Reading the Rocks by Marcia Bjornerud

Source of book: Borrowed from the library

This is an unusual book for the reason that I recommended it to someone else before I read it myself, which is not how I usually do things. However, that friend said she liked it, so I figured I would have to go read it.

Bjornerud is a professor of geology at Lawrence University, so she knows her stuff, but also has a rather poetic writing style. I was expecting a more systematic study of the subject, but won’t complain about the way she approached the topic, other than to say that the book makes more sense if you have at least had a grade school course on earth science.

A little background on this may be helpful. I was homeschooled from second grade onward, in an era when homeschooling went from fringe to mainstream. When I started, curriculum wasn’t easy to obtain - if I recall, even the mainstays of religious homeschooling curriculum now had to be purchased on the gray market. Now, of course, pretty much anything used in public or private schools can be readily found in homeschool-specific versions. And between the internet and the wonders of capitalism, there is so much out there, much of it free. (For example, Phil Plait’s wonderful Crash Course Astronomy videos.) But it was not always so. About all we had was A Beka and PBS.

So anyway, because of what was available and my family’s religious beliefs, the curriculum had a lot of gaps. While my dad wasn’t a young earther, that was (and is) the dominant belief in Evangelical circles, and A Beka definitely fell into that category. And not just by claiming evolution was an atheist conspiracy, but by ignoring or glossing over much of geology, because that led to some uncomfortable places for their theology.

I didn’t particularly suffer from this deficit, though, because I was (and am) a voracious reader, which my parents encouraged. I probably knew more about science in general than most kids my age, and our regular trips to geologically interesting places gave me field experience as well. To be clear, I got a solid academic education. However, I do know that many homeschooled kids do not get this kind of background, and at least in my experience, science and math tend to be weak points for many. (To be fair, science and math are weak subjects for Americans in general, compared to the rest of the first world.)

Despite the YEC propaganda in the culture I grew up in, I don’t think I ever bought into the idea of a young earth. The problem was, there was just too much overwhelming evidence all around. I live in California, which, like most of the western US, has a lot of exposed rocks. And it has earthquakes. And huge mountains. In fact, in geological terms, our mountains are fairly young, which means the way they were formed is rather apparent to the eye, if you know what to look for.

I have lived within about 50 miles of the San Andreas Fault for most of my life. And that fault has created features in the landscape which tell stories. There is Vasquez Rocks, famous for its use in film, which was a favorite destination when I was a kid. There, the layers of breccia and conglomerate are tilted and cracked from the pressures of the fault, and contain fossils from the past.

At various places along the fault, like at the Carrizo Plain National Monument, you can see where hills and creek beds and rock formations have become displaced by the movement of the fault.

Wallace Creek at Carrizo Plain NM in 2014. 

The kids are literally standing on the fault, which displaced the stream bed about 600 feet. 

Crazy dry that drought year - this year, everything was covered in flowers - so many you could literally see it from space.

Even driving interstate 5 north from Los Angeles, you can see where the hills on each side are quite different.

However, the two most interesting features have to be Pinnacles National Park and Point Reyes. In each case, entire rock formations are displaced by hundreds of miles. In the case of Pinnacles, the rest of the extinct volcano is located far south. In the case of Point Reyes, the whole peninsula was moved up the state over time, and it clearly was just stuck on the side there.

And then there are the other western places of geological interest: Zion, Bryce, the Grand Canyon, Lassen, and so many more. All these rocks tell stories of their origin, and those stories do not fit with a young earth. This much was obvious even to teenaged me.

Back to Reading the Rocks. The strong point of this book is in the explanations of how we read them. Contrary to the Evangelical conspiracy theories of my youth, geology isn’t just a made-up explanation to exclude the divine. Rather, there are known processes by which things happen. Plate tectonics are responsible for more than you would realize, radiometric dating does indeed indicate the dates on many rocks, and the fossil record does indeed tell of a history of life very different from our own age. As Hutton put it, “The ruins of an older world are visible in the present structure of our planet.”

Probably the chapter that had the most material that I didn’t already know was the one focusing on the role of water in geological processes, particularly subduction. Pretty fascinating stuff.

Also of particular interest was the chilling account of mass extinctions of the past (including a period when the earth got chilled.) It is frightening to me how cavalier many people are about climate, thinking that there is no risk. The underlying dynamics have been understood for hundreds of years, and we can see from the past that bad things can accelerate. But I guess that goes along with a general hostility toward science in this country, and a tendency to make everything into a partisan issue. (Yeah, I actually remember when Republicans were in favor of conservation and someone like Nixon could found the EPA without half the country thinking it was a Commie conspiracy…)

I also appreciated the way that the author worked in the history of how geological ideas and techniques were developed. It really helps to know how people reached conclusions, not just what they discovered.

Anyway, there is a lot to like in this book. Bjornerud writes well, and keeps the topic interesting and memorable. I will definitely continue to recommend this book.

Just one final thought to end it. Early in the book, the author notes that geology can be intimidating, because of the language, much of which originated before geologists had our modern understanding. Thus, the terms are often anachronistic and misleading.

But nomenclatures outlive the systems that spawned them, and over time the technical vocabulary of geology has become an idiosyncratic melange of anachronisms, synonyms, and some genuinely useful terms.

And, in a move that warms my heart, she then quotes from Mark Twain’s autobiography about the riverboat mate whose reading consisted solely of Lyell’s Geology.

All he wanted out of those great words was the energy they stirred up in his roustabouts. In times of emergency he would let fly a volcanic irruption of the old regular orthodox profanity mixed up with and seasoned all through with imposing geological terms, then formally charge his roustabouts with being Old Silurian Invertebrates out of the Incandescent Anisodactylous Post-Pliocene Period and damn the whole gang in a body to perdition.