Cone Karst in El-Galala El-Qibliya Plateau, Eastern Desert, Egypt

Satellite images and field investigation demonstrated that El-Galala El-Qibliya Plateau (Southern Galala) contains residual hills. They are located in separate localities and have not been previously described in the plateau. The residual hills are developed in Eocene limestone rocks. The residual hills are dissected by dry valley (wadi) and occasionally plains. The residual hills resemble karst hills, and their origin requires humid climate conditions, which are different from the current hyper-arid climate conditions of the plateau. One sampling area was selected for field survey and to identify some evidence of their formation. Through a detailed field survey on 120 slope profiles on 30 hills with 515 slope segments on 24 hills of the 30 hills and analysis of slope forms, it was found that the residual hills are cone valley karst hills and fenglin basin hills at a few localities. They have two types of hills: Sewu and Tual. The residual hills are conical to elongated. Most of the hills are aligned roughly along the north direction, controlled by faults and joints. The height of the hills is less than 15 meters. Their diameters range from 7 m to 70 m. Their diameter/height ratios range from3.57  to 8.71, with a significant positive correlation between their diameter and height. Most of the slope angle of the hills ranges from 10° to 30°. The hills have more than one slope curvature, with a high percentage of convex slope at the upper part of the hills. Some of the hills have small vertical cliffs and staircases. Karren features, dissolution caves, and likely base-leveled corrosion plain are associated with the hills. The residual hills formed likely since Oligocene. A hypothetical genetic model is introduced reflecting their evolution as a result of a combination of karstification and tectonic movement, geologic fractures, paleoclimate, and changes of base level.