Meanwhile, Clark and his group came down into the lands of the Crow people by the Beaver River.
On July 21 the party woke up to find that half their horses had been stolen, although they never saw any Crow.
They went down the Yellowstone towards the Missouri and stopped at a natural pillar of rock (close to modern Billings, MT). Clark scratched his signature in the pillar alongside petroglyphs of native peoples. He also named it 'Pompey's Tower' (later renamed 'Pillar') after the son of the party's Native American Sacagawea.
