Earth's History

superposition

• the principle that in undisturbed rock layers, the oldest rocks are on the bottom

• the concept that all rocks are formed at the same time

• the idea that younger rocks can be found below older rocks

• the theory that rocks are formed from molten lava

half life

• Time it takes for half of an isotope to decay

• The time required for a full decay of an isotope

• The period during which an isotope remains stable

• The time it takes for an isotope to double in quantity

correlation

• a mutual relationship or connection between two or more things

• a statistical measure that describes the size and direction of a relationship between two or more variables

• a method of organizing data into categories

• a technique used to analyze the frequency of events

isotope

• Atoms of the same element that have different numbers of neutrons

• Atoms of different elements that have the same number of protons

• Atoms that have the same mass but different charges

• Atoms that are chemically identical but physically different

index fossil

• fossils of widely distributed organisms that lived during only one short period

• fossils that are found only in a specific geographic area

• fossils that are millions of years old and found in multiple layers of rock

• fossils that represent a single species that existed for a long time

Describe how life changed the Earth's early atmosphere.

• Photosynthetic organisms released oxygen into the atmosphere.

• Volcanic activity decreased the amount of carbon dioxide.

• Meteor impacts increased nitrogen levels in the atmosphere.

• Decomposers eliminated all greenhouse gases.

erosion

• A condition where the earth's surface is built up by volcanic activity.

• A process in which the earth's surface is worn away by the action of water and wind.

• A phenomenon that causes the earth's surface to remain unchanged over time.

• A type of soil formation that occurs in dry climates.

unconformity

• a place where an old, eroded rock surface is in contact with a newer rock layer- shows a gap in the rock record

• a type of rock that forms from volcanic activity

• a geological feature that indicates a fault line

• a layer of sediment that has been compacted over time

original horizontality

• Principle stating that sedimentary rocks are deposited in horizontal or nearly horizontal layers.

• Principle stating that all rocks are formed from molten lava.

• Principle stating that sedimentary rocks are formed from volcanic activity.

• Principle stating that rocks are always found in a vertical position.

uplift

• lift up; elevate; raise

• bring down; lower; drop

• ignore; neglect; dismiss

• flatten; level; smooth