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381 Cards in this Set
- Front
- Back
- 3rd side (hint)
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__________ describes movements of Earth's crust through time. |
Tectonics |
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_____ Tectonics describes the movements of discrete segments of Earth's crust in relation to another. |
Plate |
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How did the huge continent break up? |
Cracks separated it into many many plates. Not just one plates moved. It moves like a relationship and interacts with plates |
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When did plate tectonics emerge? |
1960s |
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What are the two theories that plate tectonics is made up of, but not limited to? |
Continental Drift Theory Seafloor Spreading Theory |
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What is an early observation in the 19th century regarding plate tectonics? |
The coasts on the two sides of the Atlantic Ocean fit together like a separated jigsaw puzzle |
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Why did they not discover plate tectonics in the 19th century? |
They clung to the idea that large blocks of crust could not move over Earth's surface. |
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When did the land bridges idea come about? |
The 19th Century |
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What is one evidence of a land-bridge? |
Similarity of fauna between madagascar and india rather than Madagascar and South Africa |
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Where was the fossil Glossopteris (Permian Seed fern) found? |
Atlantic, South Africa, South America, India, and Australia |
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What did 19th century geologists hypothesize? |
Gondwanaland: landmasses connected by land bridges |
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Two examples of evidence for continental drift |
all the large continental areas were united as a single supercontinent, which Wegener called Pangaea Later Pangaea broke up by continents spreading over the ocean floor (hard to explain) |
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Who proposed continental drift in the 1910s? |
Alfred Wegener |
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Who further developed Continental Drift in the 1930s by providing new evidences? |
Alexander Du Toit |
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Three for Du Toit's evidence |
Fossil of a Mesosaurus along with others were found in South America and South Africa Stratigraphic sequence containing Mesosaurus and Glossopteris flora are similar among different continents Glacial deposits and movement |
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If you look at ________, glaciation makes more sense |
Pangaea |
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How did Du Toit know about the glaciers? |
Many glaciations deposited and could tell by age dating that they were all from the Permian |
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Two points about Continental Drift |
widely rejected for decades mainly by geologists of the Northern Hemisphere Dissatisfication - absence of mechanism |
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What was the weakness of the continental drift theory? |
We did not understand how and why the plates moved Focused on the southern hemisphere |
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Two points for Paleomagnetism Evidence in 1950s |
Earth's magnetic force lines intersect the surface of the earth at various angles Magnetized rocks record those magnetic angles |
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Two Paleomagnetism tests |
The continent was stationary and the pole had wandered over time The pole was stationary and the continent had moved over time |
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When did Harry Hess propose the seafloor spreading theory? |
1962 |
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Who was Harry Hess? |
Captain of a big ship during WW2 that had a sonar |
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Two evidences for seafloor spreading |
The central location of the mid-ocean ridge, with frequent volcanos Ocean basin not a permanent feature, apparent younger (based on amount of volcanic seamounts |
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What did Hess conclude? |
The entire crust has move. |
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Where is seafloor generated? Where does it disappear? |
Mid-Ocean Ridges Deep-Sea Trenches |
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What did Hess propose? |
Earth's semi-molten mantles is divided into thermal convective cells |
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Everything is driven by convective cells in the _____-____ mantle material |
slush-like |
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What provided definitive evidence for Plate Tectonics? |
Paleomagnetism |
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Two points for Vine and Matthews (1963) |
Found magnetic 'striping' along middle ocean ridge The striping patterns on the two sides of the ridge were mirror images of each other |
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Polarity changes... |
all the time |
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The relative width of those stripes are... |
proportional to the polarity intervals recorded by terrestrial rocks of known age. |
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When was new fossil evidence discovered? |
in 1969 |
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Where was the fossil Lystrosaurus (heavy-set herbivore in early Triassic) found? |
Antartica |
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Three points for Lystrosaurus |
Mammal-like reptile lived in marshes belong to therapsids Order similar fossil was found in India and South Africa decades ago |
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Antartica must have moved from... |
a warm equatorial region to a cold polar region |
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When did Pangaea start drifting? |
around the Triassic Peiod |
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A long time ago, the Pacific Ocean was... |
much bigger |
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How many plates are there? |
Eight large plates and several small ones |
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Plates move along their mutual boundaries, characterized by _____ |
faults |
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surfaces along which bodies or rock break from stress and move past each other |
faults |
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Three types of faults and what causes them? |
Normal faults (by tension Reverse of thrust faults (by pressure) transform or strike-slip faults |
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Four things that form at mid-ocean ridges |
lavas erupt through vents to form volcanoes pillow basalts form from quickly cooled lava underwater normal faults along the mid-ocean ridge transform fault offsets Mid Ocean ridge |
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example of a transform fault |
san Andreas fault |
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Four major features of mid-ocean ridge |
graben volcano earthquake pillow basalts |
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Lithosphere is sub ducted along... |
deep-sea trenches |
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Two points for lithosphere subducting |
slab of old oceanic lithosphere descends into the mantle volcanoes/earthquakes are associated (ring of fire) |
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Two points for volcanic arcs |
island arcs continental arcs |
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Major features of SZ (5) |
reverse faults trench forearc basin volcanic arc deformed belt |
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mainly metamorphosed sedimentary rock (called melange) |
