Bulletin E-Edition:
Online maps detail what's underfoot
By Kate Ramsayer / The Bulletin
Published: May 17. 2007 4:00AM PST
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The brightly colored map isn't your ordinary guide to roads, trails or topography - most of those don't include terms like rhyolite, andesite or volcaniclastic in the map key.
But this particular map details the different rock formations and features of Central and Eastern Oregon, pulling together information from previous geologic surveys as well as new studies. Eventually, it will detail the entire state. Its creators hope that the new interactive, online map will serve as a handy tool for scientists, city planners, teachers and the geologically curious who are looking for more information about the ground beneath their feet.
"It takes into account so many more things than just the topographic features of the landscape," said James Roddey, Earth sciences information officer with the Oregon Department of Geology and Mineral Industries.
"We've gone into so much greater detail in the areas that we have online right now than ever before."
The map, put together by the geology department and now available on its Web site, www.oregongeology.com, is half done, he said. During the next three years, the department will work to complete the western portions of the state, and will also update the existing map as more information becomes available.
But for now, people wondering how many million years ago the basalt they hike on was formed, or whether there's a geological fault running underneath their house, can check the map.
"It's a really, really great place to start, in terms of understanding what's under your feet or what you're going to go look at," said Ellen Morris Bishop, director of the Oregon Paleo Lands Institute. It does, however, help to have a Geology 101 textbook close at hand to understand some of the definitions and terms, she said.
But looking at the map that outlines the stratigraphy of the area can tell people how old the rocks are, and when they were formed as compared to the rocks around them, she said.
To the southwest of Bend, for example, is a rock formation labeled "Quaternary Volcanics," which the key defines as basalt and basaltic andesite - gray or black volcanic rock - lava flows that were formed within the last 1.8 million years. East of U.S. Highway 97 between Bend and Madras, however, the map identifies the "Dalles Group," which is made up of sedimentary rocks that are between 11.2 million and 1.8 million years old.
By clicking on a box on the tool bar and zooming in, people can also identify the fault lines that crisscross the state, including through Bend and surrounding Burns.
"That really gives you a good idea of how very earthquake-prone we are," Bishop said of the state.
Everyday use
The map could also be a tool for teachers focusing on Earth science, as well as hikers who want to seek out specific types of rocks on treks, she said. She added that the Paleo Lands Institute is working with the geology department to translate more of the map's information to layman-friendly language.
But the map can also be used by people with professional inquiries relating to the ground, Roddey said. City planners could use it to determine if they need to be concerned about ground stability before giving buildings the OK, or can even use the elevation data on the maps to route sewer lines through a town.
The geology department is using a new technology involving lasers that survey the ground from airplanes, resulting in highly detailed information about the ground's surface, stripped of buildings and trees.
"You're seeing the bare Earth, and with it you can see where ancient landslides occurred, earthquake faults - things people haven't seen before," Roddey said.
With training, people can interpret this to see, for example, where landslides happened in the past and where they could happen in the future, he said. The geology department is helping Oregon City develop new landslide ordinances and susceptibility maps based on this information, which identifies 10 times more landslide potential than previous studies.
Around Prineville, geologists with the state are continuing to survey the rocks in the area, looking for places where people could drill wells for water for an expanding population, said Mark Ferns, regional geologist with the department's Baker City field office.
'Different applications'
Geological surveys can also provide useful information about slope stability, energy and mineral resources, and potential hazards such as if minerals might be seeping into water, he said. They can tell people what kind of soils will be in an area, and therefore what kind of crops or trees would grow best in an area.
"There's a ton of different applications," Ferns said.
On a detailed level, maps identifying where the different kinds of basalts are located can pinpoint whether an area will have lots of water availability, whether the rocks would be good for road material or decorative stone, or whether an area might be susceptible to landslides.
Ferns and other geologists have been doing field work to identify the distribution of different rock units, generating patterns to get more up-to-date maps.
They look at different outcrops, plotting where the rocks are and taking samples to figure out the age and other characteristics of the formation. By collecting data, they have even drawn connections between geological features across the High Desert.
"Everyone's eyes are drawn to the Cascades like a magnet, and sometimes when you do that, you miss what's right at your feet," he said.
Kate Ramsayer can be reached at 617-7811 or at kramsayer@bendbulletin.com.
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