sentences:  The Catawba forms the eastern border of the county and much of the central part of the county is in the drainage basin of its right tributary, the South Fork Catawba River.The county is located in the Piedmont region of central North Carolina, which consists of gently rolling terrain frequently broken by hills, river and creek valleys, and low, isolated mountain ridges.The highest point in Gaston County is King's Pinnacle, a rocky monadnock which sharply rises over above the city of Gastonia.