The Saq Sandstone is 600m thick and of Cambro-Ordovician age (?). It is vertically and laterally uniform succession, >90% of which cross-stratified. It is a texturally and mineralogically mature, fine to coarse-grained quartz arenite, with subordinate shale, siltstone, breccia and conglomerate. The Saq Sandstone comprises an upward maturing and fining sequence. It was -largely derived from a craton interior made up of pre-existing and multi-cycle sedimentary rocks. A new formation (The Idwah Formation) overlying the Precambrian-Cambrian basement and older than the Saq Sandstone has been defined. This is a remnant of an earlier extensive cover over the peneplained Precambrian-Cambrian surface. The sandstone was partly or totally deposited in a tide-dominated shallow-shelf marine environment. Six Facies Associations have been recognized: (1) Facies Association A (Bar areas); (2) Facies Association B (Inter-Bar); (3) Facies Association C (Inner-shelf); (4) Facies Association D (Shoreline) and (5) Facies Association E (Scree). The Saq Sandstone was deposited intially during a transgression (Lower and Middle) and then during a regression (Upper) cycle. The regression producing a laterally extensive sheet of beach sandstone. The palaeocurrent pattern throughout Saq Sandstone is unidirectional (NE). This together with the orientation of the beach lamination, suggest that the source lay S to SW of the Saq Basin, although it is difficult to reconstruct a palaeoslope from tidally induced flows. The dominance of a single palaeoflow suggest a strongly asymmetrical tidal system
