Wallowa Mountains

Located in northeastern Oregon, the Wallowa Mountains are a beautiful alpine mountain range, dubbed the “Swiss Alps of Oregon”. Containing numerous peaks above 8,000’ in elevation and capped by the 9,838’ Sacajawea Peak, the Wallowas are a marquee destination for all kinds of outdoor recreation, including, but not limited to, hiking, camping, backpacking, mountain climbing, paddleboarding, fishing, and hunting.

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Geologically speaking, these mountains are quite unique and distinctive from most of Oregon’s ranges, as they are chiefly composed of plutonic and metamorphic rock, as opposed to the volcanic bedrock of the majority of Oregon’s mountains. The rock unit central to the Wallowas is a Cretaceous-aged granite known as the Wallowa Batholith, which Geologists interpret as a very specific type of pluton known as a stitching pluton. Stitching Plutons are generally defined as igneous intrusions that intrude across different terranes and appear to “stitch” them together. More specifically, they intrude and obscure the contact between a terrane and an adjacent rock unit. In the case of the Wallowas, the Wallowa Batholith has “stitched” the Triassic aged Wallowa and Izee Terranes together.

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The aforementioned Wallowa Terrane is a melange of volcanic and sedimentary rock dating back to the Triassic Period, remnant of an ancient island arc formed in the Pacific Ocean and accreted onto the margin of western North America as the Farallon Plate subducted underneath the North American Plate roughly 200 million years ago. The Wallowa Terrane is one of numerous exotic terranes- pieces of Earth’s crust that have merged with another landmass that have entirely separate and unique geologic histories and origins, that have been accreted onto the western edge of North America. The Izee Terrane is another such example of an exotic terrane that outcrops in the Blue Mountains of northeastern Oregon. The Wallowa Terrane is chiefly composed of basalt and limestone, suggesting it originated as an island arc in the Pacific Ocean before it was sutured onto the North American continent via subduction. The Wallowa Terrane was accreted onto North America during the early Cretaceous Period, roughly 150-120 million years ago, and the Wallowa Batholith dates back to that time as well, evidence of the fact that it is a stitching pluton. 

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At the top of the highest peaks in the Wallowa Mountains, Miocene aged Columbia River and Grande Ronde Basalt can be found, suggesting that the vast lava flows from 17-6 million years ago, when the Columbia River Flood Basalts were active, covered the Wallowa Mountains, at least in part. This raises an interesting question: how can lava flow from fissures in the earth up to the top of a mountain range? The answer is, it can’t. So what does this mean? This means that the Wallowa Mountains, as a mountain range, is younger than the Columbia River Flood Basalts. It is important to note that rocks in the Wallowas are significantly older, but the mountain range itself is younger. The origin of the uplift of the Wallowas is a very interesting geologic story. Uplift of the Wallowas began during the eruptions of the Columbia River Basalt Group, and lava flows are thinner over the Wallowas than they are at lower elevations in the area, suggesting that what would eventually become the Wallowas was at least somewhat uplifted during this time. Geophysical studies of the upper mantle beneath the Wallowa Mountains show evidence of high seismic velocities, most likely caused by magmatic depletion of the mantle due to the massive eruptions of lava of the Columbia River Basalt Group. This then caused the crust and mantle under what would become the Wallowas to be more buoyant, due to such voluminous extraction and depletion of basaltic magma, thus beginning to uplift the mountain range during the eruptions of the Columbia River Flood Basalts. This is all outlined by mathematical modeling and geophysical data of the area.

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As the Wallowa Mountains began to uplift during the Miocene due to depletion of the mantle underneath them, the crust in the area began to be torn asunder, generating range-bounding Normal Faults on both sides of the range. On the northern margin of the Wallowas, the Wallowa Fault cuts Columbia River Flood Basalts and Quaternary Alluvium, continuing to actively uplift the range today. Roughly 7,000’ of vertical offset exist on this fault, and the Wallowa Fault is capable of generating a Magnitude 7.1 earthquake. As aforementioned, the Wallowa Fault is still active today.

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During the last ice age, numerous glaciers existed in the Wallowas, carving out cirques, U-Shaped Valleys, moraines, and other glacial landforms. Wallowa Lake is remnant of the last ice age, dammed by a large moraine- a mass of rock or sediment carried down and deposited by a glacier, typically as a ridge, that dates back to the Pleistocene Epoch.

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From an ecological standpoint, the Wallowa Mountains are very interesting and unique as well. Lower elevations in the range support Ponderosa Pine, Douglas Fir, Grand Fir, and Lodgepole Pine, while Western Larch and Engelmann Spruce dominate middle elevations. Above 7,000’, Subalpine Fir and Whitebark Pine dominate, while Quaking Aspen, Willow, Alder, and Rocky Mountain Maple dominate riparian areas. In terms of fauna, the Wallowas are home to Mule Deer, Elk, Mountain Goat, Western Chipmunk, Columbian Ground Squirrel, Golden Mounted Ground Squirrel, American Badger, Mink, Pine Marten, Skunk, River Otter, Bobcat, Mountain Lion, Coyote, Grey Wolf, Red Fox, and Black Bear, among other species of mammal. Clark’s Nutcrackers, Western Scrub Jay, Osprey, Red-Tailed Hawk, Bald Eagle, Peregrine Falcon, Great Horned Owl, and a plethora of songbirds dominate the skies, whilst Kokanee Salmon, Rainbow Trout, Lake Trout, Brook Trout, and Smallmouth Bass dominate the waters of the Wallowas.

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Some interesting areas worth visiting in and around the Wallowa Mountains are the town of Joseph, Wallowa Lake, the Wallowa Lake Tramway, and any of the several hikes in the range. Backpacking Eagle Cap, one of the higher peaks in the Wallowas (9,577’), is iconic, as is hiking up to Ice Lake or up the highpoint of the Wallowas, Sacagawea Peak (9,838’). You can’t go wrong in the Wallowas, and the mountains have so much to offer for both the intrepid adventurer and the weekend explorer. One thing to note about the Wallowas is that hiking from the Wallowa Lake Trailhead requires a permit- but it is free, you simply fill it out at the trailhead, and requires no online or prior planning. 

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As beautiful as the Wallowas are, they are equally as remote- which perhaps adds to their mystique and beauty. The town of Joseph is the gateway to the Wallowas, and it lies 4 hours from Boise, 5 ½ hours from Portland, and 6 ½ hours from Seattle. If you’re planning on going to the Wallowas, it would perhaps be in your best interest to spend the night in the area. The towns of Joseph and Enterprise are at the foot of the mountains, and both offer lodging accommodations. Additionally, camping is plentiful in the area, but be aware that the Wallowas are not only bear country, but also wolf country.