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30 Cards in this Set
- Front
- Back
Scientists look at what evidence to determine the geologic time scale?
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fossils
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The process responsible for forming altered hard part fossils is called what?
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permineralization
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What two types of fossils contain no bone or shell material?
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molds and casts
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In an original preservation fossil, no ______________ has taken place.
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decomposition
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This type of time frame in measured in tens of millions of years.
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epoch
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Eras are defined as the differences in life forms found in ____________.
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rocks
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This theory states that the processes occurring today have been occurring ever since Earth was created.
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uniformitarianism
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In cross-cutting relationships, rock cutting through another body of rock must be ___________ than the rock being cut through.
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younger
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Unconformity is caused by what two processes?
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weathering and erosion
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Paleozoic is a Greek word meaning what
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old life
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What percentage of all life forms that ever existed on Earth are now extinct?
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10%
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Original preservation fossils usually occur when there is a lack of ____________ in the decomposition process.
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oxygen
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What type of fossils are used to correlate rock layers over large areas?
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index fossils
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In the process of permineralization, what are the pore spaces of rocks filled with?
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minerals
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What type of rock do molds usually form in?
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sedimentary
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Evidence or remains of once living plants or animals are called ____________.
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fossils
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In altered hard part fossils, the _____________ has been completely removed or decayed
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organic material
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How long ago do scientists theorize Earth was formed?
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4.6 billion years ago
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___________states that the oldest rocks layers are at the bottom, and each
consecutive layer going up is younger. |
Law of Superposition
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____________ is a gap in the rock record caused by erosion or weathering.
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unconformity
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Mountain building, erosion, and sea floor spreading are all examples of ________________.
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uniformitarianism
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Uniformitarianism states that all processes on Earth have continuously been occurring, and only __________, ___________, and ____________ with which these processes have occured has changed.
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rate, intensity, and scale
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The record of the Earth’s history is called the ______________.
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geologic time scale
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Eons are measured in what type of units?
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billions of years
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What is the smallest division in the geologic time scale?
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epoch
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Zoic means __________.
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of life
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The oldest rock layers are found near the __________.
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bottom
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Paleo means ___________.
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young
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Casts are basically molds filled up with ____________.
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sediment
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______ % of all life forms ever to exist on Earth are now extinct.
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90
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