Geology of the Pacific Northwest along their course. The larger cataract was that of the upper Grand Coulee, where the river roared over an waterfall. The eroding power of the water plucked pieces of basalt from the precipice, causing the falls to retreat and self-destruct by cutting through to the Columbia River valley near what is now the Grand Coulee Dam. The other major cataract is now known as Dry Falls. It started near Soap Lake in Washington State, where less resistant basalt layers gave way before the great erosive power of this tremendous torrent and waterfalls developed. As in the upper Grand Coulee, the
Grand Coulee Dam Wenatchee. Together, they became known as the "Dam College". Woods began promoting the Grand Coulee Dam in his newspaper, often with articles written by O'Sullivan. The dam idea gained popularity with the public in 1918. Backers of reclamation in Central Washington split into two camps. The "pumpers" favored a dam with pumps to elevate water from the river into the Grand Coulee from which canals and pipes could irrigate farmland. The "ditchers" favored diverting water from northeast Washington's Pend Oreille River via a gravity canal to irrigate farmland in Central and Eastern Washington. Many locals such as Woods, O'Sullivan and