Johnsondale Potholes

December 28, 2003


Provided and copyright by: Tom McGuire
Summary author: Tom McGuire

Inquiry is at the heart of science; for scientists as well as students. This group of holes is on a granite outcrop in the southern Sierra Nevada Mountains at the former logging camp of Johnsondale. I do not know the origin of these holes. Such open issues are sometimes called discrepant events.

Two possibilities come to mind. They may be potholes caused by stream erosion. But they are numerous (about 20 of them) and uniform in size and shape. Native American matates, holes in rock used as natural bowls for grinding grain, are common in the southwest. (The shards of minerals in their bread products sometimes caused excessive tooth wear.) But these are quite deep and small. What do your students think?

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