Relative Dating
The method of dating rocks compared to the rocks around them
What is Relative Dating
The unstable elements found in rocks/fossils
What is a radioactive isotope?
When sediments go under compacting and cementing processes they become
What are sedimentary rocks.
The largest division of time on the Geologic Time Scale
What is an Eon?
How long ago did dinosaurs go extinct?
Approximately 65 million years
What is the Law of Superposition?
Younger rocks on top, older rocks on the bottom
Isotopes are identified by their varying number of...
What are neutrons?
When igneous, metamorphic and sedimentary rocks go under weathering and eroding they become
What is sediment
The smallest division of time on the Geologic Time scale
What is a period?
How many mass extinction events has Earth experienced?
5
Samples of layered rock in an area
What is a Stratigraphic Column?
Process that occurs when the parent isotope decays into a new atom
What is radioactive decay?
When ANY rocks go under melting they turn into
what is magma
What are the 3 divisions of time on the Geologic Time Scale?
Eon, Era, Period
How can you differentiate between extrusive and intrusive igneous rocks?
extrusive- glassy, gas bubbles, small crystals
Intrusive- large crystals
True or False: Fossils can be found in any rock layer
False: Only sedimentary rock layers
The time it takes for half the atoms in a sample to change from a radioactive isotope to a new stable atom
What is a half life?
This type of igneous rock can have holes due to gas bubbles getting trapped when the lava cools
What is extrusive?
Name one period on the Geologic Time Scale
Triassic, Jurassic, Cretaceous, Cambrian, Quaternary, Tertiary, etc.
Name any rock layer found at the Grand Canyon
Bright Angel shale, Hermit shale, Kaibab limestone, etc.
The process in which geologists analyze stratigraphic columns to find areas with common rock layers and fossil. Can be used to match rock layers across large distances
What is correlation?
A radioactive isotope under goes a half life every 22 years. How much of the original isotope would remain in a 20 gram sample after 66 years?
2.5 grams. (3 half lives, 1st:10, 2nd:5, 3rd:2.5)
Name all the processes IN ORDER to turn magma into sediment and then into a metamorphic rock
cooling & crystallization into igneous, then weathering and erosion into sediment, cementation and compaction into sedimentary rocks, then heat and pressure to become metamorphic
The largest Eon on the Geologic Time scale
Phanerozoic
Put the three periods of the Mesozoic Era in order from oldest to most recent
Triassic, Jurassic, Cretaceous