Cuesta Region of the Tuwayq Mountains

Abstract

By the cuesta region of the Tuwayq Mountains is meant the area where the landscape is controlled by asymmetric ridges with one face (dip slope, cuesta back slope) long and gentle, conforming with the dip of the resistant Mesozoic beds, rarely exceeding 1°, and the opposite face (scarp slope, escarpment) steep and clifflike, formed by the outcrop of these resistant rocks, mostly limestones. It is a vast area occurring in a great curved belt parallel to the eastern margin of the Arabian Shield. In this belt relatively low hills protrude above flat plains. The gentle slopes of these hills conform with the dip of the beds, and the steep slopes descend abruptly from their crests, forming steep escarpments facing west and capped by resistant limestones. The west-facing scarps offer excellent opportunity for studying the rock sequences; some of the rock units can thus be traced over hundreds of kilometers. The softer formations between cuestas consist mostly of sandstones and shales which are less resistant against erosion and denudation. They occur in the intervening valleys and plains, but although they are often only partially masked by gravels and sands, these units are fairly well known. The cuesta region of the Tuwayq Mountains constitutes one of the most spectacular features of the central Arabian landscape.