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
Centigrade 232 another Centigrade 232 poem ("Ode To A Crystal Set") appear on the CD's opening track "Second Degree Soul Sparks". In October 2007, Voiceprint Records re-issued "Centigrade 232" in a package containing both a reprint of the 1977 book and a CD of the 1986 recitations. Voiceprint Records label head Rob Ayling passed a copy of the cassette tape of Calvert's recitations to Dave Brock and asked him to set some of the titles to music. The music was played by the then current line-up of Hawkwind, but some titles were lost at the mixing stage delaying the release until August