Withrow Moraine and Jameson Lake Drumlin Field erosion resulting from the Missoula Floods, which laid bare many layers of the basalt flows on the edges of the plateau at Grand Coulee and Moses Coulee. Two million years ago the Pleistocene epoch began and Ice age glaciers invaded the area. They scoured the Columbia River Plateau, reaching as far south as the middle of the Waterville Plateau highlands above the Grand Coulee and south to the head of Moses Coulee. In some areas north of the Grand Coulee they were as much as 3 km (10000 feet) thick. Grooves in the exposed granite bedrock are still visible in
Coulee City, Washington males. The median income for a household in the town was $25,938, and the median income for a family was $42,500. Males had a median income of $31,375 versus $17,250 for females. The per capita income for the town was $14,411. About 14.9% of families and 22.1% of the population were below the poverty line, including 29.2% of those under age 18 and 11.7% of those age 65 or over. Coulee City, Washington Coulee City is a town in Grant County, Washington. The population was 562 at the 2010 census. The town was named after nearby Grand Coulee. Coulee City