GEOMORPHOLOGICAL FEATURES AND SEDIMENTOLOGICAL ASPECTS OF SOME COASTAL AND INLAND SAND DUNES, JEDDAH REGION, SAUDI-ARABIA

The study reported in this paper illustrates the geomorphologic featur es and the sedimentological characteristics of coastal and inland sand dunes in the Shuayba coast, the southern Corniche of Jeddah, and alon g Jeddah and Makkah highway. The geomorphologic Features are studied o n basis of dune type, modification, wind ripples, and internal structu res. Differentiation between coastal and inland dune sands has been ba sed on grain-size parameters, cumulative curves, bivariat plots and mi neralogy. Inland dune sands are Finer, and better sorted with single s altation populations as compared to coastal dune sands. The heavy mine ral suites of both sand dune types display a dominance of less stable minerals (e.g. amphiboles and pyroxenes) over the stable ones (e.g. zi rcon, tourmaline and rutile). It is concluded that the local topograph y and sand-carrying winds affect the distribution and morphology of th e inland sand dunes along Jeddah and Makkah highway.