This awkward terminology to designate the two strata results from the fact that the strata as designated by the original excavators in the 1930s have since been clarified. The original excavators divided stratum IV into two phases, IVa and IVb the latter being earlier. Subsequent excavation and analysis have shown that strata Va and IVb should be combined into one stratum. As is customary, the excavators number the strata from the top down.