Is this location in an old mining area? It's a typical mound of stones used to denote a claim corner ca 1860-1960, more or less. Were any of the larger rocks set into the ground (buried half-way)? If so, the claim may date to 1860-1920, more or less, and there may be letters and/or numbers carved into them. If there are, they will be heavily weathered and hard/impossible to read, depending on the type of rock. Shining a light or the sun's reflection with a mirror at a very low angle across the rock's surface often helps make out the carvings, if there are any.
