The Geology and Petrography of Crater Lake National Park, 1902
Introduction
By Joseph Silas Diller
EXCURSIONS ABOUT CRATER LAKE.
By far the most impressive and, to the geologist, most important trip about Crater Lake is by boat front Eagle Cove along the western and northern shore of the lake to Cleetwood Cove and Rugged Crest, returning by way of the crater capping the cinder cone in Wizard Island. It can be made in a day, but may require hard rowing. The rare opportunity of travelling about in the interior of a volcano could hardly be anything else than intensely interesting. The descent by the trail and cruise along the shore disclose the alternately overlapping sheets of andesitic lava and conglomerate of which the rim is composed. These are cut by dikes—a prominent one is at Devils Backbone, and smaller ones occur beneath Llao Rock. Some of these are andesite, but others dacite. The great flow of Llao Rock, over 1,200 feet thick in places and tapering to thin edges on the sides, is dacite. It is younger than the andesites of the rim and fills an old valley. At Pumice Point layers of pumice and streams of dacite overlie platy andesite which was glaciated before the dacites were erupted, and at Cleetwood Cove is seen the inflowing dacite from Rugged Crest and the caved-in lava tunnel to the northward. The latest flow of the rim is the tuffaceous dacite along the northeast crest from Pumice Point to the Wineglass, but later even than this is the excellent example of a little volcano which forms Wizard Island, with its cinder cone capped by a perfect crater summit, marking the vent from which the cinders were blown. From the island and the boat the glacial notches in the southern rim of the lake and the dacite flows of Cloud Cap and the eastern rim may be seen to greatest advantage.
The most instructive day’s walk from the rim camp (Camp 1 on map), but a rather hard one, is along the western crest to Llao Rock. Glacial striae are best displayed along this portion of the rim. Andesites are exposed all the way to the Llao Rock flow, which near the edge may be examined both above and below. The inflow of Cleetwood Cove is clearly visible from a distance, and an excellent view of the crest of the Cascade Range may be obtained.
Those who may wish to make a camping trip around the lake are advised to take a pack train and devote a number of days to the trip, as the distance around the crest of the rim is over 20 miles and over much of the route traveling is difficult. There is no definite horse trail around the rim, but a practical pack route, with camping places indicated by numbers, is marked upon the map (Pl. I).
The canyon of Sun Creek is difficult to cross, as its western wall is precipitous. Near the notch there is pasture and good camping, but lower down, where the trail crosses, feed and water are scarce. At Camp 2, on the west fork of Sand Creek, there is plenty of both. Camp 3 has many attractions besides the fine firs and flowers. The great cliffs are inspiring, and the rustling of numerous little cascades gives a life to this enclosed camp that is not to be found elsewhere about the lake.
The ascent of the east side of Sand Creek Canyon is steep and somewhat difficult, but the fine views of the lake from the eastern rim in the morning abundantly pay for the special exertion necessary to attain them.
Camp 4 has some pasture and snow water. Beneath the large cliffs just north of the camp water was obtained for the animals. To the northeastward about 3 miles, in the line of the canyon heading at Cloud Cap, are fine springs and a cascade 50 feet in height. There is considerable pasture here, but on the whole the place is less inviting for camping than locations close to the crest. From this camp the descent to the lake may easily be made at the “wine-glass”-shaped slide of Grotto Cove.
At the head of Cleetwood Cove the crest is very rugged and somewhat difficult to cross with animals, but elsewhere travel along the northern rim of the lake is easy. Near the foot of Red Cone there is good camping by a spring. At many points along the lower slope of the western rim of the lake there are fine camps, plenty of grass, wood, and water, but in the past the sheep have greatly injured the pasture. Near the crest cliffs and rough talus slopes make traveling difficult and dangerous for animals. The easy and safe but longer route lies west of the cliffs to Camp 6, which is the main pasture camp of the region, with fine water.
