Obsidian hydration dates glacial loading?
Friedman II, Long WD, Pierce KL, Obradovich JD. 1973. Obsidian hydration dates glacial loading?. Science. 180(4087):733-734
Three different groups of hydration rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming. The average thickness of the thickest (oldest) group of hydration rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average hydration rind thickness of 14.5 and 7.9 micrometers. These later two hydration rinds compare closely in thickness with those on obsidian pebbles in Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow.
- Type
- Journal Article
- Authors
- Friedman, I; Long, William; Pierce, Kenneth; Obradovich, John
- Units
- YELL
- Keywords
- Geology, Geomorphology, Glaciers, Ice, Isotopic Dating, Obsidian Cliff, obsidian hydration dating, Rocks