In 1891, George F. Becker told the American Geological Society that in the spring of 1869, Clarence King, director of the Survey of the Fortieth Parallel, and a respected geologist, was conducting research at Tuolumne Table Mountain.  Becker stated: "At one point, 
close to the high bluff of basalt capping, a recent wash had swept away all talus and exposed the underlying compact, hard, auriferous gravel beds, which were beyond all question in place.  In examining the exposure for fossils, he [King] observed the fractured end of what appeared to be a cylindrical mass of stone.  The mass he forced out of its place with considerable difficulty on account of the hardness of the gravel in which it 
was tightly wedged.  It left behind a perfect cast of itself in the matrix and proved to be part of a polished stone implement, no doubt a pestle."

Becker added: "Mr. King is perfectly sure this implement was in place and that it formed an original part of the gravels in which he found it.  It is difficult to imagine a more satisfactory evidence than this of the occurrence of implements in the auriferous, pre-glacial, sub-basaltic gravels." 

From this description and the modern geological dating of the Table Mountain strata, 
it is apparent that the object was over 9 million years old.