Relief and Hydrography
The term “relief” refers to all the landforms on the surface of the earth. It is basically the same thing as “topography.” “Hydrography” refers to the water features that produce some of the landforms. Every country has prominent features such as mountains, valleys, plateaus, and basins, which set the stage for climate types and biomes to develop, and these in turn determine to a large extent which human activities are possible. Surrounding every continent are peninsulas, islands, bays, gulfs, and seas. On land, lakes and rivers develop, depending on mountain systems and more local relief forms. The countries of the former Soviet Union (FSU) exhibit thousands of varied topographical and hydrographical features. Without knowing what and where they are, we cannot understand the region’s climate types, biological communities, or human landscapes.
The Main Physical Features
The FSU (this term is used interchangeably with Northern Eurasia in this chapter) has numerous geographic features on a physical map. When you arrive in Moscow on an international flight, the land appears very flat. This is because Moscow is located in the middle of one of the largest plains on earth, the Eastern European Plain, stretching from Poland to the Urals. On the other hand, if you were to take the Trans-Siberian Railroad into Siberia, in a day’s time you would be greeted by the Urals, and in less than 4 days by the Central Siberian Plateau and the mountains surrounding Lake Baikal.
Examine the map of Northern Eurasia and the associated list of some important physical features. Some features in this region are unique (biggest, deepest, highest, etc.). Here are some examples:
- Mt. Elbrus in the Caucasus is the tallest mountain in Europe and all of Russia, at 5,642 m (the famous Mt. Blanc in the French Alps is only 4,807 m).
- Ismail Samoni (formerly Peak Communism), in the Pamirs in Tajikistan, is the tallest mountain in the FSU (7,495 m). It is only 1,500 m shorter than Mt. Everest, but is considerably higher than any summits found in the two Americas.
- The lowest point in Russia is on the north shore of the Caspian Sea, at 28 m below sea level.
- Lake Baikal is the deepest lake on earth, at 1,620 m, and the biggest by freshwater volume (it contains 20% of the world’s liquid freshwater—the equivalent of all five Great Lakes in North America combined). The Caspian Sea is the world’s •• largest saline lake. Its surface is four times greater than Lake Superior’s.
- The Ob–Irtysh river system is the fifth longest worldwide, at 5,400 km (the Mississippi–Missouri system is fourth, at 6,019 km). Note that the Irtysh is the longer of the two rivers where they merge, but the Ob carries more water, so the combined river downstream retains the name Ob.
- Sakhalin Island is the biggest in Russia, with over 76,000 km2. It is the 22nd biggest worldwide, about the same size as Hokkaido (Japan) and Hispaniola (in the Caribbean). Located in the Far East, it is over 900 km long, but only about 100 km wide.
- The Taymyr Peninsula is the biggest and northernmost in Russia. It ends at Chelyuskin Point (77?43’N), named after a famous Arctic explorer. In comparison, Alaska’s northern shore is located at 72?N. The northernmost point of Russia on an island is Cape Fliegeli on Franz Joseph Land’s Rudolf Island at 81?51’N, just 900 km south of the North Pole. The Soviet Union unilaterally claimed all the Arctic Ocean north of its shores all the way to the North Pole. The current Russian government is trying to get this claim recognized, but so far it has met with fierce resistance from Canada, the United States, and Norway.
- The southernmost point of Russia is Mt. Bazardyuzyu in Dagestan (41?10’N). For the remainder of the FSU, it is the city of Kushka in Turkmenistan (36?N).
- The westernmost point of Russia is on the border with Poland, on the Baltic Spit in Kaliningrad Oblast (19?38’E).
- The easternmost point of Russia is actually located in the Western Hemisphere! Dezhnev Point at 169?40’W, overlooking Alaska, is on the continent of Eurasia. Ratmanov Island in the Bering Strait is even closer to the United States, but it is not on the mainland (169?02’W).
Russia is enormous: It stretches for about 4,500 km from north to south, if the islands in the Arctic are included, and for 9,000 km from west to east. As noted in Chapter 1, it covers 11 time zones—definitely the world’s record. (The entire country was placed 1 hour ahead of the true solar time by a decree of Lenin in 1918, thus effectively putting the whole country on daylight savings time. In the late 1980s, an additional hour of summer daylight savings time was introduced, beginning on the last Sunday of March and ending on the last Sunday of October.) If you are flying on a passenger jet from Moscow, it takes just 2 hours to reach Sochi or Murmansk; about 3? hours to reach Paris or Tyumen; 4 to reach Novosibirsk; 7 to reach Khabarovsk; 8 to reach Magadan; and 9 to reach the Chukchi Peninsula. In comparison, nonstop flights from Moscow to New York City take about 10 hours.
