located at a topographic break, such as the base of a mountain, escarpment, or valley side, that is composed of streamflow and/or debris flow sediments and that has the shape of a fan either fully or partially extended.” The fanned or delta shape of alluvial deposits from mountains is formed over many thousands of years by downward-flowing waters or mud leaving the confines of their channel and spreading out into a wider area. The increase in the width of flow causes a decrease in the depth and velocity of the rushing water, which allows the deposition of sediment. This sediment consists of sand, debris, clay, and gravel carried by the stream or river from higher elevations, which can spread over hundreds of miles or kilometers.

Erosion also plays a part in alluvial fan formation, as newer flows carry away or redistribute material deposited earlier. Fans that sit inactive through climate changes and tectonic activity over many centuries are also subject to weathering and wind erosion. Alluvial fans are built unevenly; varying amounts and size of debris, volume of water, and placement of previous deposits influence where the alluvium is left. Usually, the larger rocks are closest to the topographic break, while finer grains travel further before being deposited. Some areas of the fan build up more sediment than others over years. Overall, the slope of a fan is commonly under 10 degrees. A flash flood leaves a different pattern of deposits than a shallower and less violent stream of water. Alluvial fans can consist of evenly dropped sand or be riddled with channels and trenches of varying depths. The former is considered more dangerous, because the lack of paths for water makes predicting the pattern of future floods impossible.

Alluvial fans are most often found at the base of hills and mountains in arid or desert environments or

piedmont plains all over the world. They are very common in western North America; in PAKISTAN, IRAN, and other parts of the MIDDLE EAST; Europe, especially in SPAIN and ITALY; and the Andean areas of CHILE and ARGENTINA. They form where highlands border lowlands, and where the lowland basin area is smaller than the highland area. Often in mountainous terrain, two or more alluvial fans merge or cross each other. This forms a feature called a bajada or bahada, which extends into a flood plain. Like an alluvial fan, bajadas tend to be built of larger rocks and sediment near the mountains and channels that guide water to them, while finer silts mark their edges.

In the UNITED STATES, the Federal Emergency Management Agency (FEMA) can designate certain areas as natural hazards. After several catastrophic floods in the late 1970s, FEMA began to evaluate the risks of flooding to alluvial fans. Some fans that were still subject to flooding presented attractive, gentle slopes for commercial or residential development. FEMA now decides whether such sites are hazardous based upon how susceptible they are to alluvial flooding and flood occurrence over a 100-year cycle, and how predictable the course of the floods will be.

Aleutian Islands

Known as the Catherine Archipelago until 1900, the Aleutian Islands comprise some 150 islands in four groups, which are, in order of proximity to the mainland: the Fox, Andreanof, Rat, and Near Islands. The name probably derives from the Chukchi word aliat, meaning “island.” Geographically, the islands separate the Bering Sea from the PACIFIC OCEAN. They extend in an arc about 1,600 mi (2,560 km) into the Bering Sea off the west coast of ALASKA, to which they belong politically. Their total area is 6,821 square mi (17,666 square km) and the total population is approximately 12,050.

Geologically, the islands comprise limited sedimentary and metamorphic rocks but are mainly volcanic in origin and are located at the junction between the Pacific and North American tectonic plates. They are characterized by volcanic peaks representing a continuation of the Aleutian range of mainland Alaska. Some volcanic peaks remain active, including Makushin on Unalaska and Shishaldin on Unimak, which are the largest islands in the Fox group.

Climatically, the Aleutians are oceanic, with annual temperatures ranging on average from 30 degrees F (–1 degrees C) in January to 52 degrees F (11 degrees C ) in August. There is a 135-day growing season between May and September and annual rainfall is 80 in (2.03 m) with rain occurring all year with abundant fog. The natural vegetation is a mixture of Asian and American species comprising dwarf shrubs with grass-, sedge-,and herb-rich meadows in the lowlands and mosses, lichens, and alpine herbs in the uplands. Most of the islands are within the Aleutian Biosphere Reserve and Wildlife Refuge, which contains a unique mixture of marine birds and mammals.

