Peak District or The Peak, dissected plateau, c.30 mi (50 km) long and 22 mi (35 km) wide, Derbyshire, central England, forming the southern extremity of the Pennines. Kinderscout (2,088 ft/636 m) is the highest peak. Dovedale and Wyedale are the region's major valleys. Peak District has many caves including Peak Cavern and Speedwell. Peak District National Park (c.500 sq mi/1,295 sq km) was established in 1951.