Spring/Summer 2006: Land

Every Hill Has a Story

A geologist explains why Oregon's landscape looks the way it does

Interview by Gail Wells

Ellen Morris Bishop is the executive director of the Oregon PaleoLands Institute in Fossil and a geologist, photographer, and environmental advocate. She has taught and conducted research at Lewis & Clark College and at Marylhurst, Eastern Oregon, and Oregon State Universities, and she reaches diverse audiences through her scholarly and popular writing. She is the author of Hiking Oregon's Geology and In Search of Ancient Oregon. She lives in eastern Oregon.

GW: What prehistoric influences have shaped Oregon's landscapes?

EB: Most people's perception of landscape is lacking the same sense of time that geologists carry around with them. There's a huge, vast complexity of processes and time that contributes to this landscape that we see today. That's one thing that is very evident in the landscape if you take time to look at it--that is, the sense of really, really deep time.

Many people tend to think of the Ice Age as some- thing that happened long ago. In fact, the Ice Age is fairly recent. Similarly, the geologic features that are Oregon's icons are comparatively recent. However, their development relies on older past history. For example, one of Oregon's geologic icons is the Columbia River Gorge. The Gorge was not exclusively sculpted, but was certainly influenced a great deal, by floods passing through ten or fifteen thousand years ago. Those floods came from a much older landscape. They came across, accreted, and added terrain. These recent events would never have happened were it not for the events that happened in antiquity, the ones that built this whole landscape and allowed the Columbia River Gorge to be carved.

There was an ancestral Columbia River, fifteen or seventeen million years ago, that followed a channel that was south of the present channel. At one point this paleo-channel ran where Mount Hood rises, or rather a bit to the south, although of course Mount Hood is a much, much younger feature. Repeated Columbia River basalt lava flows then forced the river to the north until it reached where it is now, probably about twelve million years ago.

Then much, much later, at the close of the last Ice Age, or about fifteen to twelve thousand years ago, a glacier repeatedly blocked the drainage from the Clark Fork River, creating a huge lake. When the ice dam broke, enormous floods surged across central and southeast Washington and down the Columbia River. These floods eroded the silt and soil from central Washington and deposited them in the Willamette Valley. We are hugely indebted to those floods. They're the reason we have Willamette Valley grass seed and Willamette Valley wine--we owe these things to Washington's topsoil. Hopefully they won't ask for it back any time soon!

These floods are an example of a process that's relatively recent that has changed the playbooks. The Cascades that we see--look out the window in Salem and you see Mount Jefferson, or look out the window in Portland and there's Mount Hood--are less than a million years old, which, again, is relatively recent. Over here in Fossil, I live among volcanoes that weren't as big as Mount Hood, but they're forty-five million or fifty million years old.

Certainly, the Cascades influenced the settlement of Oregon, because the Cascade rain shadow created this vast, fertile Willamette Valley. Settlers came racing through Eastern Oregon and wrote in their diaries [about the beauty of the landscape]. But they wanted to get out of there and get down to the Willamette Valley, where they could grow food, and there were other people and you could do commerce.

GW: What would you say are the main human influences on Oregon's landscapes?

EB: Humans are becoming change agents more and more right now. For example, humans are now in charge of the atmosphere. It used to be that volcanoes were in charge of the atmosphere. There's a new research paper out that proposes that tectonic rates of movement along faults are influenced by the amount of rainfall. The study uses computer models to show that higher levels of rainfall will speed plate movement. As we change the climate in the Pacific Northwest, we change precipitation patterns, because we're changing the CO2 and H2O and the other components of the atmosphere. And therefore we are probably, in very, very subtle ways, modifying plate tectonic processes, including possibly the mechanisms and severity of subduction-zone earthquakes, and rates of uplift in the Cascades and in the Columbia Gorge.

These changes are very, very subtle, not even noticeable unless you're a supercomputer, and we should keep in mind that this study is based on a computer model. These changes are on scales we can't see as we're driving down the Gorge. You're not going to say, "Oh, look out. There's uplifts ahead!" But you are going to say, "Oh, look out, there's a landslide ahead!" which is certainly a geologic process. But we now have instrumentation that can monitor slight changes in raised uplifts, slight changes in erosion. So we know that humanity is altering the rates of geomorphic processes on the planet.

GW: I've never thought about climate change so directly affecting geologic processes, although that intuitively makes sense.

EB: Well, it affects geologic processes because things are connected. As a culture, we tend not to recognize that. We tend not to recognize that the amount of CO2 in the atmosphere influences the rate of growth of plants, for example. The rate of growth of plants influences the amount of carbonic acid that gets produced. The amount of carbonic acid influences the rate of weathering of most rocks. And so, on and on we go. We don't make those connections very well at all.

