Very large wrinkles in schist in the northern part of the area. Custer County, South Dakota. 1963.
Dates
Date Taken
1963
Summary
Very large wrinkles (forming stairway in photograph) in schist in the northern part of the area. The main schistosity and the bedding strike north 60 degrees west and dip 50 degrees southwest (parallel to the crests of the wrinkles). A second schistosity is developed locally that strikes north 67 degrees east and dips 40 degrees northwest (parallel to the axial planes of the Wrinkles). The geologic pick rests on a sinuous quartz vein about 1 inch thick that follows the crenulations of wrinkles. The knobby character of the schist is caused by quartz-sillimanite knots. Custer County South Dakota. Published in U. S. Geological Survey Bulletin 1142-E. 1963.
Summary
Very large wrinkles (forming stairway in photograph) in schist in the northern part of the area. The main schistosity and the bedding strike north 60 degrees west and dip 50 degrees southwest (parallel to the crests of the wrinkles). A second schistosity is developed locally that strikes north 67 degrees east and dips 40 degrees northwest (parallel to the axial planes of the Wrinkles). The geologic pick rests on a sinuous quartz vein about 1 inch thick that follows the crenulations of wrinkles. The knobby character of the schist is caused by quartz-sillimanite knots. Custer County South Dakota. Published in U. S. Geological Survey Bulletin 1142-E. 1963.
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