Unit 6. «Lakes» Exercises (a)

1. Learn new words:

source – источник pond – пруд

feel into – питать glacial origin – ледниковое

stream – поток, течение происхождение

spring – родник destruction – разрушение

arid – сухой, засушливый to dam up – запруживать

saline – соленый humid – сырой

Dea Sea – Мертвое море depth – глубина

volcanic activity – вулканическая to prevent – предотвращать

активность runoff – сток

permanent – постоянный

ephemeral – переходящий

way – путь, способ

faulting – ошибочный прорыв,

разрыв в слове

crust – кора

crater – кратер

1. Translate the following word combinations:

а sizeable inland body; the source of the water; to fall into the lake; as rain or snow; by streams and springs; lakes without outlets; in arid regions; to be saline; result from weathering and volcanic activity; the concentration of salts; due to evaporation; some saline lakes; can be permanent or ephemeral; in cold regions; may be perennially frozen; faulting and gentle upwarping of the Earth's crust; to be responsible for some of the greatest lakes; upwarping formed Lake Victoria in Africa; the Caspian and Aral seas in Asia; to be formed by volcanic activity; to occupy craters and calderas; landslides form lakes by damming up valleys; especially in mountainous regions; lakes of glacial origin; to be far more numerous than all other types;

to be located in glacially-formed bedrock basins; from the irregular deposition of till; ponds and small lakes; to extend below the water table; in many different ways; to occupy abandoned channels on floodplains; short-lived geological features; in humid regions; deposition of detrital sediments and of organic matter; to fill the basin; in arid regions; the exposition of chemical precipitates and sediments; to reduces the size of the lake.

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Text (a)

Read the text «Lake»

Lake is а sizeable inland body of standing water. The source of the water is precipitation that falls into the lake as rain or snow, or is fed into it by streams and springs. Lakes without outlets are usually found in arid regions and tend to be saline; some, such as Great Salt I.ake and the Dead Sea, are more salty than an ocean. The salts in most saline lakes result from weathering and volcanic activity; they were carried into the lakes by water and wind, usually when the lakes were larger. The concentration of salts is due to evaporation. Some saline lakes, like the Caspian and Агаl seas, are landlocked arms of the ocean. Lakes can be permanent or ephemeral, and those in cold regions may be perennially frozen.

Lakes are formed in many ways. Faulting and gentle upwarping of the Earth's crust are responsible for some of the greatest lakes. Faulting produced those of the African Rift Уа11еу and of south-western United States. Upwarping formed Lake Victoria in Africa, and the Caspian and Aral seas in Asia. Lakes are also formed by volcanic activity, they occupy craters and calderas (as in Crater Lake, Oregon) and occur where lava flows and volcanoes obstruct drainage. Landslides form lakes by damming up valleys, especially in mountainous regions. А lake 70 km long and over 200 m deep was formed in 1840 when а landslide blocked the Indus River, Kashmir.

Lakes of glacial origin are far more numerous than all other types put together. Some are dammed by ice, as in Greenland and in other regions now glaciated. Many are located in glacially-formed bedrock basins. Others result from the irregular deposition of till. Ponds and small lakes occur where kettle holes extend below the water table, as on Саре Cod, Mass. Rivers form lakes in many different ways, as, for example, the oxbow lakes that occupy abandoned channels on floodplains or the lakes found on deltas.

Lakes are short-lived geological features: their destruction commences as soon as they are formed. In humid regions the outlet stream lowers the barrier, and the deposition of detrital sediments and of organic matter helps fill the basin. In arid regions the Exposition of chemical precipitates and sediments borne by wind and stremas help fill the basin, and evaporation reduces the size of the lake.