Notice that whereas mountains in Northern Eurasia tend to run from east to west, the rivers mainly run from south to north, especially in Siberia. The Urals run from north to south; they divide Russia into its western (European) part and its eastern (Siberian) part, and separate Europe from Asia. The Volga flows mainly south and east into the Caspian Sea, and the Amur flows mainly east along the Chinese border into the Sea of Okhotsk.
The Geological History of Northern Eurasia
Older, Larger, More Stable Landforms
Like any other large landmass on our planet, Northern Eurasia has a long and complex geological history. However, the sheer size of Eurasia makes its geology particularly complex—unlike that of relatively simple and flat Australia, for example. The two largest “chunks,” the Eastern European and Siberian platforms, are over 1,700 million years old, which is comparable to the age of the North American plate. They are two separate continental plates that were driven together by geological forces over long periods of time. About 550 million years ago, the two were still separate, drifting in the warm seas of the Southern Hemisphere. However, they came together about 500 million years ago, and the Urals formed between them about 220–280 million years ago. The Eastern European platform underlies much of what is European Russia and Ukraine today. The Siberian platform is found east of the Yenisei River and west of the Lena. Parts of the Northern European plate are occupied by the Scandinavian and Baltic crystalline shields, which, like their Canadian counterpart, have some of the oldest rocks on earth (some over 2 billion years old) exposed at the surface. Other very old shields with rocks over 1 billion years of age are exposed in the northern part of the Siberian platform, called the Anabar Massif, and in the eastern part, the Aldan Plateau east of Lake Baikal. The oldest rocks here can be about 3 billion years old. Some of the famous gold and diamond deposits that formed in the Proterozoic period (about a billion years ago) are found in that area.
East of the Urals, the Western Siberia Lowland is covered with sea deposits from the Jurassic and Cretaceous periods (65–195 million years ago). This was a time of great warmth, supporting tropical plants and dinosaurs. This area can be compared geologically to parts of Colorado, Utah, and Wyoming in the United States, which were likewise submerged under the warm tropical sea at the same time and today have many dinosaur fossils. The vast oil and gas deposits of Russia date back to that time and are primarily concentrated in western Siberia.
Higher Mountains, Tectonic Movement, and Volcanoes
In contrast to these large and stable areas, many areas to the east and the south have a much more complex and recent history. In southern and eastern Siberia, some mountains south of Lake Baikal were formed by tectonic uplift in the Proterozoic era (over a billion years ago); the Altay and Sayans were similarly formed in the mid-Paleozoic (450 million years ago); the Sikhote-Alin and other Far Eastern ranges were thus formed in the Mesozoic (225 million years ago). The highest mountains are also the youngest: The Caucasus, the Pamirs, and the Tien Shan were formed primarily in the past 10–15 million years and are still exhibiting uplift today. They are part of the Alpine–Himalayan fold belt, which stretches from the Alps in Europe to the Zagros Mountains in Iran to the highest mountains on earth, the Himalayas in India and Nepal. This dramatic uplift began when the Indian subcontinent slammed into Eurasia from the south 40–50 million years ago. This same event apparently started the Baikal rift that produced Lake Baikal, the oldest lake on the planet, by about 25
million years ago.
The eastern and southern fringes of the FSU are mountainous, with active tectonic movement, frequent earthquakes, and (in the Russian Far East) active volcanism. Earthquakes reaching a magnitude of 7 on the Richter scale were recorded in the past in the Carpathians and the Caucasus, with magnitudes over 8 recorded in the Pamirs, the Tien Shan, the area east and north of Lake Baikal, and Kamchatka. Massive earthquakes devastated Ashgabat (1948, 100,000 casualties) and Tashkent (1966), two Soviet capitals in Central Asia. More recently, the Armenian earthquake of 1988 killed about 20,000 in Spitak, and the Sakhalin Island earthquake of 1995 caused about 3,000 fatalities in Neftegorsk. Most of these casualties were people trapped under poorly constructed concrete buildings, built in the Soviet period without regard to seismicity. Ninety percent of Northern Eurasia is earthquake-free, the chance of experiencing one in Moscow is close to zero. The greatest risk of earthquakes is in the mountainous belt in the south, especially in Moldova near the Romanian border; in Armenia and Georgia in the Caucasus; in Tajikistan; in the areas south and especially northwest of Lake Baikal; on Sakhalin Island; and, of course, in Kamchatka.
