By Jack Caldwell

I own eleven of the Roadside Geology books. One of my ambitions is to own all thirty or more. It is not the possession of more books that interests and excites me. It is using the books, and that implies traveling long distances through vast vistas, exploring the geology along the way.

The premise of each book is simple: you are driving along a highway, a state route, or just some interesting byway—the text describes the geology of what you see along the way. There is an introductory section, written in plain prose by an expert describing the overall geology of the state through which you are driving. The ads are true: each book is “loaded with maps, photos, cross-sections and expert descriptions.”

Not enough information for an exploration geologist, or a mining engineer, but probably as much as a reasonable geotechnical engineering ambling around the countryside needs. For example, here is my take on the geomorphology of some of the states I passed through on a recent trip from Iowa to British Columbia partly fortified by books on Nebraska, Wyoming, Idaho, Utah, Oregon, and Washington.

  • Iowa: This is a young landscape. A mere 14,000 years ago the last glacier receded leaving behind a rolling landscape of random rises and depressions and a crazy network of stream leading to the rivers that cut the state and flowing to the southwest. On either side of the state are the great rivers that formed on the edges of the glaciers: the Missouri on the east and the Mississippi on the east. The glaciers left behind those deep clayey soils that make farming so productive.
  • Nebraska: This is a very old landscape. For hundreds of thousands of years the streams and rivers have flattened the state so that now one travels 450 miles from the Missouri to the western border along the Platte River that slowly meanders along a flat broad flood plain. During the periods of glaciation while Iowa was under ice, the wind blew silt from the eroding Rockies across Nebraska depositing those soils that now need irrigation to produce a crop.
  • Wyoming: Now up through the mountain building that has pushed up the Rockies and this state for the last 65 million years. The landscape is rugged: buttes and mesas, mountains and deep valleys that expose the old sediments laid down in the age of the dinosaurs when this part of the world was probably near the equator, the temperature was hot, and vast floods moved huge quantities of clay and silt and sand into shallow mudflats and lakes and swamps. These sediments are uplifted to 8,700 feet, the highest point along I80 and the Continental Divide at 7,000 feet.
  • Utah: I have traversed only the eastern edge, coming down through the Wasatch Mountains that are the western edge of the Rockies and that fall thousands of feet to the Bonneville Flats, once an extensive inland sea, and now a shrunken salt lake.
  • Idaho: I traversed only the flat part of southern Idaho. I avoided the mountains to the north. The flat lands where I traveled are the vast outpourings of lava that came up as the continent moved west over the spot that now is Yellowstone and the volcano pipe that underlies the park.
  • Oregon: I got to know the mountains of northeast Oregon better than the Roadside Geology of Oregon describes. For the first 70 miles across the pass through the vast mountains, the road was awash in new snow and slush. The great black basalt cliffs rose up from the road and into the mist and falling snow. Then into a great valley and I sped up for the next 100 miles, until an overhead message board announced that chains were required for Dead Man’s Pass up ahead. On the next day under a bright clear sky towards Deadman’s Pass. Past a hundred trucks putting on chains. Words cannot capture the infinite variety of snow and ice and water and sand and gravel and asphalt—even combinatorial mathematics would struggle. Sometimes on pure snow; sometimes on ice covered by sand and gravel; sometimes on sun-exposed asphalt. The crest is 4,193 feet and you think “that’s it.” But that is not it—for Dead Man’s Pass still lies ahead at lower elevation but still snow covered. Finally a crawl over the pass, the sun out all the way, and the mountains and cliffs a sparkling white wonderland. Then six miles of six percent downgradient. More slow driving and down and yet down more until the valley and clear roads and speed greater than 30 miles an hour.
  • Columbia River Gorge: The first 50 miles are desert—dry scrub dotting the basalt. Then there were 50 miles of snow-covered hills and cliffs, although the road was clear. The final 50 miles is in the green trees and heavy vegetation of the coast road. Like driving down the Grand Canyon.