'Small sweat lodges were often made of mud and covered with mats and tree branches. Larger sweat lodges might be made of logs. In one kind of sweat lodge, the entrance was sealed from the outside and then someone poured water over hot rocks that had been placed on the floor [ground?]. This created steam, which caused the people in the sweat lodge to perspire. Sweat lodge ceremonies were designed to purify the body, cure illnesses, and influence spirits. Most sweat lodges were built near rivers so the people using them could jump into cool water after leaving the lodge.'


quoted from
Indians of the Northwest Coast and Plateau
World Book
a Scott Fetzer company
Chicago