A much belated Happy Birthday to Monte and a hearty "Attagirl" to Julie for the strong comeback from knee replacements.
Regarding the rounded rock (quartzite?) in the Owens Valley:
There are a plethora of geomorphology studies concerning the Eastern/Southern Sierra and DV. Seems particularly interesting because normal evidence of very young events has been deformed by ongoing tectonic developments. As seems to be the case just about everywhere in that part of California and adjacent portions of Nevada, one can find everything from Precambrian basement rocks well over a billion years old to mappable sedimentary deposits just a few thousands of years old. What a laboratory!
There are some curious aspects of the outcrops decorated by the ancients' "pecking". One is that quartzite would require some pretty hard tools (made of other rock) to be "carved" as the pictures show. With so much of the artwork seeming to represent painting exposed surfaces with natural pigments, the amateur archeologist might assume that artwork carved into quartzite outcrops to be much the exception. Chipping fresh hard quartzite is hard work, but it is what it is, so I'm left just wondering if artwork chipped/carved into hard rock surfaces is more common than my feeble mind assumes?
As to the water-worn appearances, that's a good one also. The "Friends of the Pleistocene" seems to be a rich source of field trip guidebook and map information. With all ephemeral features, how they came to be can be fascinating research and field work. What little I've read refers to mapped Owens Lake shorelines varying over many tens of meters during highstands, and we might expect there to have to have been reasonably long highstands within a narrow elevation range for lakeshore wave action to have rounded some hard quartzite outcrops. Two other processes may have contributed--high energy fluvial flow from melting alpine glaciers and grinding action at the interface of glaciers and the quartzite outcrop itself. The picture of the "pavement" outcrop looks almost polished by either high energy flow bringing along lots of hard, coarse sand, gravel, and cobbles, or from simple glacial movement of other parts of the same quartzite horizon grinding along the surface along an alpine glacier's pathway into the Owens Lake. There are some well-identified moraines in the present day lakebed of Owens Lake, so depending on just where the quartzite outcrops are today, relative to the mouths of canyons which may have had alpine glaciers, the rounded surfaces and pavements on hard quartzite might be explained by either active glacial erosion of outwash flows from alpine glaciers above.
Foy
