Nature up close: The Painted Hills

Oregon's Painted Hills.

By "Sunday Morning" contributing videographer Judy Lehmberg.

As a biologist, I tend to look at the world through a biologist's lens. One of my favorite pastimes is 65 m.p.h. plant and bird identification, a hobby that has led to a number of arguments while driving, followed by U-turns to see who was right. It definitely makes cross-country drives entertaining, but also makes it hard to pay attention to all the other roadside wonders, especially geological features.

That's led us to remark, "There is a lot of geology out there," without learning much about it.

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An elevated boardwalk along the Painted Cove Trail, in the Painted Hills section of the John Day Fossil Beds National Monument, near Mitchell, Oregon.

After traveling through a large part of the southwest with a geologist a number of years ago, I realized how much I had been missing by ignoring the geology.  As our friend pointed out, if there weren't any rocks, there wouldn't be any soil – and without any soil, life, as we know it, would not exist.

The type of soil in an area is determined by the type of rock, since soil is a combination of 45% to 49% eroded rock; 2% to 50% water; 1% to 5% organic material; 2% to 50% gases; and less than 1% bacteria and other microorganisms.

That got my attention. Now, I do pay attention to the geology of areas new to me, and find it both fun to learn and beautiful, such as the Painted Hills.

The Painted Hills in eastern Oregon are not only striking, they are a lesson in stratigraphy – the study of rock layers and how those layers were deposited.

Once you know a little stratigraphy, a drive through much of the western U.S. is literally a drive through geological time. To understand where the Painted Hills get their color, it is first necessary to know they were formed from layer after layer of volcanic lava and mud flows, overlaid by volcanic ash deposits, over the last 55 million years.

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The tannish-cream colored deposits are rhyolitic ash that is about 70% silica.

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The dark red layers are mostly iron oxide.

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The black spots are manganese nodules that may have formed when plants fixed manganese, or, more likely, when manganese-rich salts concentrated as pools of water rich in the mineral dried up. 

      
Judy Lehmberg is a former college biology teacher who now shoots nature videos.

      
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