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30 Cards in this Set

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