Examples include glacial moraines, eskers, and kames. The consequent surface glacial deposits include gravels as outwash and moraines. Kettle lakes may be formed within the ground moraine region behind the terminal moraines. There are many signs of glaciers including kames, eskers, kettles, and moraines. The steep hills surrounding these lakes are filled with loose shale from glacial moraines. Drumlins and ribbed moraines are also landforms left behind by retreating glaciers. Second, global warming has led to the formation of glacial lakes dammed by unstable moraines. A series of parallel ridges resemble moraines dropped by glaciers. The end moraines of different glacial retreats have been conserved. In addition moraines have been left behind by various glacial periods. Glaciers carved out the valleys during the late Pleistocene, which left a number of moraines. Such initial stages of soil development have been described on volcanoes, inselbergs, and glacial moraines. In alpine glaciers, ground moraines are often found between the two lateral moraines. Multiple lateral moraines may develop as the glacier advances and retreats. Terminal moraines mark the maximum advance of the glacier.