The islands were colonized at least 8,000 years ago by hunter-gatherers migrating east from Asia when sea levels were considerably lower than today. The native people, the Ungangans, encountered by European explorers in the 1700s were named Aleuts. In 1741, the first European arrivals were Vitus Bering, a Danish seafarer in Russian employ, and Alexei Chirikov; they captained separate ships and each discovered different islands. Bering was shipwrecked and died on what is now called Bering Island in the adjacent Russianowned Komandorski Islands.

Thereafter, Siberian fur trappers established bases as Russia extended its influence in North America, leading to the exploitation of the Aleuts for labor and the large seal and otter populations for furs. That ended with the transfer of Alaska to the United States in 1867. Further development came with the discovery of gold in Nome in 1900 and the establishment of Dutch Harbor, Unalaska, as a shipping port. 

JAPANESE OCCUPATION

During World War II, the Aleutian Islands featured in hostilities between the United States and Japan. A naval base was constructed at Dutch Harbor in 1942, and following its bombing, the Japanese occupied several islands but were routed in 1943 by U.S. forces from bases on other islands. Underground nuclear tests were carried out on Amchitka (Rat group) in the 1960s and early warning radar systems, pointing toward Soviet Russia, were constructed during the height of the Cold War.

Today, sheep and reindeer herding are part of the economy, with some production of market garden commodities. Hunter-gatherer traditions involving hunting and fishing equipment, including basketry, are maintained by modern-day Aleuts. Fishing and hunting of seal are overseen by the federal government and only Aleuts are allowed to undertake such activities.

Alaska

Tje 49th state admitted to the union in U.S. history, Alaska is located northwest of the 48 contiguous states. It borders CANADA to the east, the PACIFIC OCEAN to the south, the Bering Sea to the west, and the ARCTIC OCEAN to the north. Alaska has several distinct physical regions. The southernmost region is named the Pacific Mountain System. The panhandle in the southeast mainly comprises the Alexander Archipalego, while south-central Alaska is made up of the Alaska Range, home to Mount MCKINLEY, or Denali, the highest point in North America at 20,320 ft (6,194 m). 

The coastal part of this region includes Prince William Sound and Cook Inlet. Lying southwest of the Alaska Range are the Alaska Peninsula and the ALEUTIAN ISLANDS. To the north of the Alaska Range, up to the Brooks Range, are low hill and valleys, or the Central Uplands and Lowlands. To the west are Alaska’s main river valleys (the state’s major river is the Yukon, flowing approximately 1,979 mi or 3,185 km) and to the north lies the state’s vast treeless tundra.

America’s northern state has a rich and diverse past. Before becoming a Russian colony in the 18th century, the land was populated by some 70,000 natives, living in the the interior and southeast portion of the area. Here, the Tlingit and Haidi tracked caribou and fished. The Aleuts who inhabited the outer Alaska Peninsula hunted seals, sea lions, and whales. And the Yupik and Inupiaq Eskimos lived in harsher conditions while hunting for caribou, seal, walrus, and fish.

In the 1740s, Russian fur-trading companies arrived on the Alaskan panhandle, and the way of life for the Aleuts was adversely affected. In 1778, the British explorer Captain James Cook visited the area, and a fur “rush” began. By the end of the century, British, Russians, and Americans were hunting in this newly formed Russian colony, governed by Aleksandr Baranov. The Russian colony, however, posed many problems for the Russian government. The distance from the Russian capital of St. Petersburg was difficult to overcome and food shortages were prevalent. The Russian settlements in northern CALIFORNIA were also failing as grain suppliers. In 1867, Russia sold its colony of Alaska to the United States for around two cents an acre. Many Americans questioned the deal and thus named the purchase “Seward’s Folly,” after William H. Seward, the U.S. secretary of state who negotiated the deal.

