Past sea level has varied by somewhat more than a hundred metres. This is primarily due to the growth and decay of ice sheets (mostly in the northern hemisphere) with water evaporated from the sea. The Mediterranean Basin's gradual growth as the Neotethys basin, begun in the Jurassic, did not suddenly affect ocean levels. While the Mediterranean was forming during the past 100 million years, the average ocean level was generally 200 metres above current levels. However, the largest known example of marine flooding was when the Atlantic breached the Strait of Gibraltar at the end of the Messinian Salinity Crisis about 5.2
Eustatic sea level ocean water mass (ice sheet runoff) • When an ice sheet such as Greenland begins to lose its ice mass due to melt, the liquid water is transported to the ocean. According to the ‘bathtub theory’, ice sheet runoff from Greenland will effect Eustatic sea level in all areas of the world whether proximal or distant. • Ocean water mass may also shrink in size if continental ice sheet grow in size, thereby removing liquid water from oceans and converting them to grow ice sheets 2. Changes in the size of the ocean basin (GIA: glacial isostatic adjustment) • The