I gotta be serious here. I think it is the mixture fill for a sign. Dig a hole, insert the sign post, mix some aggregate and concrete together, and tamp it in. It could have been done in the early part of the 20th century. Maybe it was a speed sign.
I'm not trying to be funny, it was just my first thought upon seeing it.
That's a good point!
It was found about 30 feet between that wall of the mill with the arches and what looked like 3 or 4 small walls to the left (facing the fence from the inside) about 20-30 feet back from the fence...
BUT...it wasn't buried at all?!? It was just sitting on the top of the ground, we had a construction company back in the 60's, 70's, and mid 80's and always buried mix for signs/fence posts about 2-3 feet deep so it is just strange. The inside of this feels like iron and looks like iron.
My father suggested maybe it was a piece of hot iron dropped years ago or a piece of a foundation...
Could a road have once been cut into this area?
For those wondering how we got in, it was a friend who works for the State of NJ DEP and had the key to access the padlock on the gate, I wore sandals (BIG MISTAKE!!!) and had to be extremely careful walking.
One interesting thing I spotted was a pipe of free flowing water, the water was crystal clear and had a steady flow around the rear of the property.
I DO NOT condone trespassing of any kind, my advice to anyone who attempts to access the mill is to bring a decent medical kit just in case you get cut, etc. since it was littered with broken glass from beer bottles, even broken crack pipes, all sorts of nasty stuff. Wear good shoes (preferably boots) and DO NOT stand on or near the arches! I witnessed pieces crumble just walking around them and they could give way at anytime and if you are alone you could be SOL.