The Caucasus has a complex geological history, but essentially represents one long mountain wall trending from northwest to southeast, with associated smaller ranges extending north and south (average elevation 3,000 m). It is bigger, but less geologically complex, than the Alps. An extinct volcano, Mt. Elbrus (5,642 m), with two summits, sits to the north of the main range. The second highest point of the range in Georgia is Mt. Kazbek (Kazbegi; 5,033 m), to the southeast. Most of the Caucasus has granitic rocks, with a higher incidence of limestone farther east. Glaciers and perennial snowfields attract downhill skiers and mountaineers, to Dombai in Karachaevo-Cherkessia, Baksan in Kabardino-Balkaria, and Krasnaya Polyana near Sochi (the future home of the 2014 Winter Olympics). The north slope of the Caucasus has over 1,230 km2 of glaciers, the most of any mountain range in Russia.
The highest mountains in the FSU are the Pamirs, which lie within Tajikistan and the Tien Shan (“Heavenly Mountains” in Chinese) in Kyrgyzstan and parts of Kazakhstan and China. Some peaks there rise above 7,000 m, higher than any summit in the Western Hemisphere. These ranges are the source of most river water and hydropower in Central Asia. They are also premier climbing and backpacking destinations. The Altay and the Sayans in south central Siberia farther to the east are a bit lower than the Pamirs; they are comparable in height to the Caucasus or the Alps. They are complex mountain systems, with multiple ranges and substantial glaciers and snowfields. The Ob and the Yenisei originate in the Altay and the Sayans, respectively. More mountain ranges exist east of Lake Baikal (the Baikalsky, Barguzinsky, Yablonovy, and Stanovoy ranges) and in northeastern Russia (the Cherskogo and Verkhoyansky ranges). All of these are between 2,000 and 3,000 m in elevation, and have little glaciation despite being located in very cold places, because of the aridity so far inland. Along the Russian Pacific Coast runs the Sikhote-Alin range.
The volcanoes of the Kamchatka Peninsula and the Kuril Islands are legendary. About 28 active and 160 extinct volcanoes are found on Kamchatka, and 39 are active on the Kurils. The highest is the Klyuchevskaya Sopka, at 4,750 m in the central part of the peninsula. The skyline of the main seaport, Petropavlovsk-Kamchatsky, is dominated by the Avachinsky and Koryaksky volcanoes (3,500 m each). The central part of Kamchatka encloses a famous Geyser Valley, with 19 active geysers and 9 pulsing thermal springs, rivaling some Yellowstone and New Zealand counterparts. The Velikan (“Giant”) geyser produces a pillar of boiling water 35 m high, with steam rising to an astonishing 250 m, which is the height of an average skyscraper in Seattle or Minneapolis. Massive eruptions are known to have occurred in Kamchatka in the late Pleistocene (20,000–30,000 years ago) and in the mid-Holocene (7,500 years ago); some blasts produced enough ash to be found in substantial layers in Greenland’s ice sheets, on the other side of the world! One of the most famous recent eruptions came without warning from Bezymyanny in 1953, with a powerful explosion comparable to that of Mt. St. Helens in Washington State in 1980. It did not kill any people, fortunately, because nobody lives in that area.
Ice Ages and Their Impact
As in North America, the Ice Ages of the Pleistocene made a profound impact on the landscape of Northern Eurasia, from 2.4 million years ago until approximately 10,000 years ago. Unlike in North America, however, there was no single giant ice sheet that covered the entire northern half of the continent. The biggest ice sheet covered all of Scandinavia and extended east as far as the eastern shore of the White Sea today. The Urals and parts of the Putorana Plateau in northern Siberia were also heavily glaciated. In between, however, and all the way to the Pacific Coast, only small areas of the highest terrain had much ice cover. The remainder was ice-free, but with hundreds of meters of permafrost extending deep into the soil. This may seem counterintuitive, but it can be understood if we remember that moisture available at cold temperatures is what makes ice and snow, not the cold temperatures themselves. Readers living east of the Great Lakes in the United States are no doubt familiar with the “lake effect” on snow formation: In a typical winter, parts of Ohio and upstate New York may get 10 feet of snow, while much colder North Dakota and northwestern Minnesota may get only a few inches. A similar effect operated in Eurasia during the Ice Ages. The area closest to the ice-free Atlantic Ocean, Scandinavia, received the most snow and consequently developed the most ice, while the colder parts farther inland received virtually no snow or ice.
