Glacial Lake Missoula and Its Humongous Flood: And Its Humongous Floods [ペーパーバック]

This book is an extremely interesting study of the gigantic cataclysms caused when the ice dam holding back impounded glacier-melt waters in western Montana's Lake Missoula would periodically burst. The consequent outrushes repeatedly resculpted lands in northern Idaho, and eastern and central Washington, resulting in the curious, almost eerie, landforms covering much of that area today. Excellent photography amply demonstrates these effects.

Dr. Alt is a good writer, whose text carves a continuous, easily-followed thread that brings to life the events surrounding these floods, and their effects. His enthusiasm is contagious.

This book should not be read alone, but in conjuction with the book, "Cataclysms on the Columbia", written earlier. Any tourist going to the Northwest, and certainly natives of that wonderful region, will enjoy both books, and gain a valuable, lasting impression of this most peculiar part of the Earth. Each book will give directions to the most spectacular phenomena as well. I highly recommend each, but again suggest both should be read in conjunction.

My knowledge of geology is so incomplete that I don't even qualify as an amateur. However, I live in Missoula, Montana, and from my window can see beach lines left by the several fillings of Lake Missoula. I have listened to David Alt, the author of this book, describe the geologic events of ten to fifteen thousand years ago. In geologic time, that is very recent. Possibly the lake and floods were seen by humans. What a sight that would have been!

My wife and I have carried this book, and the roadside geology books written or coauthored by David Alt, as we drove through Montana, Idaho, Washington, and Oregon. These are the four states involved in the lake and floods. We have compared the many photos and sketches of the book with the actual physical features. Until recently, these books were the only sources of information written in layman's language.

In a nutshell, a huge lake formed behind a dam of glacial ice at the border of Idaho and Montana. It was 2000 feet deep at the dam, 900 feet deep at Missoula, and stretched more than a hundred miles up several valleys. The dam washed out and in less than a week, there were huge floods across Washington and out the Columbia River Gorge to the Pacific. Flood waters backed far up river valleys such as the Yakima and the Willamette. The dam reformed and the event was repeated forty times or more. The floods left behind physical features that match the scope of the event. There are huge silt deposits, giant ripple marks, enormous erratic boulders moved hundreds of miles, and immense rock surfaces scoured by the flooding waters. The great valleys and waterfalls left behind now stand dry. This book tells all; or at least as much as geologists understood in 2001 when the book was published.

A fascinating side story found in the book is about J. Harlen Bretz, the redoubtable geologist who correctly interpreted the evidence of the flood and fought the geologic world to a standstill. He was booed when presenting his theories in national geologic meetings. However, he lived to see most of his detractors either change their viewpoints or go to their graves unconvinced. Today, there is an organization that has gotten Congressional approval to establish an informative "trail" through the four states. It would inform travelers about the geology. There are already signs along the roads and displays in museums. Much of the success is attributable to David Alt and his book "Glacial Lake Missoula and Its Humongous Floods."

If the idea of catastrophic glacial floods and their still-visible effects on vast reaches of Eastern Washington's geology and topography fascinates you, I haven't found a better book for building a perspective of the whole process.

This is particularly true if you are not a trained geologist: Mr. Alt lays a foundation that illustrates the conditions that led to the mega-floods, then follows the evidence that the floodwaters left upon various watercourses on their way to the ocean.

Mr. Alt presents it all in terms a layperson can understand and use in exploring a series of disasters writ large upon the land.