Mount Tremper, officially known as Tremper Mountain and originally called Timothyberg, is one of the Catskill Mountains in the U.S. state of New York. It is located near the hamlet of Phoenicia, in the valley of Esopus Creek.At 2,740 feet (840 m) in elevation, it is well below the higher peaks of the region. Its slopes were a source of two major local products during the 19th century: hemlock bark, a source of tannin, and bluestone used in construction.