Mountains in Juniata County include Tuscarora Mountain and Shade Mountain. Agricultural land and forested land make up most of the county's area. Major rivers and creeks in the county include the Susquehanna River, the Juniata River, Tuscarora Creek, and West Branch Mahantango Creek. It borders seven other counties. The county lies over 16 different rock formations (which are from the Ordovician, Silurian, and Devonian) and 51 different soils.