The Belt Supergroup represents one of the thickest sections of Precambrian sedimentary rocks in world. It contains rare features, such as molar-tooth structures, syneresis cracks, and "stromatolites." The rocks were deposited in an intracratonic basin thought to be at least 25 km deep, which could have originated as an impact crater. It is conventionally dated as Mesoproterozoic, about 1.4 Ga. Correlation of formations across the Belt Basin is difficult. The sediment originated predominantly from the west, but since there is no obvious source to the west today, there is much speculation on the land mass that once existed to the west. The place of the Belt Supergroup within Biblical Earth history points to the Flood, especially given the generally conformable contact between the Belt rocks and the overlying Cambrian Flathead Sandstone, a universally accepted Flood rock. Thus, the Belt rocks likely were deposited very early in the Flood. Some of the Belt rocks imply tremendous catastrophism very early in the Flood.