Jabal Tuwaiq or Tuwaiq Escarpment is a narrow escarpment that cuts through the plateau of Najd in central Arabia, running approximately 800 km from the southern border of Al-Qasim in the north, to the northern edge of the Rub' al Khali desert near Wadi ad-Dawasir in the south. It is 600 m (2,000 ft) high and also has a Middle Jurassic stratigraphic section. The eastern side slopes downwards gradually, while the western side ends in an abrupt manner. The escarpment can be thought of as a narrow plateau, though the locals refer to it as a jebel ("mountain"). Marshall Cavendish used the name "Tuwayr Mountains" to describe mountains of central Arabia, distinct from the Shammar in the north, the Dhofar in the south, and the Hajar to the east.