ERS111H5S Lecture Notes - Lecture 4: Snowball Earth, Neoproterozoic, Hadean

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20 Oct 2018
How we use microfossils
A time period where you know the fossil had to exist in
Geological time: time since earth was formed
Key times we need to know are in red
Hadean: earth just forming, molton
Archean: first evidence of life
Proterozoic: complex life, multicellular organisms
Phanerozoic: living in right now, rise of extremely complex life
Moon forming
Oceans forming
Soft bodied organisms
Complex life
Neoproterozoic: snowball earth
Paleozoic: age of fish
Mesozoic: age of dinosaurs
Cenozoic: age of mammals, dominant land based organisms
Ones in red are the only ones we need to know
Use of radioactive particles and their decay
How much of the isotope should be in the rock vs how much is actually in the rock
15 different forms of carbon
13 - stable, if it were to form it is stable and wont change
12 - also stable
14 - rare, but able to be detected
Carbon 14 starts to decay and switches to a daughter isotope, stable
Number of daughter isotopes increases
Since we know rate of decay, we can know half lives
Relative: stenos principles, index fossils
Fault plane: fracture in the rock
Solids only
Happen close to earth surfaces
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