Another impact of the Ice Ages was a worldwide lowering of the sea level by about 60–120 m, depending on the glacial stage, because much ocean water was frozen in the ice sheets on land. As a result, Eurasia was connected to North America via the Bering land bridge; Sakhalin Island was connected to Japan and the Eurasian mainland; and most Arctic islands were likewise connected to the Eurasian mainland. An amazingly rich fauna of large mammals existed in the ice-free cold areas in Siberia and the Russian Far East, with now extinct species (e.g., mammoth, woolly rhinoceros, camels, horses, saber-toothed tigers, and giant short-faced bears) mingling with some still-existing animals (e.g., musk oxen and bison). The abrupt end of the Ice Ages about 12,000 years ago, and the widespread arrival of human hunters in northern and eastern Siberia and in North America about 13,000 years ago, apparently led to the extinction of most of the 40 or so megafauna species. The last, albeit dwarfsized, mammoths persisted until about 4,000 years ago on the lonely Wrangel Island of the northeastern Siberian coast—almost up to the time of the Egyptian pyramids!
The Ice Ages left numerous landforms in European Russia, including the morainal Valdai Hills and beautiful glacial lakes (Seliger, Ladoga, Onega, and hundreds of lakes in Karelia) north of Moscow. Large areas of drumlins, kames, eskers, and other glacial landforms familiar to Finns, Minnesotans, or Canadians are present in much of northern European Russia. The areas south of the ice sheets—in modern-day Ukraine; in the Bryansk, Kursk, and Voronezh regions of Russia; and in northern Kazakhstan and western Siberia—have extensive loess deposits consisting of fine wind-blown dust that came from the glaciers. The best chernozem soils producing the highest yields of grain in Ukraine and Russia owe their origin to these loessal deposits. The areas north and east of the Caspian and the Aral Seas have evidence of giant glacial outburst floods, like those in the Columbia Basin in Washington State. The rushing meltwater roared down from the ice fields of Siberia and the southern Urals toward the southwest and carved curious parallel channels, which are clearly visible from space today (e.g., use Google Earth and examine the areas north and northeast of the Aral Sea).
Originally, it was thought that only four major glaciations occurred, based on incomplete evidence from terrestrial records in Europe and North America. Deep drilling in the oceans since the 1970s has allowed scientists to conclude that in the past 2 million years over 20 glaciations occurred worldwide, once every 100,000 years—each lasting about 80,000 years and separated by milder interglacial periods, like the one we are living in now. In European Russia, the most recent glacial stage is called the Valdai, after the Valdai Hills halfway between Moscow and St. Petersburg (a national park today). It corresponds to the W?rm or Weichsel stages in Europe and the Wisconsinian stage in North America. The last interglacial period before the current one, Mikulino, happened about 120,000 years ago. Before that, the Dnieper glacial stage occurred in European Russia, corresponding to the Illinoian stage in North America between 120,000 and 200,000 years ago. As can be seen from its name, that ice sheet extended farther south than the Valdai, to the Dnieper River in modern-day Ukraine.
Russia has over 120,000 rivers over 10 km long, which collectively create 2.3 million km of waterways. Fifty-four percent of their flow enters the Arctic Ocean, with only 15% entering the Pacific. Another 8% of water flows to the Atlantic Ocean via the Black and Baltic Seas, and 23% to the Aral–Caspian interior basin with no outlet to the ocean. Russian schoolchildren learn in the early grades that “the Volga flows to the Caspian Sea.” This is interesting, because the biggest river in Europe does not even flow to the ocean! North America also has a few interior basins, the most famous being the Great Basin that includes the Great Salt Lake.
Northern Eurasia has a few of the world’s largest rivers. The Volga is the biggest and longest river of Europe. Russians call it Matushka, meaning “Dear Mother,” because their civilization developed around it. The basin occupies only 8% of the country, but is home to 40% of its population. Other important rivers in the European part of the FSU include the Northern Dvina and Pechora in the North; the Neva, flowing from Lake Ladoga to the Baltic Sea, with St. Petersburg at its mouth; and the Dniester, Dnieper, and Don in Moldova, Ukraine, and southern Russia, respectively. The “dn” root in the names of some rivers is not a coincidence; it probably comes from dno, meaning “bottom” or “low place” in the Slavic languages. The Volga, the Dnieper, and the Don are heavily tapped for hydropower, with many reservoirs behind dams. Dams slow the speed of water flow and increase evaporation off the reservoir surfaces, especially in the arid south. Irrigation and industrial and domestic consumption further reduce the flow. The Volga loses 7% of its annual flow to human consumption. Its flow has been reduced by about 20% in the last 100 years.
