By Clyde E. Gilbert, Chief Ranger
The all-time record for travel in Crater Lake National Park set in the travel year 1941 was broken on the 20th of August. At the end of the travel day on the 20th, 83,319 cars and 274,592 people had visited the park. The previous record was 82,466 cars and 273,564 people.
Redcloud Rock Slide
By L. T. Grose, Ranger-Naturalist
At 11:10 A.M., July 15, a tremendous blast, followed by a rumbling noise, resounded around the caldera walls. It sounded much like a series of thunder claps, and evidently, everyone thought it to be thunder from a lingering dark cumulus cloud overhead. Actually this "thunder" was the collapse and slide of a section of Redcloud Cliff. A study of the slide is significant because of its being typical of the larger rock slides and mass erosion within the caldera.
A slab, estimated to be 250 x 200 x 8 feet, of the older dacite flow under and immediately to the south of the V-shaped mass of Redcloud Cliff spawled off and slid 9/10 of the way down to the lake shore. One third of the largest blocks were carried farthest by their momentum, but none of them reached the lake. Slight sorting of the debris is evident on the lower portion, the heavier blocks being followed by increasingly smaller fragments. The original, underlying talus was pushed to the shore, extending the fan to the water's edge. Therefore, the total rock slide continued 1,000 feet from the base of Redcloud Cliff to the water's edge. Most of the larger fragments came to rest approximately half way down, and a smaller portion were stopped by the bottle-necking effect of big and little Castle Rock formations. In these higher portions there is little or no evidence of sorting.
The slide fragments came to an unstable rest at the maximum angle of repose, in this case of angular blocks, 43 degrees. It is believed that this angle is reached only in the upper third, and that the slide curves, as the lower portion grades down to approximately 38 degrees. This upward curving is characteristic of new, unstable, and active slides. The lower slide area is semi-safe to climb over due to frictional stabilization of detritus, but the larger rocks in the upper portion are delicately balanced. Prior to this recent slide the Redcloud talus slope was not at the maximum angle of repose, otherwise more than the total additional weight of new slide material would be carried into the lake.
Distortion and dilation transformed the dacite slab into fragments ranging from 1,000 cubic feet down to rock dust. On top of the larger blocks there was loose, fresh rock powder, a characteristic of very recent, large rock slides. Many hand-sized fragments appeared integrated and competent, but crumbled easily under fist pressure. A slickenside appearance is quite obvious on the adjacent andesite spurs, however none of this resistant rock broke loose. Amazingly enough, little Castle Rocks remain none the worse for wear, in spite of much rock battering over them. Small amounts of pumice slide with the main block, but the remains of this were crushed into dust.
The causes of the larger rock slides inside the rim are a number of interesting natural processes. Redcloud Cliff faulted downward on a nearly vertical plane which affords maximum gravitational pull. Water, directly and indirectly, has helped disintegration and decomposition within a series of cracks, mostly from the top downward. Water seeped from Cloudcap dome into tension cracks near the rim and froze. Seasonal and diurnal temperature changes, alternate freezing and thawing, greatly accentuated frost wedging, which can be an effective cause of spawling. Most likely by the middle of July the ice within the cliff melted sufficiently to hold the rock together no longer. The rock collapsed after the cementing ice had melted away.
A clayey surface was seen on some of the larger rock fragments. This suggests the slow decomposition and decay of the rock itself, or the washing in of volcanic dust, either one being a function of water and ice. The rock face fractured quite evenly along semi-columnar joints. No oxidation of iron or water seepages can be seen. The uniformly light tan of the cliff face indicates hydration as a mode of decomposition. This process produces a swelling of rock parts, allowing moisture to penetrate until some decay is effected. In conclusion, the primary cause was the increasingly powerful action of frost wedging, and secondarily, the expansion and decay due to hydration.
The newly exposed cliff remains very unstable, as well as the talus slope beneath. Fragmental bits are still constantly falling off. It will be interesting to watch -- from a distance.
The Uniformed Naturalists Of 1947
By Dr. G. C. Ruhle, Park Naturalist
Ranger naturalists are scientists carefully selected not only for their intimate knowledge of nature and its ways, but also for their enthusiasm and ability in aiding others to know it as well. Curtailed and finally abolished during the war, naturalist services were resumed in a modest measure in the park last year, upon the return of the park naturalist after four years of service in the Navy. Every important naturalist service which was offered before Pearl Harbor, was restored to the program this year. The uniformed men on the staff number eight.
Dr. R. R. Huestis, dean of naturalists in the park, returned to tell in his inimitable fashion about private ways and doings of mantled ground squirrels and a host of lesser folk. He is professor of biology at the University of Oregon during its regular season. Mrs. Huestis is the obliging pianist for naturalist pow-wows in the Community House each night.
Coming to the park last year from the foxholes of Okinawa, ex-Marine Orthello L. Wallis of Oregon State College is conducting a park survey of stream fish and fishing, as well as having his share of talks, conducted trips, and contact duties. While his fellows were fighting off boredom between annoyances by the enemy, Mr. Wallis made a collection of trap door spiders on Okinawa, and has published a scientific paper on them. To his efforts, also, is due the assembly of this issue of Nature Notes. His wife, Nancy, has prepared the originals of illustrations used.
It took considerable persuasion to bring Walter S. Vincent, Jr., from his laboratory at Oregon State College, since he boasts a brand new pair of twins, whom he hesitated exposing to the wilds and hardships of Crater Lake forests. With his choice of field in zoology, a good background in botany, and a prying interest in what goes on in ponds, pools, and puddles, Mr. Vincent has an appealing and authoritative fund of information for park visitors. When it is his night at the "Comhouse", Mrs. Vincent helps with the entertainment. Mr. Vincent was with the Army Medical contingent in the Pacific Theatre of war.
Fresh from Osborne Botanical Laboratory at Yale, ex-Marine Gordon P. Walker specializes in cellular botany, but while in the park has interested himself in plant parasites and saprophytes. Mr. Walker shared the brunt of the ordeal of landing operations at Iwo Jima, being attached to the Fourth Division.
Lucius T. Grose is a geologist from the University of Arizona, at which institution he was associated with Eddie McKee, popular and efficient park naturalist of Grand Canyon National Park in the thirties. A navy man, ex-aerographer's mate Grose served on fighting flattops, including the Essex, Hornet, and Hancock. He was with task force 39 during the bombardment of Japan.
Norman Doyle is an aeronautical major at San Jose State College in California and a student of ex-ranger naturalist-geologist Wayne Kartchner. He spent three years with the air arm of the Navy, being pilot of a PBM on patrol bombing duty of the Philippines, Okinawa, China, and Japan.
Two junior ranger-naturalists complete the uniformed staff, and are giving valued help in information rangers and leaders of occasional trips. Thomas C. Matthews of Portland is a forestry student at Oregon State College. He has had previous outdoor experience in the Wallowas and in Alaska. Donald G. Findlay of Eugene, Oregon, is a student of ex-ranger naturalist Dr. Warren G. Smith, head of the department of geology and geography at the University of Oregon. He served as any army air cadet during the war.
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