Basins from crustal movement
Tectonic lakes such as the Caspian Sea, the Sea of Aral and the Central African Rift lakes occupy basins formed by movement of the Earth's crust. Lake Baikal sits in a rift valley and reaches 1,637 metres.
Kinds, depths and leaders
Lakes form by tectonic movement, glaciation, volcanism and river action, and each mechanism leaves a different basin behind. This reference sets out the formation types, the leader lakes by depth, area and volume, and the national counts that make lake statistics comparable.
01
A lake's mechanism decides the shape and depth of its basin. Tectonic rifting produces the deepest lakes; glaciation produces the densest clusters; volcanism and river cutoffs produce smaller, distinctive basins.
02
Depth, area and volume are separate records, and Lake Baikal holds two of them while Lake Superior holds the third. Reading a record without its measure is the most common error in lake comparisons.
03
National lake totals are only comparable when the counting rule is stated. Canada's 31,752 lakes over 3 square kilometres and Finland's 168,000 lakes over 500 square metres describe different thresholds, and both totals sit alongside a much larger count of smaller basins.
Lakes are grouped by the mechanism that carved or filled their basins, and the main groups are tectonic, glacial, volcanic and river-made.
Tectonic lakes occupy basins formed by movement of the Earth's crust. The Caspian Sea, the Sea of Aral and the lakes of the Central African Rift are tectonic basins; Lake Baikal sits in a rift valley and is the deepest lake in the world, with its bottom at 1,637 metres.
Glacial lakes fill scoured hollows left by retreating ice sheets and moraine dams. Volcanic lakes fill craters or calderas, or sit behind lava dams. Oxbow lakes form when a river meander is cut off from the main channel. Each mechanism produces a characteristic shape and depth profile.
Most lakes are freshwater, and most lie in the Northern Hemisphere at higher latitudes, where glaciation has left the densest concentration of basins.
Tectonic lakes such as the Caspian Sea, the Sea of Aral and the Central African Rift lakes occupy basins formed by movement of the Earth's crust. Lake Baikal sits in a rift valley and reaches 1,637 metres.
Glacial lakes fill hollows left by retreating ice sheets and basins dammed by moraines. This mechanism accounts for the dense concentration of lakes at higher northern latitudes.
Volcanic lakes fill craters or calderas, or sit behind lava dams. Their basins are among the most regular in outline of any lake type.
An oxbow lake forms when a river meander is cut off from the main channel. The basin keeps the curve of the original bend and is typically shallow.
A meromictic lake has layers of water of different temperature and density that do not intermix, and its deepest layer contains no dissolved oxygen. The condition is an exception, not the rule.
Lake Baikal leads on depth at 1,637 metres and on freshwater volume at 23,600 cubic kilometres. Lake Superior leads on surface area at 82,100 square kilometres.
Depth, area and volume are separate records: a lake can lead on one measure and not on the others.
| Lake | Measure | Value | Note |
|---|---|---|---|
| Lake Baikal | Maximum depth | 1,637 m | Deepest lake in the world |
| Lake Baikal | Mean depth | 749 m | Greatest mean depth in the world |
| Lake Baikal | Freshwater volume | 23,600 km³ | World's largest freshwater lake by volume |
| Lake Superior | Surface area | 82,100 km² | Largest surface area among the world's great lakes |
| Caspian Sea | Basin type | Tectonic | Basin formed by movement of the Earth's crust |
| Central African Rift lakes | Basin type | Tectonic | Rift-valley lakes of the Central African Rift |
| Canada | Lakes over 3 km² | 31,752 | Total number of lakes estimated at least 2 million |
| Finland | Lakes of 500 m² or more | 168,000 | Counting rule sets the threshold at 500 square metres |
Figures on this page are drawn from standard reference measurements of lake depth, area, volume and national lake counts.