Some years ago I posted a blog entry about photos of glacial erratic boulders on Olmsted Point in Yosemite National Park. Well, I was recently there and got a few more. Glacial erratic boulders are so named because they are erratic (i.e., differ materially from the naturally occuring stone nearby) and they were deposited by slow-moving glaciers, sometimes after having been moved a considerable distance (e.g., tens of miles) from their place of origin. The boulders are carried by the glacier and then either fall off the side of the glacier as it slowly slides along, or are simply dropped in place if a glacier melts away. Olmsted Point, high above Tenaya Canyon, is a great location for seeing glacial erratic boulders. The same glaciers that sculpted nearby granite monoliths Half Dome and Cloud’s Rest, seen in the background of one these photos, also left behind many glacial erratic boulders on the rim of Tenaya Canyon when it passed by.
Glacial erratic boulders atop Olmsted Point, with the massive granite monoliths Half Dome and Clouds Rest in the background. Erratics are huge boulders left behind by the passing of glaciers which carved the granite surroundings into their present-day form. When the glaciers melt, any boulders and other geologic material that it was carrying are left in place, sometimes many miles from their original location.
Image ID: 23264
Location: Yosemite National Park, California, USA
Glacial erratic boulders atop Olmsted Point. Erratics are huge boulders left behind by the passing of glaciers which carved the granite surroundings into their present-day form. When the glaciers melt, any boulders and other geologic material that it was carrying are left in place, sometimes many miles from their original location.
Image ID: 23265
Location: Yosemite National Park, California, USA
See also: Yosemite National Park photos.
Keywords: glacial erratic boulder, geology, granite, Olmsted Point, Yosemite National Park, glacier, rock, stone.
