I have been trying my hand at finding old habitations, etc., on public land near me in Somerset County. While trying to locate an 1860 farmstead I came across a circular depression about 20 feet across and 5-6 deep with sloping sides of something like 45 degrees. The area has a history of logging and farming, and peach orchards. I'm thinking it might be an old cesspool that gradually eroded inwards? The area is extremely rocky, and it would not have been easy to dig that out. Also, it doesn't seem to be the cavity left by an uprooted tree - there's no large tree lying near it. Any ideas?