Fossil Types
Dating Rocks
Events in Geologic Time
The Geologic Time Scale
Miscellaneous
100
The preserved remains or traces of an organism.
What is a fossil.
100
The age of a rock compared to other rocks.
What is relative age.
100
An event in which many types of living things become extinct at the same time.
What is a mass extinction.
100
A record of the life forms and geologic events in Earth's history.
What is the geologic time scale.
100
The extinction of dinosaurs gave warm-blooded vertebrates called ___________ a chance to become abundant.
What are mammals.
200
A hollow imprint that shows the shape of an organism.
What is a mold.
200
Useful fossils that help to tell the relative ages of the rocks around them.
What are index fossils.
200
The end of one era and the beginning of a new era is usually caused by a ________ _______________ .
What is a mass extinction.
200
Scientists hypothesize that Earth formed at the same time as the other planets and the sun, roughly _________ billion years ago.
What is 4.6
200
What are the best types of rocks for radioactive dating?
What are igneous rocks.
300
An example of this type of fossil would be footprints.
What is a trace fossil.
300
An intrusion in always _________ than the rocks around it.
What is younger.
300
The subdivisions of eras are called ______________ .
What is periods.
300
Reptiles, such as dinosaurs, were so successful during the _______________ Era that the time is often called the age of Reptiles.
What is Mesozoic.
300
Life on Earth first began in the ______________ Period.
What is Precambrian.
400
A fossil formed when minerals replace all or part of an organism.
What is a petfrified fossil.
400
The method used to determine the absolute age of rocks.
What is radioactive dating.
400
What do most scientists think caused the mass extinction at the end of the Cretaceous Period?
What is an object from space struck Earth.
400
Jawless fish were earth's first ______________, or animals with backbones.
What are vertebrates.
400
A gap in the geologic record where some rocks layers have been lost due to erosion.
What is an unconformity.
500
The state fossil of New York.
What is a trilobite.
500
Explain how the Law of Superposition is used to determine the relative ages of sedimentary rock layers.
What is the oldest layer is that the bottom, and each higher layer is younger than the rocks below it.
500
Earth's atmosphere, oceans, and continents began to form during the first several hundred millions years of ______________ .
What is Precambrian Time.
500
Certain ammonites are used an __________ ___________ because they lived in many different areas but only for a brief time.
What are index fossils.
500
The present day is part of the ____________ Era.
What is Cenozoic.
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