For the remaining period of the 19th century, the Alaskan territory failed to attract farmers. However, many speculators became involved in the whaling industry, and the Gulf of Alaska turned into a haven for salmon fishing. Between 1878 and 1899, mainly because of Alaska, American canned salmon exports grew significantly. In 1896, gold was discovered in the Klondike River claim in Canada’s Yukon territory, near the border with Alaska. Gold prospectors soon traveled north and traveled through Alaska, and many prospected in Alaskan gold claims. Coastal towns such as Valdez and Juneau (the capital) were created. The gold rush lasted for over a decade, but by World War I, speculators began to dwindle across the territory. In the 1920s, Alaska’s white population primarily gathered along main transportation routes and in certain mining areas.

The scene was virtually unchanged until the outbreak of World War II, which witnessed American military personnel being sent to bases in the area. By 1943, 124,000 military personnel inhabited Alaska, and fortifications were created in defense of the Japanese. The Alaska Highway was also finished during this period, which linked Alaska to Canadian railroads. The military remained in Alaska after the war, as part of the distance early-warning (DEW) radar stations to defend against possible Soviet missiles during the Cold War.

ALASKAN OIL

In 1959, Alaska achieved statehood. In 1968, an arctic oil field was found at Prudhoe Bay, and three years later, the Alaska Native Claims Settlement Act was negotiated, which set up the creation of the trans-Alaska pipeline. The U.S. government gave 44 million acres (18 million hectares) and $962.5 million to the indigenous people. In return, the native Alaskans forfeited their rights to make aboriginal land claims. Thirteen regional and around 200 village corporations have thus invested in oil drilling and other Alaskan industries. All of the native Alaskans are individual shareholders in these companies.

The pipeline from Prudhoe Bay to Valdez was constructed in the mid-1970s and resulted in incredible population increases to Fairbanks and Valdez. In the 2000s, oil money accounts for almost 80 percent of the state budget, and Alaska has become the United States’largest oil-producing state. The money from the oil business has improved education, transportation, medical care, and communications.

Overall, Alaska has the highest average household income in the country. However, the effects of oil production continues to be debated across the state, especially after the Exxon Valdez oil spill, which affected Prince William Sound in 1989. This catastrophic oil spill of 10 million gallons damaged the ecosystem throughout the polluted area. In the early 2000s, debate centered on whether oil drilling should be conducted in the Arctic National Wildlife Refuge in the remote northeast corner of Alaska.

Ahaggar Mountains

The Ahaggar is a large mountainous plateau region lying on the TROPIC OF CANCER in the north-central SAHARA DESERT. It covers an area of 210,000 square mi (543,900 square km) which is about the size of FRANCE, or of ARIZONA and NEW MEXICO combined. It is about 1,000 mi (1,609 km) east of the ATLANTIC OCEAN, 1,000 mi north of the BIGHT OF BENIN, and 1,000 mi south of the MEDITERRANEAN SEA.

Most of the Ahaggar lies in southeast ALGERIA about 900 mi (1,450 km) south of Algiers. However, small areas extend into NIGER in the south and LIBYA in the northeast. The Ahaggar is a part of the Mid-Sahara Rise, which stretches 1,300 mi (2,092 km) east to west and 965 mi (1,553 km) south to north. The Mid-Sahara Rise includes the Adrar des Iforhas Mountains in MALI and the Massif de l’Air Mountains in Niger. 

The Sahara lies on the African shield, a thick pre-Cambrian crystalline base. Geological studies have concluded that about 300 million years ago violent earthquakes of enormous proportions pushed up this central massif or plateau region of the Sahara. This was followed by volcanic eruptions that poured enormous beds of basaltic lava over the area.

The geologic activity underlying the Ahaggar plateau pushed its granite base up thousands of feet above the Sahara. The Ahaggar plateau’s height is above 3,000 ft (915 m). The geologic activity produced enormous cliffs and fissures. These were broken into strange formations. At the heart of the Ahaggar, volcanic eruptions produced pumice and lava beds in many areas, some of which are basaltic. There are also “organ pipes” or volcanic needles or spires of rock that may reach 1,000 ft (305 m) high.

