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Quaternary lakebed deposits have been recorded in different parts across Arabia, which are now drained by the eastward flowing drainage networks from Al Sarawat Mountains. The analyses of digital elevation model (DEM), satellite images, and geological maps show that the lakebed deposits are mainly contained within a great arch depression occupying the trough between Al Sarawat Mountains in the west and the escarpment of Tuwaiq in the east and Hadarmawt plateau in Yemen from the south to Wadi Sirhan depression near the Syrian-Jordanian border in the north. The basins within this mega-depression have been interconnected by tributary flows which was consequent in the northward direction. The conspicuous ridge of Tuwaiq, which extends northward for about 800 km and rises for approximately 200 m above its western floor, has been breached by numerous subsequent deep incised canyons and funnel-shaped cuts carved at different elevations. The formation of several wadi canyons and funnel cuts along the entire extent of Tuwaiq clearly suggests that the breaching of this conspicuous escarpment was sudden and rapid, as the northern outlet of this mega-lake was insufficient to discharge the water. The overflow arms have developed extensive alluvial fans on the Arabian coast; the fan of Wadi Al Batin covered approximately 60,000 km(2) in South Iraq, Kuwait, and northeastern parts of Saudi Arabia. The age dating of the Quaternary deposits in different localities suggests the occurrence of this event between 13,000 and 8,500 years before present; however, the discrepancies could be related to technical issues or the scouring of older bed deposits and its entrainment in the younger deposits of this great flood.