Geologic time Flashcards
3 Eons
Archean, protozoic, Phanerozoic
3 eras in the Phanerozoic
Paleozoic, Mesozoic, Cenozoic
12 Periods in order
Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic, Cretaceous, Paleogene, Neogene, Quaternary
Age of the earth
4.55 Ga
Age of base of Phanerozoic
541 Ma
End Paleozoic date
252 Ma
End Mesozoic Date
66 Ma
Faunal Succession and 5 Major Mass Extinctions during the Phanerozoic Eon
End-Ordovician
Late Devonian Crisis
Permo-Triassic Extinction (“The Great Dying”)
End-Triassic Extinction
End-Cretaceous Extinction - huge asteroid hits earth.
Phanerozoic Eon: Three Evolutionary Faunas of Marine Animals (Cambrian, Paleozoic, & “Modern”)
Trilobites
Inarticulate brachiopods
Archaic mollusks and primitive crinoids
Establishing age relationships of sedimentary rocks
using radiometric dating of zircons and crosscutting relationships
what is an isotope?
An element which contains a different number of neutrons.
What is radioactive decay?
When a neutron releases an electron and becomes a proton.
What is a half-life?
The amount of time in which half of the parent isotopes to decay into daughter isotopes
Parent-Daughter isotope ratios
The parent isotope is the original isotope, and the daughter isotope is the isotope which the parent isotope decays into.
Tells us, along with the half life, what the age of the rock is
How do geologists figure out the numeric age of a rock? (What do they need to know to do this?)
The parent-daughter isotope ratios and the half life.
