The Grand Coulee dam sits in a wide, deep channel, or coulee, in the Eastern Washington basalt. David Alt's book is relevant because it explains (among lots of other things) where the coulee (and others like it) originated. The story begins with early settlers, who wondered at the scab lands in the area, and their contrast with the rich soils of the Palouse Hills. Some of these scab lands show stream beds much too wide to support current flows, and scouring as much as several hundred feet above the current channels. There are also potholes in the coulees, very numerous, and some of gigantic proportions. Further north, in Montana, there are the unmistakable horizontal lines of ancient lake shores, high on the hills and mountains of river valleys.

These and other clues led early geologists to wonder and speculate about ancient glacial lakes during the last ice age. T. C. Chamberlain was one of these, as was Joseph Pardee, who actually calculated the volume of water in what is now called Glacial Lake Missoula. The numbers are impressive. The lake held roughly 500 cubic miles of water, was nearly 2000 feet deep, and covered an area of roughly 2,900 square miles.

The problem was, it was all held back by an ice dam, an ice finger, actually, from one of the glaciers that moved down from Canada during the last ice age. And when the water in the lake became deep enough to float the ice dam, it gave way, resulting in a tremendous rush of water out of the lake that sloshed its way, making temporary lakes as it went, all the way to the Pacific ocean.

Along the way, this great flood formed many of the features we see in Montana, the Idaho panhandle, Easter Washington, the Columbia Gorge, and the lower Columbia. Alt has structured his book so that he takes the reader on a voyage from the lake's beginnings in Montana through the river valleys the flood scoured. Along the way he explains how the floods resulted in landmarks easily visible from interstate highways, including such features as Coeur d'Alane Lake in Idaho, the scablands and coulees of Eastern Washington, the Columbia River Gorge, and Lake Oswego in Oregon.

The book is nicely illustrated, with lots of black-and-white photographs of geological features as well as useful maps. The story, for the most part, is sequential, and follows the events of the flood from the moment the ice dam broke. An important point, though, is that there were many such floods. Perhaps three dozen or more. This cyclic behavior resulted from the creeping ice: as soon as the ice dam washed out, the glacial ice, continuing it's plodding movement, would begin damming the river again, and the process would repeat.

Alt's purpose in writing the book is to both tell the story of geological events, as well as to illustrate how scientists grapple "with an emerging scientific controversy." As he points out, "[S]ome handle it well, others miserably as personalities, pride, and outright prejudice supercede scientific evidence. While I found some of these stories interesting, for me they were a little distracting, particularly when Alt takes the apparent point of view that earlier scientists who did not readily accept the "monster-flood theory" were somehow bad scientists.

For example, Alt states on page 21:

"When J. Harlen Bretz first proposed his great flood, he could not say where the water had come from. He pointed to the enormous expanse of glaciated country to the north and vaguely suggested that the water had come from somewhere up there, somehow. Perhaps a brief interlude of much warmer weather melted an enormous amount of ice. Maybe a volcano erupted beneath the ice. It was a puzzle. People need not understand everything they know. It is perfectly proper in scientific discussions to recognize that a phenomenon exists without being able to explain it."

In hind site it's easy to criticize people for not "believing." But Alt does a disservice, I think, with his implications that such criticisms were somehow unfair. No doubt there were personal conflicts and bad manners, but overall, my perception is that the scientific community was pretty prompt about accepting the new theory once the evidence was presented. And, certainly, the cause of science is not advanced by accepting uncritically ideas for which only ad hoc explanations about "where all the water came from" are advanced. One need only review the circumstances surrounding the fiasco of "cold fusion" to understand the value in the scientific method of "believing" after the facts are established, and not before.

Philosophical issues aside, I really enjoyed this book. It's part of a class of books aimed at the intelligent arm-chair scientist (but of interest, I believe, to "real" scientists, as well) in which a particular geological micro-history is traced through thousands of years. For me, personally, this was a fun book. I enjoy geology, and I especially enjoy such books that take a particular historical event in geology and explain it in detail. It's the sort of book I can easily read while camping, or in the evening, at home. I highly recommend it.

In 1975, the original "Roadside Geology of Northern California," with the same authors, presented a new way for the amateur rock enthusiast to learn about the complicated geology of northern California. Unfortunately, it was painfully vague, missing important information found in other books of the series, such as significant insight into how formations developed and their ages (e.g., Cretaceous, Devonian, etc.). By in large, this Y2K update solves the problem, and expands the original's spatial coverage southward to San Luis Obispo and the San Joaquin Valley. The improvement in information is phenomenal -- partly because of the increased knowledge gained in 25 years as alluded in the preface, but mostly because of better writing and attention to detail. For example, the Chapter 4 (Coast Range) discussion on how different rock types develop from different areas of ocean sediments may be the best I have ever seen in any forum -- concise (4 pages) and non-technical, yet stuffed with information. Like several other areas of the book, it includes interesting insight into how geologists have handled the difficulties in classifying and sorting California's wild assemblage of rocks; for example: "During the late 1960s, geologists finally accepted that large parts of the Franciscan complex are almost hopelessly scrambled. They agreed to call these chaotic jumbles melanges....Recognition of melanges was, in a way, an admission of defeat." Other chapters contain similar nuggets of "inside" information into the processes of rocks and the way they are studied.

Of course, the foundation of this book, as in the whole series, is in its sequential descriptions and explanations of the rocks one encouters while driving various roadways. The improvement in detail here is vast as well. There are still a few ambiguities in rock age (e.g., Paleozoic/Mesozoic schists of the northern Klamath region...aren't the actual ages more precisely known?). A few typos or fragmented sentences appear to have escaped the proofreaders. But overall, this is a well-composed and thorough look at northern and central California geology for the layman. Residents and vacationers who want to know about the rocks they see must have this book. It has greatly helped me to understand the processes behind rocks I have gathered there.

The book provides a plethora of information for those who wish to see the many interesting and complex geological features of the northern and central areas of California. However, in order to make the best use of this book and fully appreciate the physical and historical geology presented, the reader should have a basic background in geology. This book will even refresh the memories of those folks with a somewhat oxidized recollection of rocks, minerals, geologic structures, and the like.

This book is not aimed at rock hounds, as its emphasis is not on collecting. The educated collector will find it interesting, though.

There are only two "problems" with this book. First, it will lengthen the trips you take as you look for the geologic features it discusses. Second, you may endanger your life as you stop to look at the road cuts discussed in the book or divert your gaze from the road to rocks while driving.