GeologyPaleoecologyPaleontologyMarine Mammals and ResourcesFlora and FaunaClimate and Air Quality
Geology
Paleoecology
Paleontology
Marine Mammals and Resources
Flora and Fauna
Climate and Air Quality
People's desires and aspirations... (are) as much a part of the land as the wind, solitary animals, and the bright fields of stone and tundra. And, too, the land itself exists(s) quite apart from these.
Barry Lopez
Arctic Dreams
The most significant theme in the geological history of Beringia is the land bridge itself, which has intermittently been a dryland connection between Asia and North America. The land bridge was the result of lowered sea levels during the great ice ages, when vast amounts of water were stored in continental glaciers. The land bridge chronology is not well understood, and opinions differ as to the actual times and duration of the connection.
There was probably a very ancient connection, long before recorded glacial periods and before modern flora and fauna evolved. However, it was only during later connections in the past 30,000 years that humans and mammals migrated from Asia to North America, and some species migrated from North America to Asia. At times the land bridge may have lasted 5,000 years or more and may have covered a very broad area. During the last ice age glaciers did not completely cover the Seward and Chukotskiy peninsulas, although small islands of glaciation occurred in both areas (see the map of the Bering land bridge).
Besides the land bridge, the landscape is also an element of the common heritage of ancient Beringia. The land is characterized by mountainous areas, large sounds and lagoons which cut deep into the land, hot springs, lakes, and rocks of volcanic origin. There are ancient broad valleys and tundra, numerous lakes, winding streams, permafrost features, and graben landscapes.
Ocean waves have formed sandspits and seacliffs along the coastline, although seacliffs are more common on the Chukotskiy Peninsula.
Mineral deposits on both the Chukotskiy and Seward Peninsulas are rich and include anthracite and bituminous coal, tin, molybdenum, gold, and tungsten.
Many questions remain concerning the paleoecology of Beringia during the last 40,000 years. Among the most important is the question of productivity: Was the area an arctic steppe with richly productive grasslands supporting herds of ungulates like the present-day African Serengeti, or was it a landscape supporting only sparse, discontinous vegetation with a small, widely dispersed ungulate population? One possible scenario for the evolution of Beringia's plant and animal life is presented below.
Some 40,000 years ago the sea level lay not far below its present position. The land bridge was a narrow isthmus and may have been briefly flooded. Thermokarst ponds and lakes were scattered in lowlands and major river valleys. Loess was accumulating slowly on vegetated lowland surfaces. The diverse fauna included the mammoth, horse, bison, caribou, mountain sheep, steppe antelope, moose, camel, and wooly rhinoceros.
About 30,000 years ago the sea level was lowered, and progressively more of the land bridge became exposed. Beringia was essentially treeless; many sand-dune areas had been activated, loess was accumulating, but there was little reduction in the diversity of the ungulate fauna. The climate was drier than it is today.
The sea fell to its lowest level about 18,000 years ago, and the land bridge was a plain more than 1,000 km wide north to south and connecting North America and Asia. Unglaciated zones across Siberia, Alaska, and the Yukon formed a corridor with a high degree of biotic exchange. Extensive glaciers isolated the areas. Animals included the mammoth, bison, horse, caribou, mountain sheep, saiga, and musk ox. The land was almost treeless.
An abrupt climate change starting about 13,500 years ago resulted in a rapidly rising sea level that drownedthe continental shelves of the Bering and Chukchi seas. Dwarf birch proliferated, cottonwood trees grew in areas where they no longer grow, and aquatic plants and animals extended their ranges. The climate was characterized by snowy winters, a rapid spring snowmelt with floods, mudflows, and gully washouts, and warm, dry summers. The mammoth, horse, and bison disappeared. Grasses and herbs gave way to mosses and sedges, and the landscape assumed its present appearance.
In ancient times the lives of native people - Chukchis and Eskimos - were closely intertwined with the natural world, and they were dependent on it for their survival. Hunting, fishing, and gathering plants and berries provided for their subsistence, and a growing scarcity of these subsistence resources probably prompted the migration of people across the land bridge. Man has been in western Beringia for an estimated 30,000 years, but in eastern Berigia man has only been present about 12,000 years.
