A Few Geologic Words and Concepts Through Time (via Google Books Ngram Viewer)

I'm not sure how I got started on checking different words and concepts on Google Books Ngram Viewer yesterday, although my "History" tab suggests to me that it might have been related to some reading I was doing on science fiction. As for geology and geologic concepts, we'll first take a quick look our main concept, geology:

We see an upsurge in the word "geology" in the early 1800s, coinciding with the rise of active geology in Britain and elsewhere, with fairly steady overall use of the word since then. And this is what Google does when I click the "case insensitive" box:

The recent drop off in "geology," which began in 1980 or 1981, no doubt resulted in part from the changes at many colleges and universities in department names from departments or schools of Geology to departments or schools of Geosciences, Earth Sciences, Earth and Planetary Sciences, Earth and Environmental Sciences, and others. Andrew Alden has a bit more to say about "geology" v. "Earth science" v. "geoscience" here.

But it looks like that doesn't explain the decrease in "geology" entirely:

Any speculations?

And, for what it's worth, "geologist" began to decline in 1970:

As did "geologists":

As for other geologic concepts and words, I'll just show a couple more right now, and maybe get into some others later. (The Ngram Viewer is fascinating, and it's easy to just keep going on seemingly forever.)

This next set explains itself:

"Subduction" v. "plate tectonics" v. "continental drift" v. "geosyncline."

There's an interesting little blip in "subduction" from 1953 to 1959; not sure if this relates to anything real in the history of plate tectonics or is related to something else. Surely "subduction" prior to 1900 is unrelated.