What is "earth lodge"

An earth lodge is a semi-subterranean building covered partially or completely with earth, best known from the Native American cultures of the Great Plains and Eastern Woodlands. Most earth lodges are circular in construction with a dome-like roof, often with a central or slightly offset smoke hole at the apex of the dome. Earth lodges are well-known from the more-sedentary tribes of the Plains such as the Hidatsa, Mandan, and Arikara, but they have also been identified archaeologically among sites of the Mississippian culture in the eastern United States.