Skip to main content

TABLE MOUNTAIN: Columbia River Gorge Geology

In a previous blog entry, Bridge of the Gods (http://thenarrativeimage.blogspot.com/2007/03/bridge-of-gods.html), I noted that some geologists have posited a link between a landslide that likely occurred in the 1200s and local myths/legends describing a land-bridge across the Columbia.

Current, apparently misnamed, Bridge of the Gods.

John Eliot Allen, author of The Magnificent Gateway, writes, “The lobe of the latest (“Cascade”) slide covers about 5 ½ square miles. It diverted the river a mile to the south, and contained a dam long enough, in all probability, to give rise to the Indian legend of the “Bridge of the Gods”

Mr. Allen describes the unstable geologic situation like this. “Heavy Grande Rhone Basalt-flows cap Greenleaf Peak and Table Mountain, resting upon 1000 feet of weak, clay bearing Eagle Creek sediments.”

The trail I took to Table Mountain starts at the Bonneville trail head. It’s on the Washington side of the river across the highway from the Bonneville Dam’s visitor center parking lot. You can pick up a parking/forest pass at a Chevron station a couple miles west of the trail head (Five dollars for a day pass).

At the east end of the trail-head parking lot, find the Tamanous trail sign and proceed about a half a mile until you merge with the Pacific Crest Trail. A sign at the intersection almost counter intuitively points North and South. Go north, ultimately, along the Pacific Crest trail, though it will feel an awful lot like you are really going west. Whenever you come to an intersection, be sure you see the little metal Pacific Crest Trail diamonds posted in the trees when you resume your walk or you may be off track.



Heading down the trail toward Gillette Lake, I noted that were it not for the moss, you would think the landscape was still rolling. While some carbon dating results put the landslide event at about 1260 A.D., other geologists have attempted to date the slide by measuring lichen growth.


Gillette Lake has some nice camping sites and appears to periodically host beavers. There are remnants of lodge and dam building activities. I’m inclined to describe the color of Gillette lake as a green not found in nature, but that apparently can’t be accurate.


A little bit past Gillette Lake, the trail opens up onto what may be an old logging road and a clear cut area that affords a good view of the sheared away face of the mountain. This image shows Table Mountain as it appeared this year on March 3rd (left) and again on April 1st (right).



A former trail to the top of Table Mountain has been closed due to erosion and other environmental concerns. A posted sign encourages you to continue another half mile to this newer access point. If the trail so far has been a medium ‘5’, it is about to become a “9” and for old out of shape fat men, maybe an “11”.


Later on, there will be the additional psychological challenge of exposure to sheer drop-offs. I had to shield my eyes with my hands – like blinders – to keep focused on where I was placing my feet.



From this vantage point, you can see how the river bends to the south behind Bonneville Dam.


From the summit, looking east up the Columbia River gorge.


This ridgeline leads to the top (The point) of the sheer face of Table Mountain



In retrospect, I’m not sure it is a good idea to get this close to the edge of an unstable mountain with a demonstrated propensity to slide.



I thought it was hard going up the mountain, but my knees had a surprise for me when I started back down. Fortunately, I got off the rocky dangerous part well before dark. Limping past Gillette Lake on the way out, I was thankful I had my flashlight and my bag of survival gear – just in case (about 15 1/2 miles round trip).

Comments

  1. Beautiful images

    -Scott at Wallhogsh

    ReplyDelete
  2. Breathtaking, Scott.

    And I love the way you showed the difference a month makes on Table Mountain.

    ReplyDelete

Post a Comment

Popular posts from this blog

John Day River: Thirty Mile Creek to Cottonwood Bridge

"Ever since the creation of the world his invisible nature, namely, his eternal power and deity, has been clearly perceived in the things that have been made. So they are without excuse;" -Romans 1:20 "I'm not so sure about that, but whether or not we all make it through these rapids alive, I'm confident the grading criteria will be fair." -  Scott "Get ready to explore your world without boundaries." -  Wilderness Systems Owners Manual Sunrise found us on the outskirts of Wasco, high on the Columbia Plateau, our 3 vehicle convoy speeding through golden fields of wheat on toward Condon and then West to a 7:30 AM meeting with a rancher who would provide us a private launch site to the John Day river and also execute our car shuttle.   Startling verdant fields, free of the vestiges of irrigation, belied narratives of drought that punctuated the news. The fresh born morning, still cool to the senses, felt like the fledgling hours of a

Miller Island Expedition: Columbia River Ghost Cult

My brother Fred sent me a checklist of things he didn’t want to forget for our second attempt at a Miller Island Expedition. Foil pans Steak Beer or whiskey/tequila Bacon Shovel TP Bug spray Homebrew Ghost repellents Scouting Miller Island from the Lewis and Clark Highway (Washington side of river) “Ghost repellents?” I asked. Well, it turns out that Fred had been doing some research and found an old article from American Anthropologist by Wm. Duncan Strong called The Occurrence and Wider Implications of a “Ghost Cult” on the Columbia River Suggested by Carvings in Wood, Bone and Stone. The article, written in 1945, revealed that bone carvings depicting figures with prominent rib cages, a symbol of death, were found in old cremation pits on Miller’s Island. Excerpts from the article: “It can be shown that among these peoples there was an old belief in the impending destruction and renewal of the world, when the dead would return…” “One of the most striking fea

Test Paddling the Tarpon 160 (finally)

The problem with 'objectivity' is that it's usually 'subjectivity' cleverly disguised as objectivity. I've wanted the Tarpon 160 ever since I saw it sitting in the rack at the kayak shop. However, I'm trying to take the universal advice of the broad community of kayakers who suggest that choosing a kayak is a personal choice based on how a particular boat fits one's body and objectives, and so, going through the motions of due diligence, I've finally come to the day when I actually get to paddle my dream boat. It doesn't escape my attention that I seem to have a Wilderness Systems' bias. The first kayak I ever sat in was their 12 foot plastic Pungo which delivered me down the Sandy River without making me a candidate for the Darwin Awards. The first kayak I ever bought (so far the only kayak I ever bought) was their Tsunami 125 which has, over the last eight years, patiently taught me everything I know about kayaking except for tha