I think some indigenous cultures did make those connections, however, because they lived at a slower pace. They may not have understood the rate of growth of plants or the changes and balances of CO2 and how that affects climate and storm intensity and all those other things. But the Nez Perce did, for example, recognize that certain stones in the Snake River Canyon didn't really belong there. These stones were erratics, like the erratics we have here in the Willamette Valley. Indigenous peoples would look at these and say, "Wow, it must have taken one heck of a force to move this. Maybe it was a flood, maybe it was something else, but this is a rock of great power."

In fact, these were rocks that were hauled into Hells Canyon about 12,000 years ago by the ancestral Great Salt Lake, greatly swollen by glacial meltwater from the Wasatch Mountains and other ranges. The lake spilled over Red Rock Pass and washed down the Snake River and deep into Hells Canyon, carrying these erratics with it. But my point is that the Nez Perce and Bannock peoples noticed those exotic rocks that didn't belong there, and they used them. These are the only places that you find petroglyphs that are related to power. I'm not sure that most of us look at our landscape in that much detail.

GW: What would you say are the main cultural meanings people attach to Oregon?

EB: Humans are creatures of the familiar. You have your standard image of Oregon, that it's green and it has Mount Hood, and Mount Hood is in the east, not in the west. So it's part of the perception. In a way we can blame geology for that, because the west side is green and verdant by virtue of two mountain ranges.

One of these ranges, the Cascades, has been more or less in the same place for the last thirty-five to forty million years. You can think of the Cascades like a family with multiple generations. The oldest Cascade volcanoes are about thirty-five to thirty-eight million years old. Like long-dead ancestors, these are now forgotten, or at least not visible any more. Many different peaks have "died" or "passed away" in each generation. The youngest ones, like Hood, are less than a million years old--even though Hood is a mature volcano that geologists consider active. Seven hundred thousand years is still a long time, even if you're a volcano!

The other range, the Coast Range, is a fairly recent addition, at somewhere around thirty million years. It is the western edge of the Willamette Valley. Together they've created this geographic and geological entity known as the Willamette Valley, which is this great place that captures rain from Pacific storms, and it's temperate and moderate.

When you get over on the other side of the Cascades, we have an older generation of volcanoes, but they're long gone. Nobody thinks the landscape of the Painted Hills looks much like [many peoples'] vision of Oregon, but the Cascades contributed to the eastern Oregon landscape, because the Painted Hills are composed of ash from the creation of the Cascades. So if you're feeling uncomfortable about being over in a dry, arid place, you could go to the Painted Hills and put your hand on the soil and know that it had come out of a very old Cascade volcano, and perhaps it would make you feel better.

Also on the east side of the Cascades, Oregonians have much more of a ... I don't want to say a closer attachment to the land, but more of a feeling that natural resources are important and are the major way of making a living. Communities do not want to let go of their attachment to natural resources as their principal economic livelihood. It really makes sustainability a challenge. We haven't yet gotten to the point of thinking of ecosystem services as something that we can make a living from, and we don't know quite how to do that. But we do know that we used to be able to harvest trees and we used to be able to make more of a living directly from the land. I think the more urban mindset of the Willamette Valley is much more about services and commerce and other things. So, there's certainly a stronger attachment to landscape here on the east side, and the cultural meaning that Oregonians here attach to Oregon is that it's a place that produces natural resources.

GW: Are there realities about the landscape that people aren't aware of?

EB: Yes, and one is that everything is connected. If you grow a tree in one place, you're using resources here that will be recycled elsewhere. If you exhale, the CO2 you breathe out benefits a tree. This interconnectedness may be considered a new-age idea, but it's also a scientific principle--where does everything go?

From geology we can see that, over both short and long time frames, nothing stays the same. There's weather and there's climate and both are prone to change. Climates have changed drastically through geologic time. We need to take some lessons from the Permian, for example, when 95 percent of the animal life on the planet died because there was too much CO2 and methane in the atmosphere. Temperatures were out of control, and the atmosphere was mostly toxic. If you weren't at sea level, you didn't survive.

Geology holds many connections and lessons that we don't often think about. Geology is kind of like genealogy, except it goes back a very long way. We rarely think about deep time--this long, complex history of the earth. A lot of people look at hills or mountains and never quite get the idea that they are composed of geology, and that every hill has a story--a lot of stories. Geologists need to become better storytellers, because we are all walking around on, supported by, and products of, an astounding history.

Published in the Spring/Summer 2006 issue of Oregon Humanities.

© 2006 Oregon Council for the Humanities