how do lakes form?

Answer 1

Lakes can be formed by tectonic movements, glaciers, volcanic activity, dissolution of bedrock, erosion and deposition of rivers, and meteorites.

Limnology is the study of the physical, chemical, biological, and meteorological conditions in lakes. Limnology covers lakes, ponds, reservoirs, streams, rivers, wetlands, and estuaries, while oceanography covers the open sea.

The processes in lake formation are:

1. Constructive
2. Destructive
3. Obstructive

Natural lakes can form by various processes. Although many of these processes occurred in the geologic past, lakes continue to form and to be destroyed. For example, an earthquake-triggered landslide created Lake Sarez in Tajikistan only three generations ago. In May 1980, Spirit Lake at the foot of Mount Saint Helene, Washington (USA) was greatly reduced in size when the volcano erupted, pouring rock, mud, and debris into the one-popular resort lake.

TECTONIC ACTIVITY

Many lakes have formed as a result of tectonic movements of the Earth's crust. Lake Baikal, located in eastern Russia, formed in the Baikal Rift of the Siberian Platform. Lakes Tanganyika, Malawi (formerly Nyasa), Kivu, Turkana, Mobutu, Magadi, Naivasha, and Natron lay along the East African Rift Valley. Other crustal movements influencing lake formation include uplift of the seafloor (Caspian Sea and Aral Sea), and uplift around a central basin (Lake Victoria).

The Basin and Range Province of the western United States contains tectonic lakes in the valleys between fault-block mountains (Lake Tahoe, California-Nevada border). Many Basin and Range lakes are remnants of larger lakes that existed 10,000 to 30,000 years ago, during the Pleistocene epoch (Ice Age). The Great Salt Lake, which covers 2,500 to 6,000 square kilometers (960 to 2,300 square miles) and is about 10 meters (33 feet) deep, is a remnant of Pleistocene Lake Bonneville, which covered 50,000 square kilometers (19,300 square miles) and was 300 meters (980 feet) deep.

GLACIERS

Glaciers formed lake basins by gouging holes in loose soil or soft bedrock, depositing material across stream beds, or leaving buried chunks of ice that later melted to leave lake basins (Figure 1). When these natural depressions or impoundments filled with water, they became lakes. After the glaciers retreated, sediments accumulated in the deeper parts of the lake. These sediments entered the lakes from tributaries and from decomposed organic material derived from both the watershed and aquatic from plants and algae.

Lakes tend to be largest and most abundant in high latitude areas in the Northern Hemisphere that were occupied by glaciers during the Pleistocene epoch. Glaciers are large bodies of ice that form on land as a result of the accumulation and compaction of snow. As glaciers slowly move under the influence of gravity, they erode the landscape, leaving deep basins and valleys. The largest glacial lakes are the Great Lakes of North America (Superior, Huron, Michigan, Erie, and Ontario), and also Canada's Great Slave and Great Bear Lakes.

Deposits of eroded glacial debris may disrupt drainage patterns. In the Alps of Europe, Lakes Geneva, Lucerne, Zurich, and Constance formed by glacial sediment damming valleys carved by glaciers. New York state's Finger Lakes formed by glacial sediment damming rivers and streams. Kettle lakes, common in the Midwest, formed as ice blocks melted in-place within glacial sediment.

Volcanic Activity

Lakes formed by volcanic activity tend to be relatively small. Lakes may form within the crater of an active but quiet volcano, in a caldera produced by explosion and collapse of an underground magma chamber (Crater Lake, Oregon), on collapsed lava flows (Yellowstone Lake, Wyoming), and in valleys dammed by volcanic deposits (Sea of Galilee, Israel).

Other Natural Processes

Many other types of lakes exist. In areas under-lain by soluble rock such as limestone, lakes may occupy sinkholes formed by dissolution of the bedrock. Dissolution lakes are common in Florida, as well as in Puerto Rico and in the former Yugoslavia, which are areas underlain largely by limestone.

Erosion and deposition of rivers can form lakes, such as meandering rivers forming oxbow lakes. Some lakes are associated with levees on river deltas (Lake Pontchartrain, Louisiana). Lakes can form where landslides dam stream valleys. Wind action can form lakes, including deflation basin lakes formed by wind erosion (northern Texas, New Mexico, parts of Australia), and lakes in low areas between sand dunes (Sand Hills, Nebraska). Lakes may form along the coastline, where sediment deposition isolates an embayment (Coorong lakes, southeastern Australia).

Meteorite impacts can form lakes (Lake Bosumtwi, Ghana; and Manicouagan Lake and Chubb Lake, Quebec). The origin of some lakes is unresolved, but much debated, such as the ellipsoidal "Carolina bays" on the coastal plain of the southeastern United States.

Answer 2

How Are Lakes Formed

Answer 3

Ox bow lakes are formed in the following way 1. The river meanders in its valley 2. When the river floods it has enough energy to erode a new channel across the meander 3. The old meander is spearated from the river and is left as an ox-bow lake 4. In time the lake will evaporate or silt up I don't know how the heck you're going to get 7 marks for it but I'd draw a diagram explaining it aswell as the writing! Ive got a Geography exam on Monday! ahhh, If you need any more help you just just help with studying feel free to e-mail me! :)

Answer 4

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An ox bow lake is formed from a meander of a river that was cut off during a flood. Due to erosion, the meander edges of a river can approach quite closely. During normal flow, the water will simply follow the meander. During flood times, however, the water will move more quickly and with more force. This extra force can cause the water to take a shortcut over the land between the close points of the meander. If th eflood is brief, minimal damage will be done to the land, and the river will resume normal flow afterwards. If the flood takes longer, or if there was a huge mass of water, the land between the meander corners will be eroded or swept away. Once the floods subside, if deposition occurs at the points of the original meander, a horseshoe-shaped lake will remain: the remnants of the original meander.

Answer 5

Some by dams, natural or man made, at a point in a river which then fills behind the dam. Others were made long ago as glaciers moved across the land creating dips and valleys that eventually filled with water.

I'm sure there are other ways as well.

Answer 6

lakes are cool

Answer 7

From meteors or craters