I learned a new word today: bajada.
bajada: [buh-ha-duh]: a plain formed at the base of a mountain by the merging of several alluvial fans.
A whole bunch of rivers and streams fly down a mountain carrying all sorts of dirt, rock, and debris with them along the way, and all that crap gets dumped at the bottom when the rivers slow down. After a few thousand years or so, it all builds up into a pile so big that it becomes it's own landform spread out over miles at the mountain's base.
That's so cool.