deformed belt |
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Two ways to measure plate movements |
global positioning system hot spots |
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Mountain ranges change with... |
plate tectonics |
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What does MOR stand for? |
Mid-Ocean Ridges |
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Some hot spots happened... |
in the continents |
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Which plates are still suturing together? |
India and Eurasia |
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What can start the rifting of continents? |
Hot spots |
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Rifting also happens in... |
continental crusts |
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Hot spots give rise to three-armed rift, known as ______ ________ |
triple junctions |
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modern example of a triple junction |
afar triangle |
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What is the Afar triangle? |
East African Rift Valley + Red Sea + Gulf of Aden |
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Usually one arm of the triple-armed junction becomes a _______ ____ |
failed rift |
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When two continents rift, a valley can form and maker... |
a river when rain-water fills it |
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Not uncommon, all three arms of triple junctions... |
develop into segments of plate boundaries |
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Successful continents rifting produces... |
new sea, then new ocean |
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What happens with triple junctions? |
Rifting gets bigger and bigger and then turns into an ocean |
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Four steps to the atlantic ocean? |
begins with rift valley (Triassic period) valley opens up to the sea shallow seas form with narrow passive margin new ocean with wide passive margin
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East Coast: |
passive margins |
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West coast: |
active margins |
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High evaporation--> |
extensive evaporite deposit |
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Example of Embryonic stage |
East african rift valleys |
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Example of juvenile stage |
red sea |
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Example for mature stage |
atlantic ocean, arctic ocean |
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example for declining (getting smaller) |
pacific ocean |
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Example for terminal stage |
mediterranean sea |
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Example for suturing stage |
india-eurasia collision, himalayan mountains |
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Six stages of the Wilson Cycle |
embryonic juvenile mature declining terminal suturing |
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Motion of embryonic |
uplift |
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motion of juvenile |
divergence (spreading) |
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movement of mature |
Divergence (spreading |
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movement of declining |
convergence (subduction) |
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Movement of terminal |
Convergence, collision, and uplift |
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Movement of suturing |
Convergence and uplift |
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features of embryonic |
complex system of rift valleys and lakes on continent |
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features of juvenile |
narrow sea with matching coasts; oceanic ridge formed |
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Features of mature |
ocean basin with continental margins; ocean continues to rise at oceanic ridge |
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features for declining |
subduction begins, island arcs and trenches form around basin edge |
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features for terminal |
oceanic ridge subducted, narrow, irregular seas with young mountains |
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features for suturing |
mountains form as two continental crust masses collide, are compressed, and override |
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_______ is created by compressive forces. |
Folding |
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Most folds occur where ____ ______ _______. |
two plates converge |
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Folding thickens the crust and contribute to the growth of ________ _______ |
mountain chains |
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Mountain building always involves ____ __________ |
rock deformation |
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the process of mountain building |
orogeny |
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Example of continent collision mountain building |
himalayan mountain pyrenees mountain |
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Two points for himalayan mountains |
indian and euroasia plates are suturing together eventually the two plates are going to turn to one plate |
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One point for pyrenees mountain |
iberia sutured with France |
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When did the Pyrenees mountain happen? |
in the cretaceous |
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three points for pyrenees mountain |
natural border between france and spain started to form about 65 million years ago along sutured plated boundary, two plates are welded together |
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When are the dinosaur periods? |
cretaceous jurassic triassic |
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What is a second way mountains can form? |
orogeny along the subduction zone |
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Four subduction procedures |
accretionary wedge forearc basin volcanic arc foreland basin |
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What does a volcanic arc cause? |
crust warp downward forms |
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Foreland basin collects deep-sea sediments called ______, at the beginning; later on, choked by non-marine sediments, called _______ |
flysch molasse |
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Two subduction processes |
metamorphic belt fold-and-thrust belt |
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Metamorphic belt |
crust rocks are metamorphosed by heat along arc |
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fold and thrust belt |
those rocks are also deformed by compressive forces |
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Even if a mountain was leveled out over geologic time, ancient orogeny can be identified based on these features: |
horizontal: metamorphic belt; fold and thrust belt vertical: molasses overlying flysch overlying ancient rock |
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Two examples for mountain chain |
andes is associated with pacific "ring of fire" caused by Nazca sub ducts beneath S. American plate
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What is the largest mountain chain in the world |
Andes |
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Ten million years ago... |
inland sea occupied foreland basin |
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Interval of modern life |
cenozoic |
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interval of middle life |
mesozoic |
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interval of old life |
paleozoic |
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inconspicuous fossils |
precambrian |
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Are erosion and weathering the same thing?
