Print shows the rock formations at Bald Eagle (or Sinking Spring) Valley in Pennsylvania. Illus. in: The Columbian magazine, or, Monthly miscellany. Philadelphia : Printed for Seddon, Spotswood, Cist, and Tren More
Print shows rock formations and cliffs at the Pulpit Rocks on Warrior Ridge in Huntingdon County, Pennsylvania. Illus. from: The geology of Pennsylvania; a government survey by Henry Darwin Rogers, State geolo More