Sites on both the Chukotkiy and Seward peninsulas have been found containing pollens, wood and other plant parts, mammal bones, and animal parts ranging in age from Miocene (20 million years ago) up through the late Pleistocene (1 million years and later). Collectively, these may prove to be of great significance in understanding climate cycle and vegetation patterns, as well as the spread of life across the land bridge, even before the period of human migration.
The presence of fossil pollen and wood indicates that the peninsulas at one time supported a temperate forest of hardwoods and conifers. Younger Pleistocene fossils include extinct mammoth, bison, and horse. These fossils indicate the former abundance and diversity of large, gregarious ungulates in a region that now supports few large mammals.
Today, prehistoric Eskimo pithouses often contain the heads and bones of gray, bowhead, and beluga whales, walruses, polar bears, reindeer, and mountain sheep. They are remnants of a utilitarian people. The heads and bones of the bowhead whales were used as a building material for houses. Walrus and seal oil were used as fuel. Walrus tusks were used for making tools, hunting implements, and artwork.
Throughout Beringia marine mammals have been the most important component of the subsistence lifestyle of villagers. Hunting camps and transportation routes on both coasts show eveidence of the long history of marine mammal use.
The bowhead whale, a species found on the ice edge, has been central to native culture and subsistence lifestyles. It provides meat, skin, and blubber (rich in vitamins, protein, and fat), and baleen used in making tools and handicraft items. The whale hunt is a major focus of the native community. The preparation, the hunt, and the sharing of the whale is the fabric that still binds the society, just as it has for thousands of years.
Yankee whalers began taking whales in the Bering and Chukchi seas in 1848, and their activities laid the foundation for the U.S. purchase of Alaska in 1867. Over a period of time, however, those whales that summered in the Bering and Chukchi seas were almost exterminated by the commercial whalers. And today few bowheads are sighted in these waters.
The walrus, a Pleistocene relic mammal found on the ice edge, was regarded by Eskimos and other native people as having supernatural powers and human attributes. It was for them a resource of major importance, providing food and fuel, tools, shelters, boats, sleds, and clothing. Today, the walrus is harvested commercially by the Soviet Union, and natives on both sides harvest walrus for traditional subsistence pruposes. Ivory carvings from walrus tusks are made at a central factory in the Soviet Union and by individual natives in the United States.
The deplition of walruses and whales in the region eventually alerted governments to the need for conservation. The North Pacific Sealing Convention of 1911 established the precedent of mutual cooperation in resource management. Treaty regulation of whaling dates back to 1937, and a major quota agreement was achieved in 1966. Both countries jointly conduct a walrus population count at five-year intervals. An international joint management program would help to maintain healthy walrus populations.
Polar bears move great distances and, as a consequence, are a shared international resource. Polar bears associate with the ice edge, and they move north to south or south to north with the movement of the ice. Satellite transmitters show animals captured in Alaska move to Chukotka, and Soviet-tagged polar bears have been shot in Alaska. Polar bears are legally taken by Alaska natives. Restricted selective shooting and capture of cubs for zoos is allowed in both countries.
Other marine mammals important to the subsistence lifestyles of local villagers include seals (bearded, ringed, and spotted) and other whales (gray, beluga, humpback, fin, and orca). These animals are used for food, clothing, and handicraft items.
Salmon, grayling, char, and other fish species are locally important for subsistence. Whitefish and herring also occur, but they are less improtant to villagers. Shellfish are harvested by villagers.
Scientists consider Chukotka and northwest Alaska to be a single botanical area. The intermittent emergence of the Bering land bridge favored an exchange between the two continents, predominantly the dispersal of plants from Asia to America. One difference between the vegetation of Chukotka and Alaska is that the polar forest limit is formed by different tree species. These differences are related to the history of the Bering land bridge (see the map of Beringian heritage sites).
The continuum in tundra types is based largely on soil moisture and degree of drainage. Tussocks and polygons are common. Sedges, peat mosses, lichens, a few grasses, heaths, and willows predominate. Plants grow low to take advantage of the ground temperature and to avoid harsh winds. Villagers on both coasts collect berries from several species of shrubs.
