Moses Coulee glaciation on the Waterville Plateau includes polished and striated bedrock, glacial erratics, drumlinoid topography, eskers, moraines, meltwater channels, and glacial till. The Withrow Moraine complex marks the maximum southern extent of the Okanogan Lobe, and a series of recessional moraine complexes represent retreating ice margins. Ice damming of the Columbia River formed Glacial Lake Columbia and Lake Spokane, larger lakes than Lake Roosevelt, which is currently backed up in the same location behind the Grand Coulee Dam. A precursor to glacial-flood-cut Moses Coulee existed prior to the glacial floods as a drainage basin with a number of side streams, draining
Battle of Birch Coulee side of the Minnesota River with a force of 350 Indians. Gray Bird's party and Brown's troops missed encountering each other during the day, but some Indian scouts discovered that Brown's troops were moving toward the campsite at Birch Coulee. The Sioux planned to ambush Brown's troops in the morning, thinking that only the cavalry was present and that they could be easily destroyed. The Birch Coulee campsite was not easily defensible, since the Indians could approach from all sides and still remain under cover. Also, since the burial detail felt themselves safe, they did not take precautions against attack