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No
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Earth is a system =
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lithosphere + atmosphere + hydrosphere + biosphere
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earth is a _______ ______: only energy enters and leaves, no matter/elements do so.
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closed system
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What is the one thing getting in and out of the atmosphere?
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heat/energy from the sun
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What do matters within the earth system do?
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cycle between the lithosphere, atmosphere, hydrosphere, and biosphere
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Once in the Earth system...
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a particular element may exist in many different forms
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For most elements, they are ___________ in their total mass.
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conservative
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Elements exist in different ___________. The exchanges between these different ___________ are called _______.
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reservoirs
reservoirs fluxes |
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What is a chemical reservoir?
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a body of chemical entity that occupies a particular space
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Water reservoir:
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glacial ice
ocean rivers/lake groundwater |
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Chemicals _____ from reservoir to reservoir in _______.
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move
CYCLES |
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What is a chemical flux?
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the rate at which chemicals flow from one reservoir to another
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If flux in = flux out, the reservoir is...
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stable
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If flux in is not equal to flux out, reservoirs ______. Some will ______, while others _______.
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change
expand contract |
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Glacier will ______, while ocean will ______.
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expand
shrink |
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opposes the change
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negative feedback
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accelerates the change
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positive feedback
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Three examples of negative feedbacks of global warming
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plants proliferate in middle and high latitudes
carbon stored as plant biomass reduced CO2 in atmosphere |
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Three examples of positive feedbacks of global warming
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increased forest covering
lower albedo more heat absorption |
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Four major carbon and oxygen reservoirs
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rock and sediment
ocean and rocks biomass (plant and animals) Atmosphere |
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Where are more that 90% of oxygen silicates?
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rock and sediment
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Three important processes related to carbon and oxygen cycles in the Earth system:
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photosynthesis and respiration cycle
Rapid burial of carbon breaks the cycle Chemical weathering of rock |
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What happens if plants do more photosynthesis than respiration?
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Plant growth – net gain of biomass
carbon is temporarily sequestered in the biomass reservoir |
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Double the biomass only doubles the CO2 and O2 ____, not the ____________ _______.
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flux
reservoir volumes |
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Rapid burial of dead plants in swamps causes
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glaciation
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Carbon is removed from the photosynthesis–respiration cycle, so the ...
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atmospheric reservoir of C shrinks
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rapid burial of swamp plants
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carboniferous
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What happened in the carboniferous?
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glaciation and O2 rose to a very high level
coal & petroleum |
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respiration by bacteria is largely reduces; __ __ ____ _______ in atmospheric reservoir. |
O2 is more abundant
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atmospheric CO2 dissolves in water and becomes acid to erode rocks on land
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chemical weathering of rocks
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Where is much carbon stored?
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pelagic carbonate
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All of dissolved ions travel in river to the ocean, where calcium and bicarbonate recombine to form _________
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limestone
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Carbon dioxide is removed form the atmosphere by weathering, and stored in...
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marine carbon sediment
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Changes in ____ ____ _________ affect the atmospheric carbon reservoir
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rates of weathering
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Weathering rates are influenced by (4 things)
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mountain building
Precipitation vegetation temperatures |
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Four things that accelerate weathering
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large mountain range
higher precipitation acids secreted plant roots higher temperatures |
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How do we know that the atmospheric CO2 and O2 reservoirs (or concentrations) have changed over geologic time? How can we reconstruct the fluxes of chemical reservoirs?
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stable carbon and oxygen isotopes
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Two oxygen isotopes that reconstruct the ancient climate
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16O and 18O
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_____ is lighter and more abundant than ____
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16O
18O |
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Two carbon isotopes that study the chemical cycle
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12C and 13C
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____ is lighter and much more abundant that ___
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12C
13C |
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Plants preferentially use _______ carbon for photosynthesis
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lighter
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Whenever you see organic carbon, there is a...
