EOSC 112 Lecture Notes - Lecture 6: Pleistocene, Tibetan Plateau, Cambrian Explosion
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Yet, there is evidence of extreme ice ages and extreme tropical ages with no ice. The geological time is divided into intervals at different levels. The oldest are stromatolites (layered minerals deposited by ancient colonies of cyanobacteria: during the phanerozoic = complex organisms producing hard skeletons which leave fossils, this fossil record is what gives us information about this era. Eons are subdivided into eras: phanerozoic = paleozoi(cid:272) (cid:894)(cid:862)old life(cid:863)(cid:895), mesozoi(cid:272) (cid:894)(cid:862)(cid:373)iddle life(cid:863)(cid:895) a(cid:374)d ce(cid:374)ozoi(cid:272) (cid:894)(cid:862)(cid:374)e(cid:449) life(cid:863) Eras are then divided into periods cenozoic (0-65 million years) tertiary (65-1. 8 million years) and quaternary (last 1. 8 million years) Climate: the climate is characterized by long periods of warm climate separated by shorter episodes of cold climate. Generally, it was warmer during the first 2 billion years, then somewhere between 2. 5 and 2. 3 billion years ago there was evidence of the first glaciation, the huronian glaciation.
