ENVS 2160 Lecture 27: Week 9 Notes - Cenozoic&Quaternary Glaciations
22 Jun 2016
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Document Summary
Cooling starts in the tertiary (fig 13. 1: evidence from: Record decreasing deepwater temperatures and increasing glacier cover through the tertiary. During the eocene, earth was relatively warm tropical climates in britain, northern france and central. Usa and temperate climates in polar regions (fig 13. 1: oceans ~18c. Cooling in late eocene corresponds to development of the antarctic circumpolar current (~50ma) as. By late eocene-early oligocene, sizable glaciers existed in eastern antarctica and may have triggered a sea level drop as indicated by diamictites. Rapid and extensive cooling in lower oligocene: marine sites have thicken accumulations of ice-rafted debris, oxygen isotope measurements indicate ice volumes ~1/2 those of the present day. Slight warming of surface water temperatures ~20-12ma (middle miocene) followed by a 2nd major cooling. Climatic amelioration occurred around 5ma (at start of pliocene) trees in iceland, greenland and canada as far north as 82 degrees.
