I think the term to describe these formations is 'pahoehoe', but I do not know for sure (if any of you out there reading this do, please e-mail me and let me know). It was interesting to walk over these formations since the rock is actually only an inch or two thick with hollow spaces underneath. There is a kind of tinking sound that you can hear with each step.
Location: Jordan Craters, Malheur County, Oregon
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Journal: 11 July 2001: Owyhee Canyon and Jordan Craters