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68 Cards in this Set

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  • Back
What 2 very important things occured during the Permean period?
1) The supercontinent Pangea formed (created the Appalachian Mts.)
2) Created the greatest mass extinction of organisms on Earth.
Putting rock units in sequence from oldest to youngest and determining an actual age:
Relative age
What is the largest chunk of geologic time?
How old is the Earth?
4.6 billion years
"Old life":
Linking together rock layers across long distances:
Recent epoch:
Which unit of geologic time do we know the least about?
Precambrian b/c there us an abscence of fossil evidence since most of the rocks are igneous/metamorphic and don't contain fossils.
A surface of erosion or nondeposition that represents a particular amount of missing time:
During what period were the Rocky Mts. formed?
What helps us correlate rock layers better than anything?
What type of unconformity is the most difficult to identify and why?
Disconformity - difficult b/c all of the rock layers are sedimentary.
The actual age of the rock layer:
Absolute age
What index fossil only lived during the cretaceous period?
Inoceramus (clam found in TX)
During what period did dinosaurs become extinct?
What was the very first angular unconformity ever identified?
Siccar Point, Scotland
"New life":
What are the best fossils for correlating rock layers?
Index fossils
What is the half-life of Uranium 238?
4.5 billion years
What is the oldest period of the Paleozoic era?
An unconformity w/ either igneous or metamorphic rock below the unconformity and sedimentary rock above the unconformity:
When was radioactivity discovered? What did this discovery lead to?
1905 - led to the ability to determine absolute age.
When was the Ice Age?
During the Pleistocene epoch
The amount of time it takes for 1/2 of parent isotopes to decay into daughter isotopes:
An unconformity between parallel, sedimentary rock layers:
During what period did birds first form?
Technique used to determine the absolute age of a rock layer:
Radioactive dating
What is the parent isotope of Lead 206?
Uranium 238
What type of unconformity is at the base of the Grand Canyon?
During what period did Pangea begin to break up?
What is the daughter isotope of uranium 238?
Lead 206
What is the parent isotope of Argon 40?
Potassium 40
"Middle life":
States that the present is the key to the past:
During what period did the first fish appear?
When were the oldest rocks on the surface of Louisiana created?
During the Paleocene epoch
Unconformity w/ all sedimentary rocks, but the rocks below the unconformity are tilted @ a different angle than the rocks above the unconformity:
Angular unconformity
What is the half-life of Potassium 40?
1.3 billion years
What time units are eras subdivided into?
When did the Himalayas form?
Eocene epoch
During what period did the first anphibians appear?
List all 4 eras from the oldest to the youngest:
What is the half-life of Carbon 14?
5,730 years
When was the earliest fossil recorded of life?
Precambrian era
During what period did the first land plants appear?
What is the daughter isotope of Potassium 40?
Argon 40
During what period did the first dinosaurs appear?
When were the earliest humans around?
During the Pleistocene (Ice Age) epoch
What are the 3 characteristics of index fossils?
1) Easy to identify.
2) Lived for a relatively short period of geologic time.
3) Lived for only one unit of geologic time (MOST IMPORTANT).
An element with different numbers of neutrons:
During what period did the first reptiles appear?
What is the daughter isotope of Carbon 14?
Nitrogen 14
During what period did the first mammals appear?
Why are the Mississippian and Pennsylvanian periods so important to LA?
Because there was a hot, swampy environment which produced COAL.
When did the earliest shelled animals first appear?
Precambrian era
How many different species of invertebrate and vertebrate marine organisms have been identified based on fossils from the Cane River site?
The vast majority of surface exposures in Louisiana are from what periods?
Tertiary and Quaternary in age (less than 65 million years old)
What do the various fossils at the Cane River Site indicate about its paleoenvironment?
It was probably a shallow ocean with tropical to
subtropical conditions.
Exposed strata or sediments where fossils may be recovered:
Fossiliferous outcrops
How old are the marine fossils from the Cane River Site?
46 million years old
Stable isotope:
Daughter isotope
If a stratigraphic sequence is missing a layer that should be present, then it is said to have:
An unconformity
What were the most abundant invertebrate fossils found at the Cane River site?
Microscopic forms:

Megascopic forms:
The ancient water depth of the Cane River site was probably around ____.
20-50 meters
Most of the rocks exposed at the surface of Earth are ____.
Analysis of radioactive isotopes indicates that a rock contains 150 parent isotopes and 1050 daughter isotopes. If the half life of the isotope is 50 million years, how old is the rock?
150 million years
A radioactive isotope has a half life of 20 million years. If the isotope has decayed four half lives, how old is the rock?
80 million years
A rock contains 1000 parent isotopes. After it has decayed 3 half lives, what is the ratio of parent:daughter isotopes?
125 parents:875 daughters