Places where groundwater percolates to the surface too slowly to be considered a spring are seeps. Water oozes out of the ground rather than ﬂows. The soil around the seep is seasonally or perpetually wet, and enough water may collect to form a pool or an area of wetland. This term also applies to places where petroleum rises naturally to the surface, such as the asphalt seeps in Los Angeles known as the La Brea Tar Pits. Material collected from oil seeps in various parts of the continent were used by Native Americans to waterproof baskets and canoes and as medicine.