Glacial Lake Missoula and Its Humongous Floods tells the tale of a huge Ice Age Lake that, when it suddenly drained, unleashed more then ten times the combined flow of all the modern rivers of the world. The book follows the path of the floodwaters as they raged from western montana across the Idaho Panhandle, then scoured eastern Washington and rushed down the Columbia Gorge to the Pacific Ocean.
Until about 200 million years ago, the western margin of North America lay to the east, along the present Idaho border, and a broad coastal plain spread westward into Oregon. The rest of the state was ocean floor. Then the continent began moving slowly westward away from Europe and the floor of the Pacific Ocean began sliding beneath the western edge. That is what created Oregon, and this book tells how it happened.
The geology of Washington is a story of islands-- micro-continents-- coming in from the sea. Two hundred million years ago most of Washington consisted of two large islands, each one a scrap of continent, lying somewhere in the vastness of the Pacific Ocean. One after the other they docked onto the North American continent, each adding its distinctive bit to the complex geologic and geographic mosaic of western North America.