A cryptodepression is a depression in the Earth's surface that is below

mean sea level There are several kinds of mean in mathematics, especially in statistics. Each mean serves to summarize a given group of data, often to better understand the overall value ( magnitude and sign) of a given data set. For a data set, the '' ...

, and which is filled by a lake. The term is derived from the

Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic pe ...

word ('hidden') and depression.

Description

A cryptodepression is often due to creation of a

rift valley A rift valley is a linear shaped lowland between several highlands or mountain ranges created by the action of a geologic rift. Rifts are formed as a result of the pulling apart of the lithosphere due to extensional tectonics. The linear d ...

or a

glacial lake A glacial lake is a body of water with origins from glacier activity. They are formed when a glacier erodes the land and then melts, filling the depression created by the glacier. Formation Near the end of the last glacial period, roughly 10, ...

. Lakes are often long and narrow. Further, the surrounding landscape and the shore of the lake can be very steep.

Examples

Simple calculation example: Lago O'Higgins/San Martín Surface elevation 250 m - Maximal depth 836 m = _________________________________ Cryptodepression -586 m * ''Glacial lakes and moraine-dammed lakes'': major prealpine lakes in Italy have cryptodepressions created by

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...

. In other parts of the

Alps The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Sw ...

, Swiss, Bavarian and Austrian lakes, cryptodepressions are not found because the lakes have significantly higher elevations. Glacial lakes creating cryptodepressions also occur in Norway, Chile, Argentina, Newfoundland, New Zealand, and Scotland. In North America, four of the five

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...

(all except Erie) and two of the Finger Lakes in New York,

Cayuga Lake Cayuga Lake (,,) is the longest of central New York's glacial Finger Lakes, and is the second largest in surface area (marginally smaller than Seneca Lake) and second largest in volume. It is just under long. Its average width is , and it is ...

and Seneca Lake, are examples of cryptodepressions.

Mälaren Mälaren ( , , or ), historically referred to as Lake Malar in English, is the third-largest freshwater lake in Sweden (after Vänern and Vättern). Its area is 1,140 km2 and its greatest depth is 64 m. Mälaren spans 120 kilometers from e ...

in Sweden was created by a different process; it had been an arm of the Baltic Sea as recently as the

Viking Age The Viking Age () was the period during the Middle Ages when Norsemen known as Vikings undertook large-scale raiding, colonizing, conquest, and trading throughout Europe and reached North America. It followed the Migration Period and the Germ ...

before being cut off from the sea by post-glacial rebound. * ''Rift valleys'': the deepest known cryptodepression on Earth is in

Lake Baikal Lake Baikal (, russian: Oзеро Байкал, Ozero Baykal ); mn, Байгал нуур, Baigal nuur) is a rift lake in Russia. It is situated in southern Siberia, between the federal subjects of Irkutsk Oblast to the northwest and the ...

(-1200 m). Other notable examples include

Lake Tanganyika Lake Tanganyika () is an African Great Lake. It is the second-oldest freshwater lake in the world, the second-largest by volume, and the second-deepest, in all cases after Lake Baikal in Siberia. It is the world's longest freshwater lake. T ...

and

Lake Malawi Lake Malawi, also known as Lake Nyasa in Tanzania and Lago Niassa in Mozambique, is an African Great Lake and the southernmost lake in the East African Rift system, located between Malawi, Mozambique and Tanzania. It is the fifth largest f ...

in Africa's

East African Rift The East African Rift (EAR) or East African Rift System (EARS) is an active continental rift zone in East Africa. The EAR began developing around the onset of the Miocene, 22–25 million years ago. In the past it was considered to be part of ...

References

{{geomorph-stub Depressions (geology) de:Depression (Geologie)