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Archive for the tag “Oregon geologic history”

“Oregon Rocks!” My new book about Oregon’s Wonderful Geology

I’m very happy to announce that my new book, Oregon Rocks! A guide to 60 Amazing Geologic Sites, is out there and available. Although the title always makes me cringe a little, I’m excited and proud of this project, which took me three years to complete and took me all over my beautiful state. At the risk of being overly exuberant, here are some excerpts!

If you click on the image below, you can actually read the table of contents (left) and study the site map. Both these illustrations group the sites in one of Oregon’s six physiographic provinces: The Coast Range, Klamath Mountains, Cascade Range, Lava Plateaus, Blue Mountains, and Basin and Range.

Table of contents and site map of Oregon Rocks!

The site numbers are especially important –not only because they key to the map location and page numbers in the book –they also refer to the timeline and schematic cross-section across the state. I’m especially proud of this part because it lets you place each site into the context of how the entire region evolved. Click on the timeline and maps below to see what I mean!

Geologic timeline, cross-section, and geologic map (pages vi and 4) of the book. Note how the site numbers appear in all three diagrams.

As an example –say you hike up Spencer Butte, just south of Eugene. It’s a great hike, by the way –and graciously posed for the cover photo. You can see from the geologic map (lower right) that it’s part of the western Cascades –and you can find the same site on the timeline in the same color –and on the cross-section. From the cross-section, you can see more context: the western Cascades are cut by intrusive bodies (which include Spencer Butte) and predate the High Cascades and are part of the cover sequence overlying the accreted terranes.

Please check out my earlier post about this cross-section and Oregon’s geologic history if you’re interested!

And here’s some of the interior! Most sites consist of two facing pages, but some are just a single page, and others are 3, even 4 pages long. The book measures 9″ by 8.3″ and totals 154 pages in length (160 if you count the front matter) all in color. It has more than 180 of my photos and more than 70 maps and diagrams. Chelsea Feeney employed her map wizardry to make the maps and diagrams look really beautiful.

Part of the book’s interior. On the left is page 2 of Cape Blanco. Click to see larger.

Many of the photos are available on my geology photo website for free download –and I’m working to add more if you want or need any for your own purposes –and by all means, if you’re teaching a class or something like that and are looking for specific images, please contact me!

Many of the photos are available on my geology photo website for free download –and I’m working to add more if you want or need any for your own purposes. And by all means, if you’re teaching a class or something like that and are looking for specific images, please contact me!

And if you’re interested in purchasing the book, you can get it from Amazon or direct from Mountain Press –and Mountain Press has tons of other great geology books too!

Thanks for reading!

Just scratching the surface. A geologic cross-section of Oregon speaks to unimaginable events.

The cross-section below runs from the Cascadia subduction zone across Oregon and into eastern Idaho.  It outlines Oregon’s geologic history, beginning with accretion of terranes, intrusion of granitic “stitching plutons”, and deposition of first North American-derived sedimentary rocks, and ending with High Cascades Volcanic activity and glaciation.

Schematic geologic cross-section across Oregon, from the Cascadia Subduction zone into western Idaho.

Schematic geologic cross-section across Oregon, from the Cascadia Subduction zone into western Idaho.

The cross-section barely scratches the surface of things. Moreover, it boils everything down to a list, which is kind of sterile. But the cross-section also provides a platform for your imagination because each one of these events really happened and reflects an entirely different set of landscapes than what we see today.

Think of the CRBG about 15 million years ago. The basalt flows completely covered the landscape of northern Oregon and southern Washington. Or the Clarno volcanoes –only a part of the green layer called “Clarno/John Day”. They were stratovolcanoes in central Oregon –when the climate was tropical! Or try to wrap your mind around the accreted terranes, some of which, like the Wallowa Terrane, contain fossils from the western Pacific.

To emphasize this point, here’s Crater Lake. Crater Lake formed because Mt. Mazama, one of the Cascades’ stratovolcanoes, erupted about 7700 years ago in an eruption so large and violent that it collapsed in on itself to form a caldera. It’s now a national park, with a whole landscape of its own. And if you visit Crater Lake, you’ll see evidence that Mt. Mazama had its own history –which dates back more than 400,000 years. But Crater Lake and Mt. Mazama make up just a tiny part of the Cascades, which are represented on this diagram by just this tiny area that’s shaped like a mountain.

Crater Lake occupies the caldera of Mt. Mazama, which erupted catastrophically some 7700 years ago.

Crater Lake occupies the caldera of Mt. Mazama, which erupted catastrophically some 7700 years ago.

So the cross-section is kind of sterile and just scratches the surface. But what makes geology so incredible is that we’re always learning new things and digging deeper –and we know we’re just scratching the surface –that there will always —always— be something  to learn.


click here and type “Oregon” into the search for photos of Oregon Geology.
click here for information about the new Roadside Geology of Oregon book.

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