Shared Flashcard Set

Details

Historical Exam 2
Leithold
65
Geology
Undergraduate 2
02/11/2014

Additional Geology Flashcards

 


 

Cards

Term
Hadean Eon
Definition
4.6 BYA-4.0 BYA
Term
Solar Nebula Theory
Definition
-The solar system formed ~5.0 BYA from a giant spinning cloud of gas and dust or a NEBULA
-Solar winds drove lighter elements and frozen gases outward into space
-Cold matter collected in eddies
-Particles began to accrete and form proto planets, then eventually planets
Term
Heating of Earth
Definition
-Gravitational Contraction
-Bombardment of early earth by meteorites
-Radioactive decay
Term
Gravitational Contraction
Definition
The increased gravity of Earth, due to accretion, caused it to shrink in size which through friction produced great amounts of heat. Raised earths internal temperature to ~1500
Term
Rocky/Terrestrial Planets
Definition
-Mercury, Venus, Earth, Mars
-Composed of rock and metal
-Contain heavier elements
-Average Density 5.1-5.5 g/cm^3
Term
Gaseous/Jovian Planets
Definition
-Jupiter, Saturn, Uranus, Neptune
-Composed of lighter elements, H and He
-Average density 0.7-1.7
Term
Solar Nebula Evidence
Definition
-The orbit of planets around the Sun is on the same plane and in the same direction
-The rotation of most planets is the same direction
-The orbit and rotation of most moons about their planets are the same
Term
Planetary Differentiation
Definition
Shortly after the Earth accreted, the homogenous planet differentiated into layers based on density
Term
Oldest Rocks and Minerals
Definition
-Oldest whole rock is 4.0 Ba
-Oldest mineral grains (detrital zircons) 4.2 Ba
Term
Detrital
Definition
Came from another rock
Term
Moon Formation
Definition
-The moon is believed to have formed when a proto planet collided with the Earth.
-Oldest moon rocks dated 4.4-4.5 Ba
Term
Oldest Meteorites
Definition
Aged 4.53-4.58 Ba also show age of the Solar System
Term
Archean Eon
Definition
-4.0-2.5 Ba
-Earths crust became stable enough that rocks were preserved
-Plate tectonics began
-Atmosphere became oxygenated
Term
Craton
Definition
-Stable interior portion of continents
-Contain the oldest rocks
Term
Orogenic Belts
Definition
The areas that are subject to mountain building (orogeny). They surround cratons
Term
Cordilleran Orogenic Belt
Definition
Runs from Alaska to Patagonia. Means backbone.
Term
Platform
Definition
A pile of sedimentary rocks that cover a craton
Term
Basement Rock
Definition
The stable igneous and metamorphic rocks below the platform in a craton
Term
Shield
Definition
Section of a craton that is exposed. Exposed precambrian rocks.
-Greenstone Belts
-Granite Gneiss Complexes
Term
Greenstone Belts
Definition
-Represent Archean ocean crust
-Composed of mafic rocks that have altered to chlorite
-Form at convergent boundaries (Back Arch Basins)
-Deformed turbidites
-Contain Pillow basalts
Term
Turbidites
Definition
A deposit representative of a turbidity current
Term
Wacke
Definition
Sandstone with a high percentage of mud and other heterogeneous particles. Indicative of Islands
Term
Granite-Gneiss Complexes
Definition
-Felsic
-Early remnants of continental crust
-Surround and intrude Greenstone Belts
-Form at convergent boundaries
Term
Back Arch Basins
Definition
Areas that form behind some subduction zones where the crust is stretched and new basaltic crust is formed in the cracks left behind.
Term
Greenstone Belt Preservation
Definition
-Closing of Back Arch Basins due to compression preserves Greenstone Belts
-Preservation is also due to the difference in plate tectonics in the past
-There where more subduction zones, and convection was more rapid
Term
Photosynthesis
Definition
Isotopic evidence for photosynthesis is evident 3.8 Bya
Term
Cyanobacteria
Definition
-Bacteria that photosynthesize
-Can live almost anywhere there is sunlight and moisture
-Can live alone or in colonies
-Filaments found in fossils 3.4-2.5 Bya
Term
Mats
Definition
Filamentous entangled microorganisms that form on top of sediments
Term
Stromatolite
Definition
Reefs formed by microbial mats that become lithified and grow upward
-Precipitate Calcium Carbonate
-The living part is on the surface
-Have a layered internal structure
-Form in hypersaline environments
-Verycommon from 3.0 Bya till end of the precambrian
Term
Ingredients For Life
Definition
Proteins-Amino Acids
DNA/RNA-Nucleic Acids
Term
Miller-Urey Experiment
Definition
-Produced amino acids in labs
-Mixed CH4, NH4, O2, and N then added a spark (energy)
-Not accurate to early atmospheric conditions
Term
Early Life
Definition
-May have formed in deep ocean vents
-Amino Acids may have come from meteorites (have been found on them)
-Clay minerals have been hypothesized to have served as scaffolding or templates for assembling proteins
-No self replicating life has ever been produced in Laboratory
Term
Early Atmosphere
Definition
-Likely composed of H and He
-Solar winds likely blew those away because earths magnetic field had not yet formed
Term
Second Atmosphere
Definition
Likely composed of volcanic gasses (H, N, H2O, CO2)
-Outgassing due to differentiation
Term
Detrital Pyrite and Uraninite
Definition
-Unstable on earths surface, degrade rapidly if exposed to O2