Tundra-steppe and steppe associations appear on the Chukotskiy Peninsula, apparently as relics from the cold and dry Pleistocene epoch. Similar vegetation has recently been discovered on steep, south-facing river bluffs in Alaska.
Throughout Beringia willow thickets and some alder have developed along floodplains on new alluvial soils. These thickets form the principal cover and food for moose in Alaska, but the animals are absent on the Chukotskiy Peninsula.
The Chukotskiy and Seward peninsulas are extremely rich areas for birds. At least 170 species are known on the Seward Peninsula. This diversity is related in part to the nearness to Asia and also to the occurrence of marine/estuarine, tundra, and nearby boreal forest habitats. The Asian birds include some species that regularly migrate across the Bering Strait to breed on the Seward Peninsula. Some North American species go to Chukotka or farther to breed. Only five or six species can be found throughout the winter season. Willow and rock ptarmigan are common throughout the year on both sides of the Bering Strait.
The marine/estuarine areas, together with extensive freshwater ponds and lakes, provide habitat for large populations of migratory geese, ducks, sandhill cranes, and shorebirds. The stickleback fish is sufficiently numerous to provide food for many species of aquatic birds.
Colonies of seabirds are found on both coasts. The extensive high rock cliffs on the Chukotskiy Peninsula provide habitat for one of the largest concentrations in the world of kittiwakes, puffins, and glaucous gulls.
The tundra habitat supports the majority of passerine birds, as well as hawks, gyrfalcons, snowy owls, Steller's sea eagles, and other predatory birds.
Wolverines are found throughout the Chukotkskiy and Seward peninsulas, but they are scarce. Foxes, land otters, lynxes, arctic ground squirrels, hares, and numerous small mammals are found throughout both peninsulas. Beaver are present in Alaska but are absent from Chukotka. Fox farms are an industry at several villages on the Chukotskiy Peninsula.
Grizzly bears and wolves occur on both sides of the Bering Strait, although populations are not large for either species. Moose occur only on the Alaskan side. Prior to the 1950s moose were generally absent from northwest Alaska, but in the past 30 years moose range has extended considerably.
Caribou occur in large free-ranging herds to the north and east of the Seward Peninsula. These animals are a part of the western arctic caribou herd, which is comprised of over 300,000 animals. As the herd has expanded dramatically during the past few years, animals have moved farther onto the Seward Peninsula. With this expansion comes potential for conflict with reindeer herding.
Reindeer range throughout the Seward and Chukotskiy peninsulas. Reindeer husbandry includes herding, protection from predators, corralling, antler removal, slaughtering, and transporting to market.
On the Seward Peninsula the reindeer industry was envisioned as a means to provide the natives with a more dependable source of food. By law, only natives can herd reindeer in Alaska, and 12 herds on the Seward Peninsula are owned and managed by local residents and native corporations. The total reindeer population, which is currrently estimeted at 24,000, has been declining, in part because animals are lost to the caribou herds.
On the Chukotksiy Peninsula reindeer herding takes place on state farms. There are an estimated 32,000 reindeer. Some 150 herders lead a nomadic way of life, carrying their food, fuel, and housing on all-terrain vehicles.
Beringia today is influenced by maritime and continental climates. When waters are ice free, temperatures are moderate, humidity is high, and skies are typically cloudy, especially near the coast. Interior sections are somewhat drier and less cloudy. When offshore waters are frozen, both inland and coastal areas are drier and clearer. Winter temperatures do not reach the extreme lows encountered in interior areas. July mean temperatures of 9.7° C and 9.8° C have been recorded at Imuruk Lake in Alaska and at Perevalnaya on the Chukotskiy Peninsula, respectively. Annual precipitation is approximately 250 mm in both areas.
The 10° C isotherm, often correlated with the northern limit of the "tree line," is at the south and east edge of Bering Land Bridge National Preserve. This is several hundred kilometers north of where the isotherm is found on the Chukotskiy Peninsula.
Comprehensive data about air quality throughout Beringia are not available, but generally air quality is considered to be excellent. Arctic haze does occur in the region. Potential sources of air pollution include the Red Dog Mine road and port on the Alaska coast and coal-fired power plants in villages on the Chukotskiy Peninsula.
