As I mentioned in a previous post, some of the boulders at Miantonomi's Cave have round pits that look man-made. Here are the prominent ones on the top face of the square boulder.
I was wondering if sticks placed in the holes could have been used as sights for astronomical observations. Unfortunately, the bearings along the lined-up holes don't correspond to any events. Maybe the holes were created by native techniques when the boulder was squared off. Here is a small slab with two of these holes, about 10 inches apart, resting on the ground directly west of the structure. Presumably this was left over from the process. I once heard or read somewhere that very old gravestones in a Narragansett cemetery had two holes. Maybe the gravestones were produced by this type of stone work.
A boulder on the east side of the structure has a large carving of a triangle. The base is 19 inches wide. The lines are about 2 inches deep, so carving this required a lot of time and energy. Perhaps the triangle symbolizes a sacred space.
I have seen large triangles in other sites, such as the structure in the 9/3/11 post, which has a huge manitou standing behind it. On the west side of the structure's base is this odd shape, which from this angle looks like an arrowhead pointing up inside a recessed square area.
The edges of the surrounding square shape look like it was gouged out of the rock. From this angle, the center form looks like a carving of a bird. Some genius spray-painted the square black a long time ago.
Here is the structure from the west, with the mark to the right. It probably was carefully built as an observatory, and had great spiritual significance. Maybe someone remembers.