41-3 Volume 19 – 1953

Continued from page two

Climb Mount Thielsen!

By Clifton E. Peterson, Ranger Naturalist, 1952

Mt. Thielsen
Mt. Thielsen is on the right. Photo by James Richards, Seasonal Ranger, 1952.

Mount Thielsen, the magnificent pinnacle seventeen miles NNE of Rim Village, always excites the interest of the visitor to Crater Lake National Park. This pointed spire, commonly compared to the Matterhorn in Switzerland by the European visitor, even though only 9,173 feet in elevation, beckons the adventurous.

Mount Thielsen rests on a base of rocks uplifted from the ocean about 60 million years ago. Covering this, and rising to an elevation of 3-4 thousand feet, is the same kind of basalt that makes up the Columbia River plateau. The next several thousand feet are composed partially of lavas which may be referred to as either basalts or andesites, the remainder being pumice and scoria. Forming the mass of the barren pyramidal summit is a compact cinder-like material which has been invaded by many basalt dikes. Through this tuff cone projects the dark lava plug which forms the sharp projecting peak of the mountain.

Mount Thielsen, like all volcanoes, is thus composed of materials thrown up by its own eruptions. Intermittent eruptions began some 25 million years ago and ceased sometime during the last of the Great Ice Ages, probably about one million years ago. At that time the elevation of the summit was in excess of 10,000 feet. The ponderous, moving sheets of ice upon Mount Thielsen’s slopes ground away the top until, with the gradual warming of this continent, the glaciers passed away.

The Skyline Trail to the summit of Mount Thielsen begins near the trailer camp just off Hwy. 209, at the SE corner of Diamond Lake. The five mile trail to the summit of Mount Thielsen fades as the solid rock near the top is reached, but beyond this point the best route approaching the spire from the south should be apparent. Except for the last 100 feet, which necessitates climbing upward at an eighty degree angle utilizing crevices in the rocks as support, this trip should present no problems to the average hiker using common sense. No ropes are needed. The hike to the top will take 2-5 hours.

For the safety of hikers, it is desirable for them to state, on forms available at the Forest Ranger Station 1.4 miles north from the trail entrance along the Diamond Lake road, their intention to climb Mount Thielsen. At the end of the hike they should return to the Ranger Station and note the successful completion of the climb on the same form.

On the morning of August 8, 1952, our party of six started from the foot of the Skyline Trail, packing canteens and lunches. The meadow at the start of the trail changed rapidly to the dense forest of lodgepole pine which covers all the lower slopes of the mountain. The few small open areas beside the trail were filled with flowers. After a slight downward slope across the now dry Camp Creek, the trail became steeper. From the deadened tramping of feet on the dry pumice slopes little clouds of dust arose. We stopped to rest, discussing the natural history unfolding before us. Juncos and western tanagers perched above us.

We started upward again. Intermixed with the lodgepoles were a few ponderosa pines, western white pines and firs. More and more mountain hemlocks were noted; the elevation was becoming too high for the lodgepoles. Small pieces of pumice covered the ground, replacing the pumice dust. More basalt was seen.

We passed across relatively open pumice slopes. Trees were fewer, and most of these were white-bark pines. Then the pumice slope became barren of trees, except for a few small scraggly white-bark pines struggling in a sterile and as yet undeveloped soil. But sulphur flower, Newberry’s knotweed, lovage, alpine false dandelion, varied-leaved phacelis and other flowers brightened the area. Each step forward was partly lost by sliding backwards, due to the softness and slope of the trail.

Light colored, fragmented lava gradually replaced the pumice and the slope increased. Here visible plant life was at a minimum. We passed by dark, horizontally-layered remnants of the old tuff cone projecting high into the air. To the south and southeast the tuffs dip steeply for the most part. This material gave a better foothold for climbing than was available upon the fragmented lava.

A depressed area in the sloping tuff to the west of the spire, cut by water from melting snows, was heavily populated by the golden long-leaved arnica, bleeding heart, Davidson’s penstemon, long-stemmed penstemon, lovage, and, more rarely, Lewis’ monkey flower, Jacob’s ladder and five-finger.

As we neared the top, rests were more frequent. We approached the base of the summit pinnacle from the south–the only readily accessible route to the top. A few dwarfed white-bark pines grow near the base of this last obstacle to a successful climb.

The last 100 feet was almost straight up, and it was necessary to pull oneself up by handholds in the rock. I was carrying the pack containing the lunches. Trying to hug the bare rock for that last hundred feet, the feeling of being pulled off-balance and away from the rock by the pack, the strange feeling at looking off into a void from this precarious position — well, nothing can quite compare to it.

The view from the top was spectacular! To the north we saw a storm-lightning and thunder and drenching rainfall. Westward, the slopes of Mount Thielsen fall off toward shallow Diamond Lake, lying 4,000 feet below. Beyond the lake is the broad-shouldered volcano, Mount Bailey. Eastward, the slopes of Mount Thielsen lead gradually down to the broad basaltic plateau of central Oregon and across the marshlands where graze 150,000 cattle. To the north, the Three Sisters are easily visible, and to the south, across Pumice Desert, is the grandeur of the rising slopes in which nestles Crater Lake. Fully one-third of Crater Lake is visible beyond its precipitous rim. Far, far to the south, the snow-capped peak of Mount Shasta is dimly seen through the slight haze, 140 miles away in California.

The top of Mount Thielsen is a small area about 9×14 feet. This is where we ate our lunch. The wind was blowing with that eerie sound to be heard around barren rocks in high places. To the NE and ESE of this platform are sheer drops of 1,600 feet into barren valleys containing masses of glacial debris. These valleys were formed as glacial cirques ages ago. Far down, 1,900 feet below, mighty springs can be seen gushing from the side of the valleys, the waters of which wend their way across forested valleys, eventually to reach the Pacific.

We prepared to leave. All around as far as the eye could see were foresee and lakes and mountains, certainly defying description, almost defying belief. Except for the very intriguing first portion of the descent, the trip down was uneventful.

For the visitor to Oregon, the climb up Mount Thielsen will provide a memorable experience.


Williams, Howell 1933. Mount Thielsen: A dissected Cascade volcano. University of California, Berkeley. Bulletin of the Department of Geological Sciences 23: 195-214.