On Tuesday, March 20 I returned to the site I dubbed Miantonomi's Cave, bringing along a strong flashlight, a compass, and a metal tape measure. This is a highly simplified plan of the site.
The base rock is in blue, and the square boulder on top is in red. The smaller boulder next to the square one is in green. I worked out the alignments by placing the flashlight in notches and grooves that seemed designed to channel sunlight, and photographing where the light fell.
The bottom edge of the square boulder has a 318 degree alignment.
Placing the flashlight along the edge produced a spot of light on a stone face directly
behind the boulder. This would be the green boulder in the diagram. This face of the boulder slants at about 70 degrees relative to the base, so the light ray in the diagram appears to go under the boulder.
Sitting in the seat in the chamber, I am facing the small opening at 285 degrees. I can see sunlight streaming under the leaning edge of the large boulder, right in front of me. Perhaps this is the site for determining equinox sunsets. I wonder who sat here before me, and how long ago.
August 13 or Green Corn Festival
I noticed that the larger window had a notch in the bottom, presumably to channel the last rays of sunset light. I placed my flashlight in the notch, and photographed the chamber. The bearing was about 305 degrees, corresponding to August 13.