Answer:
The indigenous peoples of the Americas arrived in North America via the Bering Strait land bridge, which existed approximately 15,000 years ago between Siberia and Alaska, and probably also via a succession of sea migrations from Asia.
C) gravity because gravity compresses the start into the most compact shape possible
Often, waterfalls form as streams flow from soft rock to hard rock. This happens both laterally (as a stream flows across the earth) and vertically (as the stream drops in a waterfall). In both cases, the soft rock erodes, leaving a hard ledge over which the stream falls
