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GEOSC 001 EXAM 3
Terms in this set (112)
evidence for a meteorite impact killing off the dinosaurs comes from?
iridium in clay layers that are 65 million years old
African rifting and hominin evolution suggestions
1.) plateau uplift influenced the environment which supported hominin evolution - climate mainly
2.) localized development of rift valleys created environments favorable to hominin evolution - climate and physical environment
what percentage of all the earth's water is found in lakes and streams?
what percentage of the earth's water is found in groundwater?
Importance of groundwater
-Source of drinking water for 50% of US population
-Source of 40% of irrigation water
-Provides 25% of industry's water needs"
zone of aeration
unsaturated region above the water table
the upper boundary of the zone of saturation
zone of saturation
the underground region where all of the pores are filled with water
a porous and permeable rock layer or sediment through which water flows easily
An impermeable rock layer or sediment through which water cannot flow
which is the better aquifer, sandstone or shale?
If a rock formation were made of the styrofoam used in coffee cups, would the formation be an aquifer or an aquitard?
an aquitard, because the porosity of Styrofoam is high but the permeability is low
what drives the natural flow of groundwater?
water pressure and gravity
where would you expect to find evidence of early life of earth?
ancient sedimentary rocks preserved in parts of the continents called cratons
point at which we see the oldest fossil evidence for life
3.465 Ga ( cyabobacteria fossils)
the "snowball earth" scenario
-end of the proterozoic
- 550 Mya
Permian Extinction Event
- Also known as "The Great Dying"
-96% of marine species extinct
-70% of terrestrial vertebrate species extinct
-Only 25% of all species survived
which of the following ay have caused the Permian extinction?
flood basalt volcanism and breakup of pangaea
proposed causes of the permian exntinction
-global climate cahnge from release of the methane hydrates
-massive flood basalt eruptions from the Siberian traps
-shifts in oceanic circulation due to Pangaea
life forms change in response to changes in their environments
-organism produce more offspring than can survive to reproduce
-every individual is unique
-those individuals that are best adapted to their surrounding will survive
-dust cloud blocking sunlight and inhibiting photosynthesis
-sulfuric acid aerosols injected into the stratosphere leading to 10-20% reduction in sunlight
-firestorms increase CO2 and greenhouse effect
Through Earth's history, what process has been most responsible for changes in habitat?
the ________ is boundary between the saturated and unsaturated zone in the subsurface
what would make a better aquitard, vesicalar basalt, conglomerate, quartzite, or sandstone?
relative sizes of earth's water reservoirs
oceans - 95.96%
glaciers and polar ice - 2.97%
underground waters - 1.05%
lakes and rivers - 0.01%
-volume of water flowing in a certain time is proportional to vertical drop + flow distance
-discharge from an aquifer is proportional to the permeability
a well in which the water spontaneously rises above the water table due to hydraulic pressure
what rock type typically serves as the best filter for groundwater that is contaminated with bacteria?
Springs form where
A perched aquifer intersects a hill slope
an artesian well flows because
-The pressure surface is above the height of the well
-the potentiometric surface is above the height of the well
a land surface consisting of many sinkholes and surface depressions where bedrock is made of limestone or dolomite
there are no active volcanic fields in the appalachian mountains/ so why are there hot springs?
water is circulating deep in the crust along faults where it heats up
how many high tides does the new jersey shore experience each day?
Tidal Drag Slows Down the Earth's Rotation!
cambrian (560 Ma) 425 days
permian (280 Ma) 395 days
today 365 days
what kind of rock forms at a delta like the mississippi delta?
why do we not find mississippi type deltas on the atlantic coast of the US?
the atlantic ocean currents are so strong that they redistribute river sediment before it accumulates in a delta
coastal plains and sandbars
passive continental margins
sand supply and high
Over time, do offshore currents smooth or roughen rocky shorelines?
three approaches to saving coastal areas
- hard stabilization
- beach nourishment
warmest period during earth's history
how many periods of significant glaciation has earth experienced?
the oldest known ice age happened in...
How might periods of supercontinent formation and rifting relate to ice ages?
-extremely cold wintry conditions can develop more easily in the middle of supercontinents
-rifting leads to new oceans, which influence temp
volcanism is more active during periods of rifting and this release CO2
climate and plate tectonis
concentration of continents at poles rather than equator might induce ice age since landmasses absorb much sunlight at equator
the greenhouse effect
-high energy radiation is transmitted from sun to earth
-earth reflects lower energy radiation towards outer space
-lower energy radiation is absorbed by greenhouse gases
*5% reflected from land-sea surface
what contributes most strongly to the greenhouse effect in earth's atmosphere today?
If not for the greenhouse effect, Earth's average temperature today would be?
-18 deg C
how much of the water on earth is locked in ice caps and glaciers?
how much has sea level risen since the end of the last ice age?
climate and atmospheric composition
rock weathering can decrease C02 concentrations in air - links to mountain building
what are the effects of volcanic eruptions of dust on climate?
short term cooling due to solar reflection from volcanic dust
•Moraines contain glacial tills (unconsolidated)
•Tills become lithified to form Tillites
What is a rock called that forms from the lithification of glacial till?
zone of accumulation
The part of a glacial system where snow and ice are accumulating faster than they are melting away.
