More of Earth's History
Terms
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- hiatus
- a break or gap in the rock record
- In undistributed layers of rock where are the oldest layers?
- at the bottom
- What are some evidence of events on earth?
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igneous intrusions and extrusions
faults, joints, folds
internal characteristics - What isotopes are useful in dating?
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Carbon-14
Uranium-238 - What steps combine in seqwuence to produce an unconformity?
- uplift, erosion, subsidence, and depostition
- What are the ages of rock compared to their surronding?
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rock fragments found in larger rock masses are older the n surronding rock
cracks viens and mineral cement are younger then surronding rock - What are the perferable types of index fossils?
- lived over the entire earth for relatively short periods of time
- What is the most reliable fossil evidence?
- index fossils
- vien
- a mineral deposit that has filed a crack
- What isotope does not combine chemically with any other element?
- argon 40
- What species first occured in the Paleozoic era?
- intervertebrates, fishes, amphibians, vertebrates, and land plats and animals
- Why are unconformities useful?
- they indicate a geologic event of some magnitude took place
- Explain the history of the atmosphere
- 500 million years ago the earth's interior was solid, earth heated and melted the solid materials, as earth cooled the crust developed
- nonconformity
- interfaces formed when sedimentary rocks are deposited on top of an eroded surface of igneous rocks
- How can potassium 40 be used to date a rock?
- by comparing the amounts of argon 40 and potzassuium 40, the age can be determined
- When using the potasium- argon dating system which determines the age of the rock?
- The more Agron 40 in the rock, the older the rock
- How was earth born?
- as a cloud of gases and dust left over fro m the creation of the sun
- What was the primary source of gases of Earth's earliest atmosphere?
- outgassing by volcanoes.
- How long have have humans been in existence?
- .04% of the 4.5 billion years
- What does the mesozoic era provide evidence of?
- dinosaurs, earliest birds and mammals
- What is necessary for fossils to survive?
- must be buried soon after death and have hard shells, bones,m or teeth
- angular unconformities
- tilted, folded,or faulted rocks that have been eroded and covered again
- what determines the geographic history of an area?
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fossil evidence
age of rocks
erosional record - parallel unconformities
- occur when parallel rock layers of different ages are seperated by an erosional surface