Studied by 11 people
Orogeny
Period of mountain building in which tectonic forces cause rocks to be faulted, folded and/or metamorphosed
Shield
Ancient cores of continents made of Precambrian igneous & metamorphic rocks
Mold
Empty cavity formed when the hard parts of a buried organism are dissolved/reacted away
Trace Fossil
Indirect evidence for ancient life such as footprints, trails or burrows
Dendrochronology
Study of tree rings to calculate dates of past events and to determine climatic changes in the past
Varves
Alternating bands of light- and dark-colored sediments deposited respectively during summer and winter in large lakes
Paleozoic
Era of "Ancient Life"
Mesozoic
Era of "Middle Life"
Cenozoic
Era of "Recent Life"
Phanerozoic
Eon of "Visible Life"; Eon of multicellular organisms with hard parts
Proterozoic
Eon of one-celled organisms
Archean
Eon of "Ancient" Time
Hadean
Eon of "Hellish" Time
Geologic Time Scale
Chart used to describe earth's history by dividing it into various eons, eras, periods & epochs, originally based only on the fossil record
Cast
A 3-D copy of the hard parts of an organism formed when the hard parts of a buried organism are dissolved/reacted away and the resulting cavity is filled with sediments
Stromatolites
The most common Precambrian fossils (of algae) found in numerous places around the world and dating back hundreds of millions to billions of years
Mass extinction
When many types of living things (species) disappear from earth at the same time
Evolution
Change in living things through time
Paleontologist
Scientist that studies fossils and ancient organisms
Petrified
Turned to stone; fossilized in rock
Principle of Superposition
In undisturbed sedimentary rocks, the oldest rocks are on the bottom and the youngest are on the top
Principle of Cross-Cutting Relationships
Younger features cut across or through older features
Principle of Contact Metamorphism
Rocks metamorphosed by the magma are older than the intrusion or lava flow, unmetamorphosed rocks are younger than the lava flow
Principle of Fossil Succession
Fossils and the rocks they are found in can be arranged in a definite order according to their age
Principle of Original Horizontality
Sediments are deposited in originally flat layers
Daughter Isotope
Isotope formed from the decay of an unstable isotope
Uniformitarianism
Fundamental principle of geology that states the processes which occur on Earth today are the same processes that occurred in the past; the present is the key to the past
Correlation
Matching a rock layer or rock unit in one place with the same rock layer in another place using rock type, thickness, fossils, etc.
Unconformity
Any break in the rock record when erosion took place instead of deposition
Relative Date
The age of a rock formation or event compared to the surrounding rock formations or events
Fossils
Remains or traces of ancient life
Index Fossils
Fossils that are widespread over a large area of earth and only existed for a short amount of time and are used to give approximate numerical dates to rock formations and geologic events
Radiometric Date
The absolute age of a rock or mineral calculated using the ratios of parent and daughter isotopes
Absolute Date
Date that gives the number of years that have passed since a rock formed or an event occurred
Radioactive Decay
The spontaneous breaking apart of nuclei of atoms through time to form new & different atoms
Parent Isotope
An unstable isotope that has not yet decayed
Half life
The time it takes half the atoms of a parent isotope to decay into atoms of the daughter isotope
Isotope
Atoms that have the same number of protons, but different numbers of neutrons
Eon
The largest time expanse in geologic time consisting of 100s of millions of years
Epoch
The smallest time expanse in geologic time consisting of millions of years
Era
The second largest time expanse in geologic time consisting of many tens of millions of years
Period
The second smallest time expanse in geologic time consisting of tens of millions of years
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Flashcard (95)