Beginning over a million years ago, at least seven enormous lava flows spread across eastern Washington State from northern Idaho, laying down layers which are up to 10,000 feet in thickness and extend over 30,000 square miles. Between these basalt layers are sedimentary rock and layers of gravel containing vegetative remains and erosion debris deposited by ancient rivers and lakes. These are often exposed in canyon walls in Klickitat County. The flows of lava from great fissures are so uniform in thickness and so extensive they must have spread like water to cover such vast distances. The cooling of these thick flows took many years and resulted in extensive fracturing which shows clearly in the basalt cliffs near the Columbia River.

More recent mountains resulted from folding of the earth's crust. Some of this is thought to have occurred during the Ice Age which ended about 11,000 years ago. As a result of the ice sheet in northeastern Washington, gigantic ice dams formed and created a 3000-square mile lake which extended 250 miles to the east. The ice sheet itself did not come as far south as Klickitat County. When the climate warmed up and these ice dams melted, great floods occurred across central Washington, carving out the Columbia River Gorge and smaller canyons, falls and coulees. The flood crest was about 1200 feet.

Water poured down the Columbia, widening the river valley and cleaning off all soil up to elevations of 1000 feet as far as The Dalles. Boulders were carried along, frozen in icebergs, and deposited in tributary valleys. The evidence of such a flood is all around us and can be regarded as one of the most powerful events of the earth's past. It seems certain that part of southeastern Klickitat County was inundated at that time. Much of the county was untouched by flood waters north of the Columbia Hills.

The Cascade Mountains are the newest mountain range in the United States. They were formed largely by volcanic action and run north-south through Oregon and Washington, broken only by the Columbia River Gorge. The west end of Klickitat County lies on the eastern slope of these great mountains. The Columbia River begins several hundred miles north in the Canadian Rockies, meanders south through Washington, then makes a right angle turn near the Tri-Cities and heads west to the Pacific Ocean. Klickitat County lies on the north bank of the river and has a shoreline 84 miles long.