The Ahaggar Mountain chain, which is also called the Hoggar Mountains, is situated on top of the Ahaggar plateau. The plateau is like a platform covered with lava fields. The Tuaregs call the platform the Atakor, while the Arabs call it the Kudia. The Atakor platform averages 6,600 ft (2,012 m). At the heart of the Ahaggar chain is the Atakor range, which has extinct volcanoes in many places that rise to about 9,000 ft (2,743 m). They rise from the plateau and are the highest portion of the plateau. At the center of the Ahaggar Mountains is the highest peak, Mount Tahat (9,573 feet or 2,918 m). Other peaks include Mount Atakor and Mount Assekrem, which is where the Berber Tuaregs locate the “end of the world.”

While most of the Ahaggar is waterless and totally bare of vegetation, there are occasional snows. In some places in deep ravines, there are verdant strips that can be seen on aerial photographs. There are two waterfalls in the Ahaggar. One is at Tamekrest and the other is at Imeleoulaouene. A variety of animals live in the mountains along with the nomads, mostly Tuaregs, who frequent the oases located in these rugged reaches.

Afghanistan

Area 250,000 square mi (647,500 square km) 

Population 28,717,213

Capital Kabul 

Highest Point 24,550 ft (7,485 m) 

Lowest Point 846 ft (258 m) 

GDP per capita $700 Primary

Natural Resources natural gas, petroleum.

THE STATE OF AFGHANISTAN is a landlocked country that borders PAKISTAN to the south, IRAN to the west, TURKMENISTAN, UZBEKISTAN, and TAJIKISTAN to the north, and CHINA to the northeast. The country is divided into 32 provinces. Since the overthrow of the Taliban in 2001, Afghanistan is in the process of reconstructing its government.

Afghanistan, known since ancient times for its lapis mines, is divided by several mountain ranges. Cutting the country in half is the HINDU KUSH, from which smaller ranges project: from the Band-I-Turkestan on the west to the Suleiman Range to the east. To the southeast is the Dasht-I-Margo desert. Afghanistan has a dry climate with hot summers and cold winters. The country experiences sparse rainfall. Its chief rivers are the AMU DARYA, the Kabul, the Helmand, and the Hari Rud. Major cities include Kabul, Kandahar, Herat, Mazar e-Sharif, Jalalabad, and Konduz. 

ANCIENT LANDS

The region in and around Afghanistan has been inhabited since the Paleolithic and Neolithic eras. Afghanistan has been the scene of migrations throughout history. Since ancient times, Afghanistan captured the interest of foreign peoples. The region of what is now Afghanistan entered into recorded history under the PERSIAN EMPIRE. By 331 B.C.E., Alexander the Great extended his empire into Afghanistan after conquering Persia. Alexander’s empire disintegrated after his death in 323 B.C.E. with Afghanistan passing to Seleucis Nikator, one of his generals. Afghanistan soon after came under the control of Chandragupta from INDIA.

Around 650 C.E., ISLAM came to Afghanistan through Arabs who conquered the Sassanids in Persia. In 1219, the Mongols under Genghis Khan spread destruction throughout Afghanistan. For 500 years, Afghanistan was part of the power plays between the Mughals in India and the Safavids in Persia. In the 18th century, Afghanistan was united for the first time under Ahmed Shah Durrani, who created an empire that included modern-day Pakistan.

By the 19th century, Afghanistan was caught in the middle of the imperial ambitions of Britain, which had controlling interests in India and RUSSIA. Britain fought two wars to gain control of Afghanistan, both of which ended disastrously. In the 20th century, Afghanistan entered a period of modernization through King Amanullah between 1919 and 1929. In 1933, King Mohammad Zahir Shah extended the modernization through the creation of a constitution and a parliament. However, by the 1960s, the communists had gained a foothold in Afghan politics, and by 1973, Sardar Mohammad Daoud abolished the monarchy and established a republic with financial backing from the Soviet Union.

In 1979, the Soviet Union invaded Afghanistan to support a communist government under the Najibullah regime. Soviet occupation was met by fierce resistance by the Mujahideen, who were mainly supported by the United States. In 1989, the Soviets withdrew from Afghanistan, prompting civil war among the Mujahideen. By 1996, Afghanistan fell under the rule of the Taliban, a fanatical extremist Muslim sect. The Taliban imposed Sharia law as the legal system for Afghanistan and severely restricted women’s rights.

