In the second book of Annals of the Former World, John McPhee returns east to examine the geology of the Appalachians along I-80. Beginning with the Delaware Water Gap, he travels along the highway with geologist Anita Harris exploring the road cuts to see what can be determined about how the landscape developed. The two continue on this route through Pennsylvania and into Ohio, where they explore Kelley’s Island, travel along the Cuyahoga River for a spell, and end at the Indiana Dunes.
Having explained the basics of plate tectonics in Basin and Range, McPhee now travels with a geologist who is skeptical of the broad application the theory has found, particularly in relation to the Appalachians. Harris takes issue with the idea that the mountains were formed by the ramming of the African coast up against North America. She believes that a study of the rocks does not support this concept.
In Suspect Terrain is deeply concerned with glaciation. As well as explaining how glaciers could have formed this area of folded and complex geology, McPhee breaks off to expatiate on how the theory of the Ice Age came about, among other geological ideas. He also tells how Harris herself figured out how to use the color of conodonts, a kind of fossil, to make it easier to find the conditions for oil.
I find it fascinating to try to imagine the pictures of the earth that McPhee describes, how different they are from the continent as it is today. McPhee tells us how rivers ran to the west instead of to the east, huge tropical seas took up the middle of the continent, the glaciers shoved rock down from Canada to create places like Staten Island.
McPhee is an extremely interesting writer. To be sure, the subject matter, the ideas it evokes, and the language he uses demand full attention, but this series of books is involving.