Climate Change and Geologic Time
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Name the eons in order from oldest to recent.
Precambrian Phanerozoic
How many eras are there?
3
When do all the eras take place?
During the Phanerozoic eon
How do we divide the eras?
Depends on type of fossil life found in the rock layers
What does Cenozoic mean and what kinds of animals are found during that era?
“New life” -mammals, birds
What does Mesozoic mean and what kinds of animals are found during that era?
“Middle life” -dinosaur
What does Paleozoic mean and what kinds of animals are found during that era?
“Old life” -fish, insects, amphibians, early reptiles
Name the eras from oldest to most recent.
Paleozoic Mesozoic Cenozoic
How many periods are there?
12
What is original horizontality?
When sediments are deposited it happens in horizontal layers
What is superposition?
Oldest layers on bottom, newest layer on top
What is cross-cutting?
Any feature (fault, dyke, etc) that cuts across a layer is younger than the layer
What is inclusion?
Rocks or rock fragments in a layer are older than the layer -any fossil in a layer is the same age as the layer
How many Eons are there?
2
Name the periods from oldest to youngest.
Cambrian Ordovician Silurian Devonian Mississippian Pennsylvanian Permian Triassic Jurassic Cretaceous Tertiary Quatenary
What is an index fossil?
A fossil that is: • widespread • only present for a short amount of time (single layer)
What is an unconformity?
A gap in rock layers
How do unconformities show up?
Shows up as a wavy line in the rock layer
What is an angular unconformity?
• original layers are tilted and lifted • then exposed to erosion • sink back down and new layers are added
What is disconformity?
Layers remain horizontal above and below unconformity All layers are sedimentary
What is non-conformity?
Layers above are horizontal Below the unconformity is bed rock (igneous or metamorphic)
What is absolute (Radiometric) dating?
Method to determine the actual age, in years,of a rock or other object
What occurs in the production of an alpha particle?
Consists of 2 protons and 2 neutrons
What occurs in the production of a beta particle?
A neutron breaks down into a proton and an electron The atom keeps the proton, but loses the electron as a beta particle