Dome Rock and the continuing trials of Jo, the Adventure Civic

Dome Rock Hike: 10/10 would hike again, magnificent view

Drive to Dome Rock north trail head: 10/10 would NOT attempt again in a 2001 Honda Civic

I had originally planned to hike the 10-mile round trip trail from the Detroit Lake information center up the ridge to Dome Rock, but the ranger at Detroit Lake State Park was quick to discourage me. He suggested that it would be much easier to take the Forest Service road to the northern trailhead and just do the prettiest 3 mile section along the ridge top. Sure! Why not?

18% average slope on gravel roads is why. Having to stop and restart my crotchety old car multiple times on said 18% slopes to move away the fallen rocks so I could get clearance is another good reason.

Luckily the beauty of the hike brought my blood pressure back down again within a mile or so. The trail wound though firs, maples, and thimbleberries (snack time!) along the ridgetop above Tumble Lake.

Map of Dome Rock trail

Map from Willamette National Forest USFS website for trail 3381

Directions to the Tumble Creek North Trailhead can be found here on the USFS site. They aren’t kidding when they say “up steep mountain roads”.


At the top of Dome Rock, selfie with Tumble Lake!


View of Mt. Jefferson and the Three Sisters from the top of Dome Rock.

I was hiking in the Western Cascades, which form the more eroded volcanic predecessor to the striking peaks of the younger High Cascade mountains. Magma rising from the subducting Farallon plate created both zones of the Cascades, but the two stages of that subduction made them distinct. Between 35 and 8 million years ago the plate sank under North America at a slightly steeper angle, resulting in the location of the Western Cascades. Around 7 million years ago that angle became shallower, which moved the depth at which the magma rose off of the melting plate to location further east. (Devis 2013)

Inkedwestern vs high cascade Miller page 110_LI

Figure from page 110 of Marli B. Miller’s classic “Roadside Geology of Oregon” – the area of Dome Rock  is circled in yellow

change in subduction zones Miller page 113

Figure also from “Roadside Geology of Oregon”, page 113, showing how the change in subduction angle influenced the location of volcanoes further inland.

All the classic cone-shaped volcanoes of the Cascades such as Mt. Jefferson, the Three Sisters, and Mt. Hood are part of the High Cascades. In contrast, a few more million years of exposure to rivers and glaciers created the more subdued landscape of the Western Cascades. Any volcanic cones from that era have long been ground down to their roots.


Standing in the Western Cascades, looking at Mt. Jefferson in the High Cascade mountains. Photo taken during one of my stops to move rocks off the road…

Dome Rock itself is one of those “roots” – an isolated piece of 10 million to 17 million year old andesite where newer magma punched through a 30 million to 17 million year old area of tuff (cemented volcanic ash) and basalt. (Walker, G.W., and Duncan, R.A., 1989) It’s relative toughness meant that it withstood the 10 million years of weathering since its formation better than the surrounding formation’s softer tuff with basalt, creating the bare knob with spectacular 360 degree views.


Andesite near the top of Dome Rock… next time I’m hiking with my rock hammer.

Jo’s engine may have nearly overheated on the way up, but at least I didn’t have to use the engine at all for seven miles on the way down. After creeping back down the forest service road using a combination of second gear and brakes, I stopped at a peaceful little day use area along Frenchman Creek to eat my lunch. Judging by the size of the boulders in the creek bed, the stream hasn’t always been so tranquil!


Frenchman Creek day use area, about 1.5 miles north of the intersection with Hwy 22

Zach Urness of the Statesman wrote a helpful article on the Dome Rock/Tumble Lake hikes with more information about the lake and its campsites. I didn’t go down to the lake this time, but maybe next trip.

With all the time that skipping the extra 7 miles of the hike saved me, I stopped by Marion County’s Niagara Park on the North Santiam on the way home. My phone was dead, so no pictures this time, but if I’m by there again I’ll definitely stop to take some. The site was ambitiously called “Niagara” by hopefuls in the late 1890s aiming to build a dam where the Santiam is funneled through a 4-foot-wide crack in the underlying rocks. The dam failed repeatedly and they gave up in 1912, leaving a park with picturesque ruins. About a half-mile up the stream from the failed dam lies a  misshapen mound of rocks eroded into a perfect picnic spot and place to cool your feet off in the river.

I was sorry to have to leave the parks and head back home… and on the way back I got Jo a well-deserved car wash.


My sister posing with Jo the Adventure Civic on another trip that I’ll be blogging about soon!

One thought on “Dome Rock and the continuing trials of Jo, the Adventure Civic

  1. Pingback: Sisters visit South Sister (and Green Lakes) | Blue Marble Earth

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