Additionally, Afghanistan became a breeding ground for international terrorism, harboring Osama bin Laden, leader of the al Qaeda terrorist group that masterminded the attacks in New York City and Washington, D.C., on September 11, 2001. In November of that year, the United States led a coalition of nations to overthrow the Taliban regime, when it would not surrender bin Laden. The Taliban offered no significant resistance and retreated to the mountains. At the end of 2001, an agreement was reached in Bonn, Germany, to lay out a blueprint for Afghanistan’s reconstruction. Afghanistan has a diverse array of ethnic groups.

The Pashtun are the majority ethnic group, followed by Tajiks, Uzbeks, Hazara, Aimaq, Turkmen, Baluch, and Nuristani. Pashto and Dari are the main languages spoken. Twenty years of war have left Afghanistan’s infrastructure in ruins. Agriculture makes up 60 percent of the economy. Afghanistan is one of the leading exporters of opium, which is most profitable for farmers to grow.

Afars

The Afar people live in the rocky desert terrain of eastern Africa, in an area called the HORN OF AFRICA. Most of them live in the countries of DJIBOUTI, ETHIOPIA, and ERITREA. The territory, once known as the French Territory of the Afars and Issas, became Djibouti in 1977, when France gave the people their independence. Although most Afars live in the desert, some live in the Awash Valley and the forests of northern Djibouti. They number about 1.4 million in all. The name Afar comes from the first two letters of Africa and Arabia.

The Afars are a cohesive group and did not like having their territory broken up into the countries of Djibouti, Ethiopia, and Eritrea. The Afars in Djibouti are outnumbered by the Issas and were unhappy with the Issa leadership. There was much unrest among the Afars during the 1990s, but a peace accord was finally signed in 2001. Djibouti is important because of its Afars 5

The Aegean Sea lies between Greece and Turkey, bridging the lands of western Europe and the Middle East. strategic position at the mouth of the RED SEA. It serves as a port for goods leaving and entering eastern Africa. Although peace now reigns in Djibouti, the Afars are the target of economic and political discrimination.

The Afar people are tall and proud, with narrow, straight noses, thin lips, and small, pointed chins. The Afars are known as fierce fighters. They have managed to survive under the worst conditions in one of the hottest areas in the world. The Issas are their main enemies. A man is judged on his bravery and strength among the Afars.

The Afars subsist mostly on a diet of bread and milk, and many are malnourished. They are often anemic and are prone to malaria because of their poor diets. Historically a pastoral people, over half of the Afars live a nomadic life, moving their livestock wherever they can find grazing. They raise sheep, goats, camels, and cattle. Rainfall is sparse in the area, so the people are forced to move often in search of grass for their animals. Both droughts and floods have had a negative effect on the economy of the Afars. Some Afars living along the Red Sea fish for a living. The Afars have also mined salt for many years and export it to Ethiopia.

Most Afars embrace the Muslim religion, which differentiates them from other tribes in the area that are Christian. Muslim practices are supplemented with ancient animist customs as well.

Aegean Sea

The Aegean Sea is an arm of the MEDITERRANEAN SEA, located between the Greek peninsula to the west and TURKEY to the east. The Aegean is connected through the Dardanelles, the Sea of Marmara, and the Bosporus with the BLACK SEA, while the island of Crete is considered to be the southern boundary. In all, it is about 380 mi (611 km) long and 186 mi (299 km) wide. It has a total area of approximately 83,000 square mi (214,000 square km). As for the name Aegean, there are several explanations: 1) named after the town of Aegae; 2) derived from the queen of the Amazons, Aegea, who died in the sea; and 3) stemmed from Aegeus, the father of Theseus, who drowned himself in the sea when he mistakenly thought his son had died in a distant war. The formation of the sea occurred when the Tethys Sea or Seaway began to shrink over the last 120 million years as the approaching African and European plates closed off the Mediterranean and surrounding seas.

