Natural. There are a lot of undiscovered pictographs, petroglyphs, and true mysteries out there. A lot better usage of time searching for the real thing.
slick!.. I have communicated with Kevin at portable rock art and he recognized some of the microlithic art profiles i I sent him.. the gravel has been worked there .. campsite for oh ... 15,000 years.. i understand now how they documented 2.6 million artifacts at the gault site near ft hood.. they eventually just had to close shop...every inch of this .. gigantic mound maybe.. has artifacts from pea gravel to boulders.. even the stone ledges have been worked..local buisnesses are aware.. UT thinks it was a work factory of sorts.. think I have Dino related finds.. its boggling but I got my facts staight folks