The Siberian rivers primarily flow north to the Arctic Ocean, with the exception of the Amur, which flows east into the Pacific. Four of the great rivers in Siberia are comparable to the Mississippi in length and flow. The Yenisei and its tributaries, and to a lesser extent the Ob and the Irtysh, are tapped for hydropower. The Lena itself remains dam-free, with a few dams existing on its tributaries, and more dams on the Amur tributaries farther east. Because spring comes earlier in the south, north-flowing Siberian rivers are prone to catastrophic spring flooding, similar to the Red River of the North in North Dakota. While the spring meltwater is abundant in April in the Ob and Irtysh headwaters, the rivers are still solidly frozen in the far north. Thus a huge seasonal “pond” appears in the middle of western Siberia, creating great inconvenience for the residents.
Central Asia’s main rivers are the Amu Darya and the Syr Darya; both now barely reach the Aral Sea because of irrigation diversions. The Kara Kum canal, dug in the 1950s to divert the Amu Darya water for cotton irrigation in Turkmenistan, was the longest in the country at 1,100 km. The total amount of diverted runoff in Soviet-era Central Asia approached the annual flow of the Dnieper, the largest river in Ukraine! Some short but powerful rivers flow from the Caucasus to the Black and Caspian Seas (the Kuban, Terek, Rioni, and Kura) and from the mountains of Central Asia (the Zerafshan and Vakhsh). These are tapped for irrigation and hydropower, but most are used for recreation and local water consumption.
Lake Baikal is the oldest and deepest lake on the planet. It sits in a rift valley where the earth’s crust spread apart about 25 million years ago. Baikal is almost 1 mile deep in places and covers 31,500 km2. Some of its closest counterparts exist in East Africa (e.g., Lake Tanganyika, which is the second deepest lake in the world). Lake Baikal holds an astonishing 23,600 km3 of freshwater, which is about one-fifth of the global liquid supplies of freshwater, as noted earlier in this chapter. The biggest lake of all, however, is the Caspian Sea. Its salinity is only about one-third that of the world’s oceans. The Aral Sea and Lake Balkhash are also saline, but are much smaller. Lake Balkhash is famous for being fresh in its western half near the mouth of the Ili River, but saline in the eastern half. Lake Issyk-Kul in Kyrgyzstan is another great and famous lake of the region. It is fresh, relatively clean, nd extremely picturesque, with many resorts lining its mountainous shores. East of St. Petersburg, Lake Ladoga is the biggest in all of Europe (with 17,700 km2 of surface), followed by Lake Onega (about half the size). Both are glacial in origin, like the North American Great Lakes.
Coastlines and Islands
The coastlines of the U.S.S.R. were among the longest on earth. Russia’s current coastlines total about 37,000 km, third longest in the world after Canada’s (202,000 km with all the Arctic islands) and Indonesia’s (54,000 km). The U.S. coastlines are only 19,000 km by comparison. Most of Russia’s longest coastline follows the Arctic Ocean coast. In Russian, the Arctic bears the name of “Northern Icy Ocean” for a good reason: For much of the year, ice comes right up to the shore. Therefore, although the coastline is long, sea travel there is very difficult. Russia has only one big year-round ice-free port in the European Arctic, Murmansk. St. Petersburg, much farther to the south, generally ices up, but Murmansk remains ice-free courtesy of the warm North Atlantic current. The second longest coast of Russia is along the Pacific Ocean, with Magadan, Petropavlovsk, Yuzhno-Sakhalinsk, Vladivostok, and Nakhodka as ports. Historically significant for the Russian Empire and later the U.S.S.R. were also ports on the Black Sea (Odessa, Sevastopol, Novorossiysk, Batumi) and the Baltic Sea (St. Petersburg/Leningrad, Tallinn, Ventspils, Klaipeda, Liepaja, Kaliningrad). The internal ports of Astrakhan, Baku, Atyrau, and Aktau allow fishing and trade in the Caspian Sea basin.
Along the coast, a few physical features merit special mention. In the Black Sea, the prominent Crimea Peninsula in Ukraine is a famous resort with a rich history and well-preserved natural areas. The narrow Kerchinsky Strait allows ships access to the little gulf called the Sea of Azov, where the port of Taganrog is located. Access to the sea from the Mediterranean is controlled by Turkey.