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very high concentration of C12
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Which isotope do glaciers lock up? |
16O
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form from snow that precipitates from clouds, preferentially incorporate 16O
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glaciers
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More 18O concentrated in the ocean
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Glacier expanding
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Carbon 12...
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evaporates easily into the atmosphere
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Marin organisms incorporate the O isotopes into their shells, so changing the ratio of 18O in the fossilized shells indicates...
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changing global ice volume and temperatures through time
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Oxygen isotope ratios in marine animal skeletons reflect...
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ocean temperature
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Warmer temperature
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less 18O, lower 18O ratio in skeletons
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Colder temperature
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higher ratio of 18O into skeletons
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If you study a fossil oxygen ratio, you will know...
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what type of climate the fossil was from
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Carbon isotopes record the cycling of _______ ______
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organic carbon
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12C preferentially goes to...
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organic matters
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_____ _______ of organic carbon buries more 12C
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rapid burial
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If burial rate of carbon exceeds the weathering rate...
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heavier carbon is left in the atmosphere
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The ratio of C13 in limestone record changes...
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in rates of carbon burial
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extremely low C–13 content, much lower than that of organic matter
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Methane Hydrates |
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Earth's earliest time is referred to as the __________. |
Precambrian |
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How much of geologic time does the PreCambrian make up? |
90% |
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Less than 20% of rocks at Earth's _______ are of Precambrian age. |
surface |
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Hadean and Archean account for ___ of geologic time |
45% |
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Proterozoic accounts for ___ of geologic time |
45% |
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Precambrian is made up of: |
Hadean Archean Proterozoic |
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eon between the formation of the solar system and the formation of the first rocks on Earth |
hadean |
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Three key points about the hadean |
Earth acquired it's basic configuration (crust, mantle, and core) Earth underwent enormous physical changes (a very violent period named after Greek god of the underworld -Hades) Hot "rockless" eon
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Four steps for the origin of the solar system from a solar nebula |
spherical young nebula rotates slowly condenses, rotates faster, contracts to a disk rings of materials separated form the sun materials in the rings condenses to form planets |
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All planets including Earth formed within a... |
short period of time |
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Thanks to water erosion and tectonics on Earth, no rocks found are as old as Earth, so how do we date the origin? |
Meteorites Radiometric dating proxy for the age of planetary material in solar system, and therefore, approximate age of Earth Dating superficial moon rocks: 4.5 |
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Two reasons newborn Earth was very hot |
impacts from asteroids and meteorites strong radioactive decay Therefore: homogenous, molten Earth |
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Three points for "Differentiation by density then occurred" |
dense iron core dense silicates mantle less dense silicates float to the surface, termed a magma ocean eventually cooled to form oceanic crust |
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The moon formed from a... |
collision with a Mars-sized asteroid |
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What happened when an asteroid struck the Earth? |
the asteroid's iron core sank to join Earth's core The asteroid's mantle broke free to produce the moon |
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Two points for impacts on Earth |
intense heat melt newly formed Earth glancing blow knocked Earth into a faster rate of spin |
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Where did the atmosphere and ocean come from and how? |
from within, degassing from hot liquid Earth |
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Two points for degassing from hot liquid Earth |
gases escape from Earth's within to its surface steam escapes and condenses to water; some water also came from comets |
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Ocean salts mainly came from weathering of rocks later in the _______ |
archean |
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What did heavy bombardment do to the Earth? (2) |
melted Earth's crust and mantle repeatedly caused Earth and other planets to rotate on a titled axis |
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Two evidences of bombardment |
Moon's pockmarked appearance dating has shown those lunar craters are old |
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Seven keys to the Hadean |
origin of the solar system age of the Earth Origin of Earth's layers: magma ocean, solid iron core Early warm ocean atmosphere origin of the moon Late heavy bombardment |
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second oldest interval of geologic time |
archean |
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Three key points for the Archean |
substantial continental crust formed continental plates remained small because they were constantly rifting apart Earliest life |
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After 3.8 Ga, frequency of meteorite impact _________. |
declined |
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Earth in early Archean was still very ___. |
hot |
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Three points for the beginning of the Archean |
numerous hot spots plates were small, and are basaltic materials few continental crust at beginning of Archean |
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Two points of the origin of continental crust |
partial melting of Basaltic crust (from cooling down of magma ocean) forms felsic igneous rock (called granitoids) These felsic granitoids formed the nuclei of the first small continental crust |
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Early Archean, continents remained _____ |
small |
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numerous felsic bodies of rock |
protocontinents |
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protocontinents coalesced together (Late Archean) |
