Turtle Cairn - Spruceton NY

Robert Buchanan writes:

Attached is a picture of a turtle cairn taken on the Sunday field trip to the Spruceton site. The site has many well constructed cairns including 3 turtle cairns.

The eye of the pictured cairn was formed by a notch (or cavity) left by a stone that had fallen or been removed from the conglomerate head stone. This cavity collects rainwater and so forms a wet mark around the eye that can be seen in the image.

Update: Norman Muller sends this photo from Killingsworth:
Hard not to agree that these two examples are very similar.