In the Baltic Sea, the Curonian Spit is the longest sandbar feature in Europe. It is also an international nature park shared by Russia and Lithuania. The Gulf of Finland allows sea access to Europe from St. Petersburg—the main reason why Peter the Great built the city there after winning control over that territory from Sweden in the early 1700s. The port of St. Petersburg is now protected by an artificial dam stretching across the gulf 20 km offshore. It eases severe spring floods, but traps water pollutants.
The Kola Peninsula, in the Arctic portion of European Russia, contains important metal and phosphate deposits and separates the White Sea from the ocean. The Kanin Nos, Yamal, and Taymyr Peninsulas are prominent farther east. The Karskie Vorota Strait (33 km wide) in the eastern Barents Sea separates the southern island of Novaya Zemlya from the island of Vaigach. This is usually the impassable gate to the Arctic Ocean beyond, where ice melts only in July and August. When nuclear icebreakers are used, navigation through it is possible for about 4 months of the year. With global warming continuing to accelerate, it is likely that much of the so-called Great Northern Seaway Route will become navigable year-round by the end of the 21st century. The distance from Europe to Japan via the Suez Canal is about 12,000 miles, whereas it is only about 6,000 miles via the Northern Seaway.
Four main archipelagos exist in the Russian Arctic: Novaya (New) Zemlya and Franz Joseph Land in the European sector, and Severnaya (Northern) Zemlya and the Novosibirskie Islands in the Asian sector. The solitary Wrangel Island is an important wildlife area and a preserve in the easternmost corner of the Russian Arctic. The Bering Strait (90 km wide) separates Eurasia from North America, and Russia from the United States. Technically, the closest the two countries come together is between Ratmanov (Russia) and Kruzenstern (U.S.) in the Diomede Islands, a distance of just 4 km! There have been proposals to build an underwater railroad tunnel to connect the two continents. It would be about twice as long as the Channel Tunnel between England and France.
In the Russian Pacific, Chukchi and Kamchatka (peninsulas) and Sakhalin and the Kurils (islands) are important features. Kamchatka has the highest concentration of volcanoes in Russia, with over 30 being active. Chukotka, Sakhalin, and the Kurils have strategic importance as fishing areas and for military reasons. About 20 large and 30 small Kuril Islands stretch for over 1,000 km from the tip of Kamchatka to Hokkaido. Japan still claims four of the southernmost Kurils as its own; they were taken over by the U.S.S.R. after World War II as a form of compensation for the damage caused by Japan as the aggressor. Although these islands themselves are not large or mineral-rich, the lucrative exclusive economic fishing zone of 200 miles around them and the opportunity of placing antimissile radar installations on them make the Kurils a prized possession for Russia, so it is highly unlikely that they will be handed back to Japan any time soon. An estimate from the Yeltsin period pegged their worth at $100 billion in U.S. dollars—a considerably heftier sum than the $7.2 million Russia wanted for Alaska in 1867, even after adjustment for inflation.
The Impact of Northern Eurasia’s Relief on Humans
The overall impact of relief on human life in Northern Eurasia is not as significant as in many other parts of the world, because the region is flat in most places. The largest plains, the Eastern European Plain and the Western Siberian Lowland, allowed early settlers easy travel along meandering rivers, such as the Dnieper, the Don, the Volga, the Northern Dvina, and the Pechora in the European part, and the Ob–Irtysh system in western Siberia. In the central part of Siberia, despite the presence of a large elevated plateau, relatively easy travel along the Yenisei and Lena was likewise possible. Plenty of land has been available for human settlement on easily accessible, flat terrain.
Only in the southern mountain belt does relief present some challenges to human travel and settlement. The jagged relief of the Caucasus and the Pamirs in particular, and the sheer size of these mountains, preclude easy travel across the ranges even today: there is only one year-round paved highway from Russia into Georgia across the main Caucasus range, for example. The most dangerous road in the U.S.S.R. as measured by accidents was the Khorog-Osh highway, in the remote parts of the Pamirs in eastern Tajikistan.
Relief may thus have played a role in producing cultures: Deep gorges separated by inaccessible mountain ranges made the Caucasus one of the most linguistically diverse areas on earth, as each group formed in relative isolation from others. Over 20 languages are recognized in just one part of the Caucasus, Dagestan. Furthermore, mountains provided a natural defense barrier against the invaders, and thus the Caucasus and mountainous Tajikistan were the last two areas added to the growing Russian Empire. The boundary between Tajikistan and Kyrgyzstan passes through some of the highest terrain on earth, and is therefore a natural as well as a political border.