During the last Ice Age (2,000,000 to 18,000 B.C.E.), the shallow and narrow Straits of Gibraltar blocked off much of the ATLANTIC OCEAN waters, which led to a saline crisis as a high rate of evaporation in the nearly arid region created a shallow, briny basin. Even today, the generally shallow (average depth of 4,921 ft or 1,500 m) Mediterranean Sea has a low exchange rate with the Atlantic and is saltier. The maximum depth of the Aegean is found east of Crete, where it reaches 3,543 m (11,627 ft). The rocks that make up the floor of the sea are mainly limestone, though proximity to a plate boundary has allowed volcanic activity to alter it.

The Aegean is studded with numerous large and small islands that are the mountain peaks of Aegeis, the name given to a submerged land mass. The Aegean islands can be divided into seven groups: the Thracian Sea group, the East Aegean group, the Northern Sporades, the Cyclades, the Saronic Islands, the Dodecanese, and Crete.

North winds prevail over the Aegean Sea, although periodically, the cold gale-force Bora katabatic drainage wind thunders into the sea from the Balkans. The low tides generally follow those of the eastern Mediterranean. However, the tide of Euripus, the strait between Greece and the island of Euboea, demonstrates a violent and uncertain character, leading to the term the Euripus Phenomenon. Cold water masses with fluctuating temperatures flow out of the higher BLACK SEA, impacting the deep waters of the Aegean. The low concentration of phosphates and nitrates, necessary for marine life, limits fishing to sardines and sponges. Likewise, the barren, rocky soil hinders agriculture. Thus, tourism remains the major source of income for the Aegean coastal countries.

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Adriatic Sea

The Adriatic Sea (in Italian “Mar Adriatico,” in Serbian “Jadransko more”) is a northwest-to-southeast arm of the MEDITERRANEAN SEA. The sea separates the Italian peninsula from the Austro-Hungarian, Montenegrin, and Albanian littorals, and the Italian Apennine Mountains from the Balkan Dinaric Alps. The western coast is Italian and the eastern comprises slovenia, croatia, bosnia and herzegovina, serbia and montenegro, and albania. The name derives from the Italian town of Adria (Hadria), designating in early historic times the sea’s upper portion. The term was later extended geographically to the south.

The Adriatic has a total surface area of about 60,000 square mi (160,000 square km), with a maximum length of about 480 mi (770 km) and a width of nearly 100 mi (160 km); however, the Strait of Otranto, connecting the Adriatic and the Ionian Sea to the south, is 45 mi (72 km) in breadth. The mean depth is 133 fathoms (240 m), but the northern portion of the Adriatic is shallowest between the southern promontory of Istria and Rimini (about 25 fathoms or 46 m), where the low Italian littoral merges in the northwest into marshes and lagoons along the delta of the Po River. The freshwater Po and Adige are the major rivers flowing into the saline Adriatic and account for substantial silting. The Po’s sediment extended the coastline for 2 mi or 3.2 km within the last two millennia.

The area between Šibenik and Ortona (Croatia and ITALY) exceeds 100 fathoms (180 m) in depth, but west of Durrës (Albania) and south of Dubrovnik (Croatia), the basin exceeds 500 fathoms (900 m). The rocky east coast has many long and narrow islands with the long axes lying parallel to the mainland coast and elevations of a few hundred feet; larger islands such as Brac have elevations of 2,552 ft (778 m). There are more than 1,000 islands in the Adriatic, although only 66 are inhabited, notably near Venice (Italy), and Trieste (Italy).

Due to eutrophication and minimal tidal flow, making the sea a shallow, closed system, the Adriatic has notable water and air pollution yet remains an important tourism and fishing locale.

Aconcagua Mountain

Aconcagua Mountain lies west of Mendoza, argentina, entirely within Argentina, and immediately east of Argentina’s border with chile. The mountain is, at 22,834 ft (6,960 m), not only the tallest mountain in the Western Hemisphere, but also the highest outside of Asia. Its twin peaks, the northern of which is the tallest, can be seen from the coast of Chile 100 mi (162 km) away.

There are different interpretations of the origin of the name Aconcagua. It may be derived from the native Quechua akun (“summit”), ka (“other”), and agua (“admired” or “feared”). Thus, it is translated from Quechua as a summit that is feared or admired. Another version is that the name is derived from Arauca roots. Thus, Aconca-Hue is a Mapuche name for the corresponding Aconcagua River that, from Chile, “comes from the other side.”

