Abstract
The area between Msus and Soluq (428 km2) proved to be enriched with large-scale karst features, mostly dolines, but the small scale features such as Karren and solution cavities are less common or absent. Representative dolines have been analyzed from selected sub-areas, individually, to understand their geometry, nature and development mechanisms. A total of sixty dolines are documented herein; fifteen of them are classified as doline-like shallow depressions (i.e. diameter ranges from 125 to 350m and depth from 5 to 25m) and the other “forty-five” are collapsed dolines (i.e. diameter ranges from 75 to 250m and depth from 25 to 60m). The development of doline-like shallow depressions, is linked to the stream pattern, strictly, the tributary catchment area, meanwhile, the deeper ones are tectonically controlled, almost at fault intersections. Additionally, the lithological homogeneity “i.e. miliolid-peloidal grainstone” is another, important contributor to their development. The study area is characterized by high density in fractures (faults and joints), with a major northwest trend, identical to that of the Wadis trend, however, the minor northeast trend is more or less parallel to the tributaries. Accordingly, dolines are controlled by these two trends. The spatial distribution of the documented dolines is controlled by two barriers, the upper escarpment (N-S direction) of Al Jabal al Akhdar and the major NE-SW fault line, located at the southeastern part of the area of concern. Obviously, to the southeast of the NE-SW fault line barrier, relatively, less developed karsts (i.e. dolines become fewer, shallower, and larger with irregular shapes) are documented.