Grand Coulee Grand Coulee The Grand Coulee is an ancient river bed in the U.S. state of Washington. This National Natural Landmark stretches for about 60 miles (100 km) southwest from Grand Coulee Dam to Soap Lake, being bisected by Dry Falls into the Upper and Lower Grand Coulee. The Grand Coulee is part of the Columbia River Plateau. This area has underlying granite bedrock, formed deep in the Earth's crust 40 to 60 million years ago. The land periodically uplifted and subsided over millions of years giving rise to some small mountains and, eventually, an inland sea. From about 10 to
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