Geology and Geomorphology

Most of the Arabian Peninsula is a desert, exceptions at a small scale being oases, and on a larger scale the highlands of Yemen and the southern flanks of the Hadhramaut that are influenced by the southwest monsoon (see section 2.2.2.3 for details of the monsoon). Although it is the limiting effects of an impoverished water supply that creates a desert, the Arabian Peninsula was not always arid; past climates have played a fundamental role in the formation of the landscape which we see today. The processes of weathering and erosion have shaped the geomorphology of the Peninsula and, along with the influence of the vegetation, these processes have produced the soils. The nature of these soils varies with rock type, and rock type depends on a variety of geological factors that include the environment of deposition, the effects of changes in climate through time and other geological processes. Since the underlying terrain has a major influence on soil formation and hence plant community composition, an understanding of the history and geographic distribution of rock and geomorphological types leads to a better understanding of the distribution of vegetation.