This contributed to the formation of large pluvial lakes in Nevada. The formation dates to the Carnian Pluvial Event. For example, some have used the term "Riss pluvial" in Egyptian contexts. Pluvial lakes also formed during this time. These marshes lie in the desiccated lake bed of a Pleistocene age pluvial lake. This isolation dates back to the last Pleistocene Pluvial period about 12,000 years ago. Pluvial lakes are typically closed lakes that occupied endorheic basins. Pluvial lakes were most extensive during glacial periods. Pluvial lakes are also common across the state. Mud Lake and Harney Lake are also remnants of the original pluvial lake. Also notably, there was a heightened rate of extinction during the Carnian Pluvial Event. Simple regimes can be nival, pluvial or glacial, depending on the origin of the water. It has the pluvial regime and often dries up in summer. A pluvial is a warmer period of increased rainfall; an interpluvial, of decreased rainfall. Lake Lahontan was a large Pleistocene pluvial lake that covered much of western Nevada.