Overdeepening in the context of "Cirque (landform)"

The Finger Lakes are a group of eleven long, narrow, roughly north–south lakes located in an area called the Finger Lakes region in New York, in the United States. This region straddles the northern and transitional edge of the Northern Allegheny Plateau, known as the Finger Lakes Uplands and Gorges ecoregion, and the Ontario Lowlands ecoregion of the Great Lakes Lowlands.

The geological term finger lake refers to a long, narrow lake in an overdeepened glacial valley, while the proper name Finger Lakes goes back to the late 19th century. Cayuga and Seneca Lakes are among the deepest in the United States, measuring 435 and 618 feet (133 and 188 m), respectively, with bottoms well below sea level. Though none of the lakes' widths exceed 3.5 miles (5.6 km), Seneca Lake is 38.1 miles (61.3 km) long, and at 66.9 square miles (173 km) is the largest in total area.

A cirque (French: [siʁk]; from the Latin word circus) is an amphitheatre-like valley formed by glacial erosion. Alternative names for this landform are corrie (from Scottish Gaelic: coire, meaning a pot or cauldron) and cwm (Welsh for 'valley'; pronounced [kʊm]). A cirque may also be a similarly shaped landform arising from fluvial erosion.

The concave shape of a glacial cirque is open on the downhill side, while the cupped section is generally steep. Cliff-like slopes, down which ice and glaciated debris combine and converge, form the three or more higher sides. The floor of the cirque ends up bowl-shaped, as it is the complex convergence zone of combining ice flows from multiple directions and their accompanying rock burdens. Hence, it experiences somewhat greater erosion forces and is most often overdeepened below the level of the cirque's low-side outlet (stage) and its down-slope (backstage) valley. If the cirque is subject to seasonal melting, the floor of the cirque most often forms a tarn (small lake) behind a dam, which marks the downstream limit of the glacial overdeepening. The dam itself can be composed of moraine, glacial till, or a lip of the underlying bedrock.

A finger lake, also known as a fjord lake or trough lake, is "a narrow linear body of water occupying a glacially overdeepened valley and sometimes impounded by a morainic dam." Where one end of a finger lake is drowned by the sea, it becomes a fjord or sea-loch.