Chapter 8 Science Flashcards
Geologic time
deep time, earth time
numerical/abstract time
amount of time elapsed as determined by analyses of the decay of naturally occurring radioactive elements
relative time
relative order of events, youngest to oldest
geologic time scale
calender of Earth’s history
relative dating
sequence of events through time: establishing order in with rocks deposited and subsequently deformed and altered
principles of geologic time
super position, cross cutting, fossil succession
super position
oldest layers on the bottom, younger layers near the top
cross cutting
anything cutting through layered rocks, younger than everything it cuts
fossil succession
fossils appear in a recognizable order in the rock record.
index fossil
short lived, common, widespread, fossils that lived during specific periods of time.
Continuous deposition
No period of erosion or mom deposition
Unconformity
The result of period of erosion and non deposition =missing time
Numerical
Assigning an actual date to the rock
Parent isotope
Decays to daughter
Radioactive decay
Occurs at a constant logarithmic rate
