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
Normal gravity formula equator and lowest the poles. The formulas for calculating the normal gravity is based on the assumption of an imagined rotationally symmetrical ellipsoid model of the earth, the surface of which is identical to an equipotential surface. Consequently this formula depends only on the geographical latitude and the elevation of geographical location. For the normal gravity formula_1 of the sea level ellipsoid, i.e. elevation h = 0, this formula by Somigliana (1929) applies (after Carlo Somigliana (1860–1955)): with Due to numerical issues, the formula is simplified into this: with For the Geodetic Reference System 1980 (GRS 80) the parameters are