Last weekend I spent a delightful late afternoon at Miantonomi's Cave. It was a beautiful day to sit outside and enjoy the serenity of the place. Here is the view looking west.
This structure was probably not surrounded by trees hundreds of years ago, when it was used as an observatory. Today the light patterns may be diffused by the trees. When I arrived at 5:35, the cave was in darkness because the boulder on top of the structure was blocking light from the windows. The large window is visible to the far left.
However, I did not have long to wait, since by 6:04, light was entering the cave through the large window and forming a large triangle on the wall. The light also formed a narrow streak where there is a notch in the large window. This is the same notch that formed a prominent light streak on August 13.
As the light spread across the wall, it revealed two prominent marks in the wall, a shallow depression with a light, curved mark, and a large gouge. The picture above was taken at 6:12. Here they are highlighted in a photo taken at 6:10 PM.
Finally, the light formed a sharp point at 6:17, and slowly vanished. In the lower photo, the edge of the projecting stone is seen to the right.
The cave was dark at 6:20 PM, sunset. The whole progression of light in the cave only took about 30 minutes. The marks on the wall that the light traveled across are interesting. The shallow curved one reminds me of Kokopelli, the fertility god from the southwest. This would certainly be appropriate for vernal equinox. This mark seems deliberate, and it feels scratched-in. Here is a close-up.
I can't wait to see what winter solstice will reveal.