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Geology
Dr. Kritizch
65
Geology
Undergraduate 3
10/06/2010

Additional Geology Flashcards

 


 

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Term
Metamorphic
Definition
refers to solid-state changes to rocks in Earth's interior. Produced by increased heat, pressure, or the action of hot reactive fluid
Term
Pressure during metamorphism
Definition
confining pressure applied equally in all directions, to depth within the Earth. High-pressure minerals more compact/ more dense
Term
Metamorphic Rock Characteristics
Definition
depends on: parent rock composition, temperature and pressure
Term
Parent Rock Composition
Definition
resulting metamorphism rock will have similar composition to parent rock
Term
Foliation
Definition
planar rock texture of aligned minerals produced by differential stress. Types:Slaty,Phyllitic,Gnesissic,Shistose
Term
Temperature during metamorphism
Definition
heat comes from Earth's deep interior, usually the deeper the rock the hotter, if range exceeded, new minerals result
Term
Contact Metamorphism
Definition
a type of metamorphism, high temperature is dominant factor, produces non-foliated rocks, low pressure. Occurs adjacent to magma bodies intruding cooler country rock
Term
Regional metamorphism
Definition
a type of metamorphism, high pressure is dominant factor, results in rocks with foliation
Term
Non-foliated Rocks
Definition
Marble-recrystallized limestone
Quartzite-recrystallized sandstone
Term
Foliated metamorphic rocks
Definition
Slate-splits along parallel plates
Phyllite, Schist, Gneiss
Term
Geophysics
Definition
the branch of geology that studies the interior of the Earth
Term
Seismic waves 3 main zones
Definition
Crust, mantle, core
Term
Seismic waves
Definition
or vibrations from a large earthquake will pass through the entire Earth
Term
Seismic Reflection
Definition
the return of some waves to the surface after bouncing off a rock layer boundary
Term
Seismic refraction
Definition
bending of seismic waves as they pass from one material to another having different seismic wave velocities
Term
Crust
Definition
is the outer layer of rock that forms a thin skin on Earth's surface
Term
Mantle
Definition
is a thick shell of dense rock that separates the crust above from the core below
Term
Mafic
Definition
oceanic crust, composed primarily of basalt and gabbro
Term
Felsic
Definition
continental crust, with an average composition similar to granite
Term
Ultramafic
Definition
higher seismic wave velocity of mantle vs. crustal rocks indicative of denser, composition
Term
Lithosphere
Definition
crust and upper mantle together, the brittle outer shell of the Earth that makes up the tectonic plates
Term
Seismic shadow zones
Definition
the core that does not receive seismic waves due to a large earthquake
Term
P-wave shadow zone
Definition
explained by refraction of waves encountering core-mantle boundary
Term
S-wave shadow zone
Definition
suggests outer core is a liquid
Term
Isostasy
Definition
equilibrium of adjacent blocks of brittle crust "floating" on upper mantle. Thicker blocks of lower density crust have deeper "roots" and float higher (mountains)
Term
Isostatic adjustment
Definition
rising or sinking of crustal blocks to achieve isostatic balance
Term
Crustal rebound
Definition
rise of crust after ice sheet removal
Term
Fossils
Definition
meaning "dug up", remnants or traces of ancient living organisms
Term
Paleontology
Definition
study of fossils
Term
Sedimentary rocks
Definition
most fossils found in sediment or
Term
Faunal succession
Definition
fossil species succeed each other in a definite and recognizable order,
Term
Charles Darwin
Definition
wrote the Origin of Species, "natural selection",
Term
Extinction
Definition
last members of a species die, 99.9% of living species have died
Term
cyanobacteria
Definition
fossils of blue-green algae; 3.5 billion yrs ago
Term
James Hutton
Definition
"father of geology" geologic features could be explained through present-day processes
Term
Contacts
Definition
surfaces separating successive rock layers (beds)
Term
Formations
Definition
bodies of rock of considerable thickness with recognizable characteristics allowing them to be distinguished from adjacent rock layers
Term
Stratigraphy
Definition
the geologic specialty concerned with interpretation of geologic events based on relationship of rocks
Term
Stratigraphic Principles
Definition
Original horizontality; superposition, lateral continuity, cross-cutting relationships
Term
Original horizontality
Definition
beds of sediment deposited in water are initially formed as horizontal or nearly horizontal layers
Term
Superposition
Definition
within an undisturbed sequence of sedimentary or volcanic rocks, layers get younger from bottom to top
Term
Lateral continuity
Definition
original horizontal layer extends laterally until it tapers or thins at its edges
Term
Cross-cutting relationships
Definition
a disrupted pattern is older than the cause of the disruption
Term
Intrusions and faults
Definition
are younger than he rocks they cut through
Term
Baked contacts
Definition
contacts between intrusions and surrounding rocks, where surround rocks have experienced contact metamorphism
Term
Inclusions
Definition
fragments embedded in host rock are older than the host rock
Term
Relative age
Definition
the order of events or objects, from first (oldest) to last (youngest)
Term
Numerical age
Definition
the age of events or objects, expressed as a number or numbers
Term
Unconformity
Definition
a surface (or contact) that represents a gap in the geologic record
Term
Disconformity
Definition
an unconformity in which the contact representing missing rock layers separates beds that are parallel to each other
Term
Angular unconformity
Definition
an unconformity in which the contact separates overlying younger layers from eroded tilted or folder layers
Term
Nonconformity
Definition
an unconformity in which an erosional surface on plutonic or metamorphic rock has been covered by younger sedimentary or volcanic rock
Term
Fossil assemblages
Definition
groups of different fossil species
Term
Correlation by fossils
Definition
fossil common in sedimentary rock
Term
Standard geologic time scale
Definition
worldwide relative time scale; subdivides geologic time based on fossil assemblages
Term
Precambrian
Definition
vast amount of time prior to the Palezoic era; few fossils preserved
Term
Paleozoic Era
Definition
"old life" 545 m.y.a; 95% of existing species die out; appearance of complex life; many fossils
Term
Mesozoic era
Definition
"middle life" 250 m.y.ago; dinosaurs abundant on land; period ended by mass extinction; 75% of species die out
Term
Cenozoic era
Definition
"new life" 65 m.y.ago; mammals and birds abundant
Term
Pleistocene Epoch
Definition
most recent ice ages occurred of the Quaternary Period
Term
Holocene Epoch
Definition
the recent Epoch of the Quaternary Period of the Cenozoic Era
Term
Numerical dating
Definition
puts absolute values on the ages of rocks and geologic time periods
Term
Isotope
Definition
same number of protons, different numer of neutrons
Term
Radioactive decay
Definition
spontaneous nuclear change of isotopes with unstable nuclei
Term
Half-life
Definition
the rate of proportional decay for isotopes
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