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 the reservoir is reserved for tribal hunting and boating. Built in the late 1970s, the Visitor Center contains many historical photos, geological samples, turbine and dam models, and a theater. The building was designed by Marcel Breuer, and resembles a generator rotor. Since , on summer evenings, the laser light show at Grand Coulee Dam is projected onto the dam's wall. The show includes full-size images of battleships and the Statue of Liberty, as well as some environmental comments. Tours of the Third Powerplant are available to the public and last about an hour. Visitors take a shuttle to view