BIOL 1510 Lecture Notes - Gondwana, Atmospheric Circulation, Evolutionary Radiation
Document Summary
In a vertical sequence of sedimentary or volcanic rocks, a higher rock unit is younger than a lower one: down = older, up = younger. Rock layers were originally deposited close to horizontal. A structure that is included in another is older than the including structure. Gaps in the rock record: from erosion. Geologic processes that operated in the past were constrained by the same physical laws that operate today. Radioactive parent atoms breakdown to known daughter atoms at known rates. These are not completely accurate for carbon 14- Nitrogen 14 because of the atom bombs that were set up: ex: how old is a fossil that has a 14c/12c ration of ~1/32 of a present day organism. Laurentia: super continent that appeared around the same time as gondwana. First person who thought of this was charles darwin: came up with the idea that older species were extinct. Evolutionary radiation (a bunch of things come from 1 source)
