Several possible causes of the series of Messinian crises have been considered. While there is disagreement on all fronts, the most general consensus seems to agree that climate had a role in forcing the periodic filling and emptying of the basins, and that tectonic factors must have played a part in controlling the height of the sills restricting flow between the Atlantic and Mediterranean (Gargani and Rigollet, 2007). The magnitude and extent of these effects, however, is widely open to interpretation (see, e.g., van Dijk et al. (1998).