Glacial activity about 9000 to 12000 years ago created this lake from what had previously been a river valley. An ice sheet occupied major valleys north of here, and as the glacier receded, meltwaters flooded across the outlet of this valley beyond modern Coeur d'Alene. Rock, sand, and gravel deposited there by those floods raised the level of the land and blocked the old river channel, backing up the river, submerging the valley, and producing one of Idaho's lovely views.