Flashcards in Geologic time Deck (18):
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
Age of base of Phanerozoic
End Paleozoic date
End Mesozoic Date
Faunal Succession and 5 Major Mass Extinctions during the Phanerozoic Eon
Late Devonian Crisis
Permo-Triassic Extinction (“The Great Dying”)
End-Cretaceous Extinction - huge asteroid hits earth.
Phanerozoic Eon: Three Evolutionary Faunas of Marine Animals (Cambrian, Paleozoic, & “Modern”)
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.
Clair Patterson (Age of the Earth – why did he have to use meteorites?)
He made two correct assumptions- that the meteorites were leftover materials from the beginning of the solar system and that they would maintain an unchanged internal chemistry.
Igneous Rocks = zircons
zircons are like time capsules in rocks. they help measure the age.