Hiking in the thin air above 8,000 feet in the eastern Wallowa Mountains last week, ascending a slope of musical shards of shale, an odd pattern caught my eye. I bent to pick up the small, flat piece of gray rock and examined it closely. It was imprinted with the unmistakable rayed patterns of small sea shells. Knowing what to look for, within minutes I found more such fossils. How these rockbound imprints of ancient marine life came to clink and rattle down a mountainside over a mile-and-a-half above today’s sea level is a marvel that causes even the most learned geologists to scratch their hoary heads.
The approximately 360,000 acre Eagle Cap Wilderness that encompasses the heart of Oregon’s Wallowa Mountain Range is a favorite of horsemen, hikers, fishermen and hunters. Photographers, naturalists and especially geologists are also drawn to the range’s remarkable variety.
Unlike the younger and more homogeneous Cascades, the complex Wallowas come in all ages, shades and compositions. Of the range’s approximately two-dozen summits over 9,000 feet, few share the same appearance or geological makeup. Eagle Cap itself (9,595 feet) and several of its high neighbors are composed of white granite reminiscent of the High Sierra. Yet, just five miles to the north, the range’s tallest peaks, Matterhorn and Sacagawea, are limestone and marble. The adjacent Hurwal Divide is built of a reddish volcanic material. Aneroid Mountain (9,702 feet) to the east is topped with brown volcanic basalt.
I’m no geologist, but even the untrained eye can see that the Wallowa Mountains are a contorted hodgepodge of igneous and sedimentary rocks ― dazzling granite upthrusts rent by dykes of frozen black lava; shales, sandstones and limestones of various hues; metamorphosed andesite lavas of green, gray and purple; ancient sea beds, over-run by thick layers of lava, thrust upwards and split apart by tectonic shifts and upheavals, then deeply carved, compressed and ground down by massive ice floes.
Sit upon a Wallowa summit, as we did, and take-in the rocky color shifts, streaks, veins, swirls, and anomalies in these mountains. Look how ridges change abruptly from gray to brown, red to white, rounded to jagged. It is as if some playful god kneaded and juxtaposed the elastic rock like lumps of dough and chuckled at his haphazard handiwork.
One theory suggests that the weird Wallowas are, in fact, a wayward southerly fragment of the Insular Belt, a chain of similarly constituted landforms that includes Vancouver Island, the Queen Charlotte Islands and even the Wrangell-Saint Elias Mountains on the border of Alaska and the Yukon! I wonder if I were hiking around camp in the evening at 8,000 feet on the shoulder of mighty Mount Saint Elias, if I would find sea shell fossils similar to those scattered above Dollar Lake in the eastern Wallowas?
Oregon’s Wallowa Mountains are located in the far northeastern corner of the state about a seven-hour drive from Portland via Interstate 84 and State Highway 82. Picturesque Joseph, Oregon — known for its robust bronze sculpture artistry — sits at the foot of the mountains and is a popular last taste of civilization before heading into the Eagle Cap Wilderness.