GEOG 272 Lecture Notes - Lecture 14: Volcanism, Northern Hemisphere, Regelation

• School: McGill University
• Department: Geography
• Course: GEOG 272
• Professor: Wayne H Pollard

Document Summary

Based on terrestrial deposits it was originally thought that there were 4 pleistocene glaciations separated by interglacial. By comparison the marine sediment record is much more complete and continuous. As a result, the analysis of fossils and oxygen isotopes have yielded a much more complex picture of 100+ isotope stages over the past 2. 6 ma and 20+ cycles of glacial advance. Its only when it melts does it go back to the system: this is how we are able to correlate. This is a world map where various events were pointed out last class: we have the opening of the drake passage = south america used to touch. It i(cid:374)(cid:272)(cid:396)eases the al(cid:271)edo, p(cid:396)e(cid:448)e(cid:374)ts the ea(cid:396)th"s (cid:396)adiatio(cid:374) f(cid:396)o(cid:373) being absorbed: this also helps to cool down temperature, this is usually enough to trigger periods of glaciation. The antarctic ice started to from 32 million years ago. The northern ice sheet (greenland) started from just under 10 million years ago.