Across the “river” from the petroglyphs are a few mortar holes where the Native Americans who lived here ground seeds into a powder for cooking. There are five holes.
The largest is a foot deep and most likely a heavy thick stick was used and the person stood up pounding the stick up and down. That is the toe of my boot to give you a size reference.
I could picture the women sitting here chatting away while the river slowly flowed by, not a bad scene at all. Meanwhile the men folk were on the other side doing important men work like making pictures on rock. That is a picture frame I found nearby in case you are wondering.
No water flows in the river these days except only after a brief rain storm.