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
Singapore-Cambridge GCE Normal Level "(abbreviated as N(A))" and Normal (Technical) "(abbreviated as N(T))" streams respectively. The GCE N(A)Level-Normal Academic Level, is taken by Normal Academic students after four years of secondary school education. This may lead to a possibility of moving on to the Secondary 5N(A)stream to take their 'O'-Levels. Alternatively, they may take the O-Levels without taking the N(A)-Level.In the Normal (Academic) course, students offer 6-8 subjects in the GCE ‘N’ Level examination. They have, as compulsory subjects, English Language, Mother Tongue and Mathematics. For upper secondary, Combined Humanities and a Science subject are also compulsory. The aggregate used for this stream is