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Historical Geology 1304
miderm
79
Geology
Undergraduate 1
03/10/2011

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Term
stratigrophy
Definition
study of stratified rock- geometric relations, composition, origins, and age relations
Term
stratographic units
Definition
include strata, groups of adjacent strata, that are distinguished by physical, chemical or paleontological properties; also incluse units of time based on ages of strata
Term
correlation
Definition
demonstrating correspondance between geographically seperated parts of a stratigraphic unit
Term
lithologic correlation
Definition
lateral continuity
Term
temporal correlation
Definition
widely seperated bodies of rocks are the same age
Term
time-rock unit
Definition
all strata that was deposited during a particular interval of time
Term
time unit
Definition
interval at which a time rock unit was formed
Term
erathems
Definition
eras are the time units that correspond to it; for the Phanerozoic eon, these are paleozoic, mesozoic, and cenozoic
Term
boundary stratotype
Definition
boundry between two systems, series, or stages
Term
bio-stratographic units
Definition
units of the rock record that are defined and characterized by ther rock content
Term
zone
Definition
body of rock whose lower and upper boundaries are based on the ranges of one or more taxa- usually species- in the stratigraphic period
Term
index fossils or guide fossils
Definition
-abundant enough in the stratigraphic record to be found easily
-easily distinguished from other taxa
-wide spread and can be used to correlate rocks over a large area
-occurs in many type of sedimentary rocks- found in many places
-it is used to define a zone
Term
magnetic stratigraphy
Definition
evaluating magnetic properties of rocks
Term
chron
Definition
normal and reversed intervals
Term
rock units
Definition
groups, members, super groups
Term
lithology
Definition
physical and chemical characteristics of rock
Term
stratigraphic section
Definition
local outcrop of a formation that displays a vertical sequence
Term
type section
Definition
a stratigraphic section designated at a particular locality where the unit is well exposed
Term
regression
Definition
seaward migration of a shoreline
Term
transgression
Definition
sea spreads landward
Term
facies
Definition
the set of characteristics of a body of rock that represent a particular depositional environment
Term
radioactive decay
Definition
atoms change to atoms of another element by releasing subatomic particles or energy
Term
isotopic dating
Definition
measuring the father and daughter isotope in rocks
Term
radio carbon dating
Definition
isotopic dating that makes use of carbon 14
Term
cosmogenic dating
Definition
particle strike certain atoms in crystalline materials at earths surfacs causing them to fragment and form lighter nuclei
Term
thermoluminescence dating
Definition
when heat is used to drive out electrons
Term
optical dating
Definition
when light is employed
Term
event stratigraphy
Definition
instantaneous formation of a surface and sudden relocations of shorelines
Term
markerbed
Definition
bed of sediment that looks like a layer of paint
Term
seismic stratigraphy
Definition
seismic reflections generated when artificially produced seismic wave bounce off physical discontinuities within buried sediments
Term
eustatic changes
Definition
global changes in sea level
Term
sequences
Definition
used to divide stratigraphic record
Term
homology
Definition
plants or animals that have same ancestral origins but serve different functions
Term
vestigial organs
Definition
organs that serve no apparent purpose but are used in other creatures
Term
chemical reservoirs
Definition
bodies of chemical entities that occupy particular spaces
Term
flux
Definition
reservoirs gain or lose contents
Term
negative feedback
Definition
opposing the expansion of a reservoir until fluxes to and from this reservoir are in balance
Term
positive feedback
Definition
accelerating a change instead of breaking it
Term
reduced carbon
Definition
contain small amounts of oxygen
Term
anoxic
Definition
absence of oxygen
Term
carbon isotopes
Definition
record the cycling of organic carbon
Term
isotopes in limestone or deep sea sediments
Definition
record changes in rates of carbon burial
Term
carbon and sulfur burial
Definition
enlarges atmospheres oxygen reservoir
Term
methane hydrate
Definition
methane frozen within a range of water molecules
Term
hold Co_2 levels in check
Definition
negative feedbacks
Term
oxygen isotope ratio inskeletons
Definition
reflect temperatures
Term
oxygen isotopes vary with
Definition
salinity
Term
glaciers lock up
Definition
oxygen 16
Term
cratons
Definition
large portions of continents that have not undergone substantial tectonic deformations since early Paleozoic time
Term
Precambrian shield
Definition
precambrian portion that is exposed at earths surface
Term
redshift
Definition
evidence that the universe is expanding
Term
early melting produced
Definition
layered earth
Term
moon formed from
Definition
a collision
Term
oceans water and salts came from
Definition
volcanoes, comets, and rocks
Term
earths atmosphere mostly came from
Definition
within
Term
felsic crust formed by
Definition
melting of oceanic lithosphere
Term
reveals how earliest crust formed
Definition
igneous activity
Term
archean continents remained small because of
Definition
earths hot interior
Term
protocontinents
Definition
numerous felsic rocks that emerged in archean time eventually coalesced to form small continents called
Term
terrane
Definition
distinctive region of earths crust that has behaved as a coherent crustal block
Term
greenstone belts
Definition
sit in masses of high-grade metamorphic rocks of felsic composition
Term
banded iron formations
Definition
cherts and iron rich sedimentary rocks
Term
2.7 and 2.3 billion years ago
Definition
most metamorphic episodes occurred in many parts of the world
Term
4.5 billion years ago
Definition
life appeared on earth
Term
100 million years after earth came into being
Definition
living things could not have existed until
Term
along mid ocean ridges
Definition
life may have originated along
Term
3 billion years ago
Definition
cratons of modern proportions formed about
Term
orogen
Definition
body of rocks deformed by an oregeny (ex southern Africa)
Term
Proterozoic time
Definition
glaciation was wide spread in the
Term
acritarchs
Definition
single-celled algae conspicuous inProterzoic rocks
Term
750 million years ago
Definition
most ancient animal like unicellular organisms fluorished
Term
Neoproterozoic time
Definition
animals probably originated during the... 30 million years ago
Term
ediacara fauna
Definition
oldest known undoubted adult animals preserved in fossil reord of the... leaf shaped fossils 570 million years agoth
Term
three major animal groups (Proterozoic eon)
Definition
lophotrochozoans, ecdysiozoans, and the deutorozoans
Term
proterozoic time
Definition
world wide glaciation
Term
favored eukaryotes
Definition
build up of atmospheric oxygen
Term
paleoproterozoic
Definition
build up of oxygen important- may have promoted success of eukaryotic algae
Term
continental accreation
Definition
expanded Laurentia during proterozoic timeGe
Term
Grenville orogeny
Definition
built mountains in eastern north america
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