Drive-by geology

The Peshastin Pinnacles

The Peshastin Pinnacles

It’s hard to go exploring in the West and not get a little interested in geology. In a few days’ drive you get crags of rock sticking up from a normal-looking dirt hill, cliffs of hexagonal rock columns, flat desert as far as you can see, high valleys ringed by even higher peaks, cinder cones jutting up from huge beds of lava, and giant, jagged mountains that dispensed with foothills, so you can practically walk up and put your hand on them. And we haven’t even gotten to Yellowstone yet. What’s going on here?

What we need is someone to explain how all this happened in layman’s terms, because, as in all specialized fields, geologists speak their own language. You can dig around online for an explanation but you have to stop and look up definitions for every third word. And the story is complicated; you have to get your head around a 3-dimensional history of how the earth formed over space and time—a very long time.

So you get little bits and pieces of disconnected information, from park interpretive signage, park rangers and from the Internet. The Peshastin Pinnacles in central Washington—sandstone crags standing up from the rolling hills around the Wenatchee River—were the result of a geologic event some 50-30 million years ago on the other side of the Pacific, which shoved Washington’s coastline up vertically.

Columbia River Gorge

Columbia River Gorge

You wonder at the basalt columns that line the Columbia River and scattered across eastern Washington, Oregon and Idaho, the result of molten rock spewing through cracks in the earth’s crust eons ago, then cooling into 6-sided columns.

And the volcanic wonderland of the Craters of the Moon, in eastern Idaho! Who isn’t fascinated by volcanoes? The Yellowstone Hotspot, a column of fluid rock, bubbled up from 600 feet below the Earth’s mantle 10-6 million years ago, like a big old lava lamp. Eruptions along the Snake River Plain created massive craters tens of miles wide; pre-existing mountain ranges were partially blown away, or swallowed when magma chambers collapsed.

Buffalo Cave at Craters of the Moon National Monument

Buffalo Cave at Craters of the Moon National Monument

Then, in the last 15,000 years, and as recently as 2,000 years ago (they say eruptions happen here about every 2,000 years), eruptions created The Great Rift, covering about 700 square miles and one of the deepest open volcanic fissures in the world today—much of it protected by this National Monument and Preserve. You can crunch around on the cinder cones, bang your head crawling into caves created by lava tubes, and wonder if the next eruption is coming any time soon.

If that wasn’t enough to spark an interest in geology, the Grand Tetons certainly will. They say that the rock in these mountains is 2.7 billion years old, but the mountain range itself only began to form about 10 million years ago, when earthquakes along the Teton fault jutted up the peaks while dropping the valley floor. It’s impossible not to be awed.

The violent collision of tectonic plates, Missoula floods, massive glaciers. It makes you curious about how it’s all connected. I asked Ranger Holly at Craters of the Moon for a book recommendation on layman’s geology. Unfortunately there isn’t one book, besides a geology 101 textbook. But there’s a series of “Roadside Geology” books for each state, which sounds right up my alley. Now I just need to stay in one state long enough to get it and read it.

3 thoughts on “Drive-by geology

  1. Sue and Bruce–What a marvelous adventure you two are on! I’m enjoying the travelogue details and your comments bring all of your followers into the front seat of your vehicle. I’m looking forward to more of your posts.

    Have fun and enjoy the trip–“Live life to the fullest, each and every day. This is NOT a dress rehearsal”!


  2. Carters of the Moon is such an amazing area out in the middle of Nowhere Idaho.
    One August I drove with our Nate to Montana State U in Bozemen dropping him off then headed down to Yellowstone for a night and connected with a group for some day hiking then drove to Craters and connected with a group and explored the caves & hiked to the top of the crater. Then on to Boise area, where my sister lives. Was a fun time, but a lot of very long long roadways in that stretch. I think I was listening to a book on tape.
    Enjoy your journey!

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