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.