GLY 101LEC Lecture Notes - Lecture 4: Cambrian Explosion, Plate Tectonics, Hadean
26 Sep 2018
School
Department
Course
Professor
Document Summary
All isotopes have their own rate of decay. Sometimes there is an overlap in the sequences of rock types. 4. 6 billion pennies is twice the circumference of the earth. Subdivisions of time-scale is divided up based on either: a characteristic of the time period or a specific place. Roughly 5 major mass extinctions and 3 minor extinctions throughout earth"s history. Single celled life (first life) february 25 (3. 8 ga) First human like ancestors appear at 3 pm december 25. Homo sapiens appear december 31 at 11 pm. Last ice age ends december 31 11:59 pm. Life first appeared on earth ~ 3. 8 ga. Early life consisted of anaerobic single celled organisms (without nuclei) O2 from cyanobacteria built up in atmosphere by 2 ga. Around 542 ma marks the first appearance of hard shells. Life became diverse rapidly in the cambrian explosion. Hadean eon (the oldest eon; starts at 4. 6 ga)
