The Trail Guide pdf says, "(125) Marble Caves: This marble was originally a large coral reef that surrounded a volcanic island in an ancient ocean. During the formation of Pangea, the ocean was subducted under Proto-North America. The coral reef was compressed, heated, and metamorphosized into the marble rocks you now see. Notice how the rain water seems to have melted and washed away the marble due to our slightly acidic rain. Now take a look at the dark rock that was deposited on top of the marble. This rock, called hornblende schist, was originally laid down during a series of volcanic eruptions that coated the coral reef with multiple layers of volcanic ash."
Peter Marteka writes:
“It was only years later that I learned that for a real cave, you need the presence of limestone or marble. The only publicly accessible caves in Connecticut are "Tory's Cave" in New Milford and "Squaw Cave" in Bolton, where an Indian maiden and her Dutch sailor lover hid from colonists...But after a recent visit to Little Laurel Lime Park in Seymour, I'm thinking of adding its caves to the short list.
To reach the caves, visitors should stay on the main trail, following it to the left each time they encounter a secondary trail. After reaching a beautiful stone wall high on a ridge, visitors can turn left or right to see the caves, which are absolutely fascinating, with stratified layers of hardened rock on top of the layers of marble. It's a strange sight to see the huge trees growing out of the sides of the ledges next to the caves.”