Dear calo;
I have a suspicious hunch that those carvings may in fact be cattle brands. The best way to confirm this would be to do a bit of research at the local county courthouse and confirm or deny these suspiciouns, my friend.
Those markings look to be old and they do not seem to be mindless graffitti, rather they are simple symbols, easy to produce into branding irons at any local blacksmith shop. The barred cross was a hugely popular brand, owing to it's origins as the Royal brand of Spain during Colonial times, as is the stylized numeral 5. There are other interesting symbols on that rock which would are about the correct size and shape to be cattle brands, therefore it might behoove you to spend a day going through the county records where the rock is residing.
If nothing else, you will walk away with a better understanding of the people who lived in that county.
Your friend;
LAMAR