The relatively new mountain was created by subduction of the Nazca plate beneath the South American plate. Geology of the Aconcagua area can be grouped in three basic time periods: a base that developed before the Jurassic period, Mesozoic sequences, and coverings from the Cenozoic period. Glaciers on Aconcagua include Lower Horcones Glacier, the Upper Horcones Glacier, the Los Polacos (or Los Relinchos) Glacier (a climbing route), and the Güssfeldt Glacier. Glaciers on Mount Aconcagua are, owing to more arid conditions, less pronounced than those to the south in Patagonia.

Most of the vegetation and wildlife, because of the aridity and the short growing season at high elevations, are concentrated below 13,123 ft (4,000 m). Typical vegetation is low-growing brush (steppe) adapted to low temperatures, thin soils, and high winds. Brush species include lena amarilla, vareta, and cuerno de cabra, with grass species including huecu and coirones. Wildlife such as the condor, mora eagle, puma, and red fox migrate to lower elevations during winter. Mountain mice hibernate on site. Streams harbor chorlos, churrines, and torrent ducks. Guanacos (similar to llamas) can gather in large groups. Hares introduced from Europe are plentiful. Aconcagua Mountain is a provincial park. It was included in 1983 as part of a network of 10 protected areas of the province of Mendoza.

It is designated as a Protected Wilderness Area, based on its scenic, recreational, cultural, genetic, and biodiversity values. These areas serve as a reference in relation to similar yet degraded habitats. General Don José de San Martín crossed the Andes near Aconcagua to liberate the Chilean area from the Spanish in 1817. His army of more than 5,300 men, 9,280 mules, and 1,600 horses crossed at more than 13,123 ft (4,000 m) in elevation. In 1835, Charles Darwin was one of the first European scientists to collect data about the mountain. In January 1985, a remarkable discovery was made by Argentine climbers—an Inca cemetery at 17,388 ft (5,300 m) in elevation. The site included circular stone walls, a mummy, and six statues—three human and three llama figures. Although the mountain is a large, singular massif, thus nicknamed the “Centinel del Piedra” (Stone Sentinel), various peaks around Aconcagua also surpass 16,404 ft (5,000 m).

Aceh

Aceh (full name: Naggroe Aceh Darussalam, meaning “the Abode of Peace”) is one of the three “special territories” among the 27 administrative provinces of indonesia. Its location, on the large island of SUMATRA in the northeast corner of the Indonesian archipelago, facing the Andaman Sea and the Straits of Melaka, makes it the closest Indonesian departure point to Mecca, from which it gets the label “veranda of Mecca.” The label is also appropriate on account of the evidence that the Acehnese have the longest history of conversion to Islam in Southeast Asia, dating back to the 9th century, and today as a group represent one of the most staunch adherents of the faith in the region.

Aceh was able to survive as an independent Muslim kingdom since its inception in the early 16th century up to the late 19th century, when it became entangled in a power struggle between British and Dutch colonial interests. Through an Anglo-Dutch treaty in 1824, the British transferred control of some of its possessions to the Dutch, who agreed to allow the independence of Aceh. In 1871, against the neutral positions taken by the Americans and Europeans, the British allowed the Dutch to invade Aceh, possibly to avert French encroachment in the region, but they were never able to pacify Acehnese resistance, which lasted until World War II. In 1949, the Dutch handed their possessions in the Malay Archipelago to Indonesia, without ever consulting Aceh.

The newly independent Indonesian government immediately dispatched troops to annex Aceh, resulting in widespread resentment of what was viewed as foreign occupation. In 1959, as a way of appeasing the Acehnese, Indonesia conferred on Aceh the status of a “special territory,” allowing a degree of autonomy in matters affecting religion, education, and provincial administration. While this move placated those in favor of a union with the rest of Indonesia, the pro-independent movement remained and subsequently went underground under the name Gerakan Aceh Merdeka (GAM), or Aceh Independence Movement.