-If O2 were present in past atmospheres, these would not have survived
-Disappear around 2.5 bya
Term
BIF
Definition
-Altering bands of Hematite, an iron rich mineral, and Chert, a quartz mineral
-Proterozoic
-Marine sediments, formed in oceans
-97% of iron ore in US comes from BIFs
-Indicative of a time when O2 levels began to rise
Term
Red Beds
Definition
-Sandstone and shale beds that are red due to the presence of iron oxide
-terrestrial deposits, common in rivers
Term
Proterozoic Eon
Definition
-2.5-542mya
-Atmosphere rich in O2
-First eukaryotic and multicellular organisms
-first large continent assembled
-First ice age
-Mature siliciclastic sediments accumulate
-Limestone beds become widespread
Term
Laurentia
Definition
-One of the first large continents, assembled by a series of collisions
-Contained much of what is now North America, Greenland and Scotland
Term
Rodinia
Definition
-Supercontinent formed in the mid-Proterozoic when Laurentia collided with other large continents
-Means "Motherland" russian
Term
Acritarchs
Definition
-First eukaryotes, single celled, comparible to modern eukaryotes,
-Eukaryotes reproduce sexually and hav a nucleus
~1.6 Bya
Term
Endosymbiotic Theory
Definition
Organelles such as mitochondria and chloroplasts were once bacteria that took up residence in other cells
-Symbiotic Relationship
-Organelles have cytoplasm and their own DNA
-DNA of mito and plast resemble that of Bacteria
Term
Ediacaran Fauna
Definition
Fossils found in australia of soft bodied organisms, believed to indicate a period of rapid climate change at the end of the Proterozoic
-Evolved in isolation, in melt pools on snowball earth
Term
Ice Ages
Definition
-Sun was weaker during the Precambrian
-Evidence of 2 glaciated periods, 2.4 BYa and 700-600 MYa(snowball Earth)
Term
Glacier
Definition
Rivers of ice that flow by their own weight
Term
Glacial Till
Definition
Poorly sorted sediment that is left behind by receding glaciers
Term
Tillite
Definition
Glacial till that has become lithified
Term
Dropstones
Definition
Sediment carried by icebergs, and deposited elsewhere
Term
Snowball Earth
Definition
700-600 MYa when the earth was entirely glaciated
-Suns luminosity was 90% of its current value
-Lower greenhouse effect
-Rodinia was situated on the equator, which increased earths albedo
-Increased chemical weathering due to the large continent drew down more CO2
-Ended by volcanic eruptions that delivered enough CO2 to swing earth out of ice age
-Shown by glacial tillites and dropstones followed by limestones
Term
Paleozoic Era
Definition
542-251 MYa
-Rodinia breaks up then reforms as Pangea
-Sea level was much higher
-Life in the oceans diversifies and land is colonized
Term
Epeiric Sea
(Epicontinental Sea)
Definition
Seas on top of continental crust
-usually very shallow
-Yellow sea (china) Hudson Bay (canada)
Term
Larry Sloss
Definition
-NA craton has been covered by epeiric seas 6 times during the Phanerozoic Eon
-Shoreline transgressed
-Deeper water facies deposited on shallower water facies
-Observed 6 transgressive sequences recording sea level rise separated by unconformities
Term
Transgression
Definition
A landward shift of shoreline due to sea level rise
Term
Cratonic Sequence
Definition
A layer of Limestone on top of mudstone on top of sandstone records transgressions
Term
Local Sea Level Change
Definition
Can occur because the level of the sea bed is changed by relative accumulation or by sediment compaction or by fault movement
Term
Global (Eustatic) Sea Level Change
Definition
-The volume of water stored in oceans changes
-The capacity of the ocean basins changes
-Rising at 3.5 mm/yr.
-Warming of oceans can cause water to expand
Term
Chemical Weathering
Definition
Chemical weathering of silicate minerals such as feldspars scrub CO2 out of the atmosphere
-Weathering produces bicarbonate ion which is transported to and stored in the ocean
Term
Uplift
Definition
Rising coastlines near convergent boundaries can cause local regression of sea level (Alaska)
Term
Subsidence
Definition
Land sinking due to tectonics or oil extraction causes transgression (Galveston, TX)
Term
Cambrian Explosion
Definition
-Around 535 mya variety of fossils diversifies rapidly
-Almost all phyla of invertebrates appear
-Hard and Soft bodied animals preserved
Term
Cambrian Explosion Explanations
Definition
1. Increased O2 levels (not likely)
2. The expansion of habitats due to transgression
3. Advent of predation
Term
Biomineralization
Definition
-organisms produce minerals to harden their bodies
-Began at the end of the proterozoic
Term
Anomilocaris
Definition
-(Strange Shrimp) Early predator found in Burgess Shale
-Got as big as 1 meter
-Preyed on trilobites
Term
Predation
Definition
-Most likely explanation of the Cambrian Explosion
-Lead to development of external skeletons and improved locomotion
-Accelerated the pace of evolution
Term
Burgess Shale
Definition
-Discovered in 1909 by Charles Walcott in BC
-Mid-Cambrian in age
-Contains unusual assemblage of soft bodied organisms
-Preserved by a piece of reef that collapsed and was buried in mud in deep O2 deficient waters
Supporting users have an ad free experience!