"Geology, NY Parks Dept"(PDF). Office of Parks, Recreation, and Historic Preservation. Archived from the original(PDF) on December 30, 2019. Retrieved May 30, 2018.
"Geology, NY Parks Dept"(PDF). Office of Parks, Recreation, and Historic Preservation. Archived from the original(PDF) on December 30, 2019. Retrieved May 30, 2018.