In the face of secessionist movements in two other provinces (east timor and Papua), the central government declared Aceh as a Military Operations District (Daerah Operasi Militer) in 1989, in a large-scale effort to eliminate GAM. After a decade of oppressive campaigns resulting in nearly 3,000 casualties and the destruction of homes and sources of livelihood, military operations were withdrawn partly in response to worldwide protest and criticism against the Indonesian government.

As of late 2004, the outcome of the Acehnese struggle for independence remains to be seen. The options being deliberated in the media include: continue to fight for outright independence; hold a referendum to allow for popular choice whether to secede or not; or engage in a dialogue with the central government under United Nations auspices to uphold the agreements ratified in the “special territory” status. The most contentious issue concerns the right of the province to enjoy its resources (petroleum and timber).

This “Abode of Peace” was struck by a series of tsunamis, or tidal waves, on December 26, 2004, resulting in more than 100,000 deaths in Aceh and nearby areas of Indonesia. The tsunamis were created by a massive earthquake, registering 9.0 on the Richter scale, in the Indian Ocean. Into 2005, Aceh struggled not only with the issues of independence but also with rebuilding its flood-ravaged territory and economy.

Abyssal Plain

Located in the world’s oceans, an abyssal plain is a depositional surface on the seafloor. The plain is generally 13,000 to 20,000 ft (4,000 to 6,000 m), extending seaward from the base of a continental slope or from the seaward edge of an oceanic trench to the midocean ridge. The term plain implies that this part of the seafloor is a monotonous, uninteresting place. Actually, the plain is remarkable for its sediments, manganese nodules, and life forms.

Much of the abyssal plain consists of tiny particles of brown and red clays, contributed to the ocean by wind deposition and volcanic eruptions. The shells of microscopic marine organisms also make up a significant portion of the sediments. Quiet waters of the deep ocean do not disturb the particles as they accumulate on the ocean floor. Marine scientists study the sediments to glean data about the age of the ocean floor and changes in the ocean’s depth, temperature, salinity, and circulation. This information provides clues to geographers and other scientists about millions of years of change in regional and global climate.

Turbidites are distinctive layers of sediments on the edges of abyssal plains next to continental slopes. Turbidites come from river sediment deposited on the outer edge of the continental shelf. Turbidity currents move the sediments from the shelf to the plain. The currents are slurries of water and suspended sediments. They rush down continental slopes similar to an avalanche, and the resulting turbidites form tonguelike abyssal fans usually near the mouth of a river or submarine canyon.

Turbidites also spread farther out on the plain. They are less abundant in the pacific ocean than in the atlantic and indian oceans, because fewer large rivers supply sediments to the Pacific Ocean and its deep-sea trenches trap sediments, preventing their spread to the abyssal plain. Seamounts (submerged

mountains) rarely interrupt the abyssal plains of the Atlantic and Indian oceans, as turbidites in these

oceans bury most of the mountains. In contrast, many seamounts rise above the abyssal plains in the Pacific Ocean because of a paucity of turbidites there.

These mysterious, potato-size rocks litter the surface. They have thin concentric layers of metals such as iron, cobalt, copper, nickel, and manganese. Chemical reactions in the water add layers that are 0.4 to 8 in (10 to 200 mm) thick every million years. Scientists do not agree on how the nodules form. Some investigators feel that biological productivity in overlying waters control the accretion of metals.

Others argue that the midocean ridge’s hydrothermal vents, which exhale such metals from the Earth’s interior, are responsible. The metals have aroused interest in the nodules’ economic value. Presently, the nodules are too expensive to mine because of the cost of extracting them from the ocean floor. The abyssal environment is not conducive to life as we know it; it is perpetually dark and very cold, and the food supply is sparse. Moreover, hydrostatic pressure is enough to crush a person’s body to the size of a soccer ball. No plant life exists because of a lack of sunlight. The animals—primarily small worms, crustaceans, and mollusks—are scavengers. They live off bacteria on the seafloor and fecal pellets, bones, carcasses of large animals, and dissolved material that filters down the water column. Population densities are low owing to a harsh environment and scarcity of food.