The nature of the strata points strongly to several cycles of the Mediterranean Sea completely drying and being refilled (Gargani and Rigollet, 2007), with drying periods correlating to periods of cooler global temperatures; which were therefore drier in the Mediterranean region. Each refilling was presumably caused by a seawater inlet opening, either tectonically, or by a river flowing eastwards below sea level into the "Mediterranean Sink" cutting its valley head back west until it let the sea in, similarly to a river capture. The last refilling was at the Miocene/Pliocene boundary, when the Strait of Gibraltar broke wide open permanently. Upon closely examining the Hole 124 core, Kenneth J. Hsu found that:  Research since then has suggested that the desiccation-flooding cycle may have repeated several times during the last 630,000 years of the Miocene epoch. This could explain the large amount of salt deposited. Recent studies, however, show that the repeated desiccation and flooding is unlikely from a geodynamic point of view. Some major questions remain concerning the beginning of the crisis in the central Mediterranean Basin. The geometric physical link between the evaporitic series identified in marginal basins accessible for field studies, such as the Tabernas basin and Sorbas basin, and the evaporitic series of the central basins has never been made. Using the concept of deposition in both shallow and deep basins during the Messinian (i.e. assuming that both Basin types existed during this period), two major groupings are evident: one that favours a synchronous deposition (image c) of the first evaporites in all the basins before the major phase of erosion (Krijgsman et al., 1999); and the other that favours a diachronous deposition (image a) of the evaporites through more than one phases of desiccation which would first have affected the marginal basins and later the central basins. Another school suggests that desiccation was synchronous, but occurred mainly in shallower basins. This model would suggest that the sea level of the whole Mediterranean basin fell at once, but only shallower basins dried out enough to deposit salt beds. See image b. As highlighted in the work of van Dijk (1992)  and van Dijk et al. (1998) the history of desiccation and erosion was complexly interacting with tectonic uplift and subsidence events, and erosional episodes. They also questioned again like some previous authors had done, whether the basins now observed as "deep" were actually also deep during the Messinian Episode and gave different names to the end-member scenarios described above.