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History of Earth
Chapter 8+9
55
Science
7th Grade
01/25/2012

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Term
Paleontology
Definition
The science that deals with the study of past life.
Term
Uniformitarianism
Definition
The idea that the same geologic processes that shape the Earth today have been at work during all of Earth's history.
Term
Catastrophism
Definition
The idea that geologic change happens suddenly.
Ex: Volcanic eruption, tsunami, asteroid hitting Earth.
Term
Relative Dating
Definition
Determining whether an object (like a rock layer) or event is older or younger than other objects.
Term
Metamorphic Rock
Definition
Rocks that are formed when one type of rock is changed into another type of rock by temperature or pressure
Term
Metamorphic Rock
Definition
Rocks that are formed when one type of rock is changed into another type of rock by temperature or pressure
Term
Metamorphic Rock
Definition
Rocks that are formed when one type of rock is changed into another type of rock by temperature or pressure
Term
Igneous Rock
Definition
This type of rock forms when magma cools.
Term
Sedimentary rock
Definition
This type of rock forms when fragments from other rocks get cemented together. Usually this rock forms in layers.
Term
Weathering
Definition
The breaking down of rocks into smaller pieces, can be caused by physical or chemical processes.
Term
Erosion
Definition
The process that moves sediment from one place to another. This can be caused by water, wind, ice, or gravity.
Term
Deposition
Definition
This is the process where materials (like sediment) is laid down or dropped.
Term
Sediment
Definition
Composed of rock fragments, material dissolved in water, or biological (plant or animal) debris.
Term
Superposition
Definition
A principle that states that younger rocks lie above older rocks, if the rock layers have not been disturbed.
Term
Unconformity
Definition
A surface of rock that represents a missing part of the geologic record.
Term
Folding
Definition
This process occurs when rock layers bend and buckle from forces inside the Earth.
Term
Tilting
Definition
This process occurs when forces inside the Earth slant rock layers.
Term
Fault
Definition
This is a break in the Earth's crust along which blocks of rock slide relative to one another.
Term
Intrusion
Definition
Molten rock from the Earth's interior that squeezes into existing rock and cools.
Term
The Law of Cross Cutting Relationships
Definition
Principle that states "A fault or body of rock, such as an intrusion, is younger than any rock layer that it cuts through".
Term
Absolute Dating
Definition
Finding the age of an object b determining the number of years that is has existed.
Term
Radioactive Decay
Definition
The breakdown of a radioactive isotope into a stable isotope of the same element or another element.
Term
Radiometric Dating
Definition
Determining the absolute age of a sample based on the ratio of parent material to daughter material.
Term
Half-Life
Definition
The time needed for one half of a radioactive sample to decay.
Term
Fossil
Definition
The trace or remains of an organism that lived long ago, usually preserved in sedimentary rock.
Term
Amber
Definition
Hardened tree sap.
Term
Petrification
Definition
The filling or replacement of an organism's tissues with minerals that have a different chemical composition than the original tissues did.
(Turning a dead organism into "stone")
Term
Trace Fossils
Definition
Fossilized evidence of animal activity. Ex: footprints, burrows, coprololites.
Term
Mold
Definition
The impression left in sediment or rock where a plant or animal was burried.
Term
Cast
Definition
This type of fossil forms when sediment fills a mold and becomes a rock.
Term
Fossil Record
Definition
The history of life in the geological past as represented by traces or remains of living things (fossils).
Term
Index fossil
Definition
Fossils of organisms that lived for a relatively short, well defined, geological time period. These are helpful in dating rock layers.
Term
Plate Tectonics
Definition
The theory that explains how Earths' tectonic plates move and change shape.
Term
Lithosphere
Definition
The thin, cool, "skin" of the Earth.
Term
Mantle
Definition
Thick layer of solid rock that is under the crust of the Earth. It drags on the bottom of tectonic plates as it moves.
Term
Convergent Boundary
Definition
Plate boundary that forms when two tectonic plates move towards each other.
Term
This type of plate boundary often forms mountain ranges and volcanoes.
Definition
Convergent boundary
Term
Divergent Boundary
Definition
This type of plate boundary forms when two tectonic plates move away from each other.
Term
This type of plate boundary often forms rifts, oceans, or seas.
Definition
Divergent Boundary
Term
Transform Boundary
Definition
This type of plate boundary forms when two tectonic plates slide horizontally past one another.
Term
The movement of this type of plate boundary causes earthquakes.
Definition
Transform boundary
Term
Continental Drift
Definition
The term used to describe how continents have moved around Earth's surface throughout Earth's history.
Term
Pangaea
Definition
One large, supercontinent that existed on Earth 245 million years ago.
Term
Geologic Time Scale
Definition
The name for the scale that divides Earth's 4.6 billion years of history into distinct intervals of time.
Term
Extinction
Definition
The death of every member of a certain kind of organism.
Term
Precambrian Time
Definition
The time from the formation of Earth, 4.6 billion years ago, until about 542 million years ago. Life on Earth began during this time.
Term
Paleozoic Era
Definition
542 million years ago-251 million years ago. Contained the "Cambrian Explosion" and the "Permian Extinction".
Term
Mesozoic Era
Definition
251 million years ago-65 million years ago. The "Age of Reptiles". Contained the Cretaceous-Tertiary (K-T) extinction.
Term
Cenozoic Era
Definition
65 million years ago-today. "The Age of Mammals". Many climate changes happened during this Era, including Ice Ages.
Term
The Permian Extinction
Definition
Largest mass extinction in Earth's history. This happened in the Paleozoic Era.
Term
How could a meteor impact have cause a world-wide mass extinction?
Definition
The impact would create enough dust to fill the atmosphere and block out the sun. No sun = No plants. No plants=No plant eaters, etc...
Term
What types of rocks are the best to find fossils?
Definition
Sedimentary Rock
Term
What type of rock is formed from the recrystalization of other rocks?
Definition
Metamorphic Rocks
Term
During which era did the Cretaceous-Tertiary extinction occur?
Definition
The end of the MESOZOIC era.
Term
During which era did the Permian extinction occur?
Thiswas the Earth's largest mass extinction.
Definition
The PALEOZOIC era.
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