SummaryDistinctive channel patterns in the floors of alluvial clay depressions in Iraq and Sudan as well as in other parts of the arid zone have been described as gilgai in the past though their morphology differs from examples of gilgai as originally described in Australia. The soils on which the channels develop vary considerably and do not always contain large proportions of expanding lattice clay. The formation of the micro‐relief may not necessarily involve heaving of the subsoil as in the Australian gilgai. It is formed rather by a process of uneven settling and compaction, the patterns of channelling being controlled by pre‐existing surface irregularities. If the formation of the micro‐relief does not involve heaving, it is probable that the channels will not reform after reclamation. The term‘tabra channels’ is suggested for th