Obscure Ceremonial Features in woods north of Thomas Landers Rd, Falmouth

Following a map of Mavor's looking for a feature with the word "chamber" penciled in. In Manitou they wrote that there were no chambers on the Cape - possibly because of the absence of bedrock. So I was curious. Here it is:I am guessing Mavor meant that this might have functioned as a chamber or as a place from which to view the sky.

Also nearby; here is a rock that was split sideways into a sandwich of three parallel slabs. The middle slab has been offset from the other parts:Rocks have been placed in the opening at the other end.
There is no doubt that these Falmouth woods are full of subtle ceremonial features. It is confusing since many of them seem modern. The "chamber" for example is in an area of much soil disturbance and a sense that there was a lot of boulder quarrying there.