Discussion on ‘Hydrogeology of the Umm Er Radhuma aquifer, Saudi Arabia, with reference to fossil gradients’ by W. Bakiewicz, D. Milne & M. Noori

Abstract

Dr J. C. Doornkamp writes: The synthesis provided by Bakeiwicz et al . has to be admired for its scope and enormous regional extent. The difficulty with such analyses is that sometimes the details do not fit. This is the case for Bahrain, as shown in their figs 3 and 4. The interpretation given to the interior basin of Bahrain as a portion of a ‘solution collapse feature’ cannot be supported by evidence on the ground. This interior basin is not just one but 10 discrete draining basins partly eroded by water and partly excavated by wind. The net effect is to produce an eroded anticline. In their fig. 4 Bakiewicz et al . identify palaeo-river courses on the southern portion of Bahrain: these do not exist. What appears to have happened is that the long dark trails of flints associated with outcops of the West Rifa Flint Formation (part of the Damman Formation of Bakiewicz et al .), as concentrated by synclinal folds, have been mistaken for river gravels. This misinterpretation could happen, of course, if only air photo interpretation was available to the authors. Both of these points can be followed up more fully by reference to Doornkamp et al . (1980). The authors wish to thank Dr Doornkamp for his useful comments. Without going into details of Bahrain geomorphology, which is outside the scope of the paper, there is no doubt that a solution collapse feature, associated with the evaporites of the Rus Formation, does exist on Bahrain. This