Zone of ablation
The lower part of the glacier, where more snow melts during the summer than accumulates during the winter
long, winding ridges of sediment deposited by meltwater streams that flowed in tunnels within, or under glaciers
a long, steep-sided glacial valley now filled by seawater
about how many ice age greenhouse cycles have occured over the last 2 million years?
about how long are the interglacial periods compared to the glacial periods?
10,000 yrs vs 100,000 yrs
properties measured in ice cores
properties measured of lake sediments
corals and tree rings
Chemistry, Growth rate
What was pennsylvania's climate like during the ordovician period?
hot and warm (like the gulf coast)
What are varves?
Alternating layers of silt or sand-rich and
clay-rich sediments in glacial lakes
Who is Milutin Milankovitch?
Was a Serbian scientist, he developed a hypothesis about Earth's long term climate changes
what climate state do most climate scientists think we are in now?
transitioning from icehouse to greenhouse
effects of global warming
-sea level rise due to glacial melting and water expansion
-agricultural productivity shifts
-changing weather patterns
-covers ~25% of earth's land surfaces
-primarily controlled by plate tectonics and climate change
-characterized by extreme dryness (hot or cold) and unique geologic processes
what is a desert?
land that is so extremely arid, that:
-evaporation prevents permanent surface surface water
-vegetation covers less than 15% of its surface
-annual rainfall to less than 10 inches
-deserts exist in both hot and cold climates
If Antarctica is a desert, why is there so much ice there?
the polar ice cap started forming millions of years ago
During the Holocene thermal maximum about 5000-6000 years ago, parts of the Arabian desert were?
wet, green, and fertile
low latitudes, low elevations, far from oceans
high latitudes, high elevations, near cold ocean currents
Five types of deserts
subtropical, rain-shadow, coastal,continental interiors, and polar
erosion by water and wind, weathering, soil formation, deposition
rare chemical weathering leaches ions, and evaporation salts both break and cement grains
-a dark surface coating of iron and manganese oxides
-native americans carved petrogylphs in a desert varnish
-forms v slowly from bacterial activity, dust, and water
-desert soils are thin, with poorly defined horizons
-they usually are colored like the bedrock nearby
-lack of roots magnifies sediment erosion and transport
-torrential rains generate dangerous flash floods
wind erosion and transport
-surface load: grains move in contact w land surface
-saltation: sand skips and bounces by grain impact
-suspended load: sediment carried in the air
-form desert pavement, a surface layer of stones
Why are the rocks of the Allegheny Plateau younger than the rocks of the Valley and Ridge?
the faulting and folding in the valley and ridge havre exposed those rocks to a higher level of weathering and erosion
-Continents aggregate to form single supercontinent
-Supercontinent separates to form smaller continents / Cycle Time: ~250 Ma
-rodinia 750 Ma
-Pannotia 570 Ma
oldest rocks, precambrian
late cambrian supercontinent
broad shallow seas resulting from the flooding of continents
the earth does not contain epeiric seas of the sort that existed 500 million years ago. why not?
so much ice is locked in continenta; glaciers todat that the sea level is lowertoday than 500 Ma ago
there were three mountain building episodes along the east coast of North America in the Paleozoic. What is the order of these orogenic events from oldest to youngest?
Taconic, Acadian, Alleghenian
Erosion of what mountain range and at what time in Earth history led to the formation of the organic-rich Marcellus Shale unit in Pennsylvania?
Acadian - Devonian
a foreland basin containing Paleozoic sedimentary rocks of Early Cambrian through Early Permian age.
what kind of faults characterize the valley and ridge province?
true or false: in the valley and ridge province, the ridges tend to be anticlinal structures and the valleys are synclinal structures
the position of continents in the future depends on:
-relative rates of plate subduction and divergence
-the emergence of new subduction zones and spreading centers
energy resources used up to 2010: what percentage was from organic matter?
how old is most of the world's coal?
which type of coal is the highest metamorphic grade?
ingredients for the conventional petroleum system
-source rock (organic rich)
-reservoir rock (porous and permeable)
-seal rock (impermeable) that helps to form
-a trap to contain the hydrocarbons
the Pennsylvanian oil boom
produced 50% of the world's oil up to 1901
producing hydrocarbons directly from the source rock
what kinds of natural gas production is old?
fracking and unconventional
what kinds of natural gas production is new?
horizontal drilling and fracking methods
in an unconventional oil and gas play
hydrocarbons are extracted from the reservoir rock and source rock
what is the most common mineral resource mined in happy valley today?
why are there so many old furnaces around happy valley?
to smelter iron ore
residual mineral deposits
formed from concentrating minerals from leaching of the soil
how much nonmetallic resources do industrialized countries use in one year?
-15,000 kg (15 tons) of resources per person
-US consumption comes to 4 billion tons of geologic material per year
Importance of groundwater
"Source of drinking water for 50% of US population Source of 40% of irrigation water Provides 25% of industry's water needs"
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