Have we seen this (h/t Tim MacSweeney)?
I paricularly like this quote:
"...It is clear to all reasearchers of piled rock features that the variety of features encountered reflects differing aspects of functional and cultural affiliation. No one questions that some are pre-historic and some are historic, or that some are mortuary and others are simple discard piles. The problem is sorting out the types..."
Wait! It gets better:
"...One startling discovery was the recovery a small "superball" about 40cm below the top of rock pile 4. This obviously modern artifact illustrates how quickly an artifact can work its way through a rock pile...."