Microcontinents |
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an old and stable part of the continental lithosphere |
craton |
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craton exposed at Earth's surface |
shield |
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What is the largest craton? |
Canadian Shield |
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Two important rock types from the Archean |
Greenstone belts banded Iron formations |
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Three points for Greenstone belts |
high grade metamorphic rocks formation - protocontinent suturing along greenstone belt within archean and proterozoic cratons |
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Three points for Banded Iron Formations |
precipitated from oxygen consist of iron-oxide-rich layers alternate with chert The precipitation of iron does not occur in oceans today |
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silica was more concentrated in Archean ocean due to submarine volcanic eruptions |
chert |
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weathering; meteorites impact introduced more Fe to the ocean |
iron |
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Reason why Earth is special |
just the right size and temperature |
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Four reasons the earth is just the right size |
small enough not to attract meteorites small enough that the atmosphere isn't too dense big enough that the gravitational field holds its atmosphere/water temperature is right so that water is in liquid format |
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Other planets' problems |
venus is too hot mars has thin atmosphere, but too small to hold water jupiter is too cold and too violent |
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Earliest known fossil, produced by cyanobacteria |
stromatolites |
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Two evidences of life in the Archean |
stromatolites small carbon particles in Archean rocks |
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Isotopicall light carbon (C12) leads researchers to believe it must be from __________ by an unknown _______ _____ _____. |
photosynthesis primitive life form |
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Life first appeared on Earth ________ after 4.5 Ga |
sometime |
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Molds of individual _____________ cells found in Archean rock |
prokaryotic |
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had remained simple, inconspicuous, unicellular forms that in many ways resembled bacteria |
Archean Life |
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Eukaryotes do not appear in the fossil record until the _____________ ____. |
Proterozoic Eon |
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What is the Primordial Soup Theory? |
Life started in the ocean |
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What is the Panspermia Theory? |
Life started on Mars |
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Meteorites can bring in organic compounds, such as ______ _______ |
amino acids |
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The earliest life appears to be _____-______ and _________-_____ |
heat-lover oxygen-hater |
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Archean life _______ _______ in the vicinity of the Mid Ocean Ridge |
likely evolved |
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Archean life liked three things |
warm area anoxic environment abundance of required nutrients |
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Early Archean atmosphere did not have _________ present in large quantities |
oxygen |
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photosynthesis by cyanobacteria in ocean |
O2 source |
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oxidizing reduced iron and sulfur |
O2 sink |
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_____<____, so O2 failed to build up in the atmosphere |
Source < sink |
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What is the evidence of O2 failing to build up in the Archean? |
Banded Iron formations and pyrite in large amounts deposited in Archean rocks |
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___ is unstable under higher levels of Banded Iron Formations |
FeS2 |
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There is strong evidence of the buildup of oxygen in the atmosphere just after the ________- |
Archean |
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Four keys to Archean |
origin of continental crust some ancient crusts preserved in modern world archean atmosphere, very low O2 level Earliest life evolved near Mid-Ocean Ridges Prokaryote (such as bacteria), anaerobic |
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Continent plates in the Archean remained _____, ____, not ______ enough, different __________. |
small thin rigid composition |
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What is the earliest known fossil?
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Stromatolites
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Archean life had remained ______, _________, __________ forms that in many ways resemble ________.
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simple, inconspicuous, unicellular, bacteria
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What is a very important area and why?
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Austrlia because there are lots of animal fossils there.
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Four exciting events of the Proterozoic
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large rigid continents; first abundant fossils of living organisms; global glaciations; Oxygen build-up
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Two point for large rigid continents
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extensive deposition in shallow seas; modern tectonic, such as orogeny
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Point for oxygen built-up
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explosion of eukaryote including algae, first animal at the very end of the Eon!
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Many important things happened during the ______________.
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Proterozoic
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What formed during the Proterozoic?
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huge supercontinents (before Pangaea)
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What are the three eras that the Proterozoic is divided into?
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Paleoproterozoic; Mesoproterozoic; Neoproterozoic
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What dominated the ocean in the Proterozoic?
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Cyanobacteria (no grazers)
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What is one thing that happened during the Paleo-Mesozoic Era?
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The Great Oxidation Event (GOE)
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What happened climate-wise during the Neoproterozoic?
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Snowball Earth
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Cratons grew in size during the ___________.
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Proterozoic (Continental Accretion)
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What happens in continental accretion?
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Younger rocks become welded onto borders of pre-existing old rocks
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Two points for continental accretion
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sediment accretion; accretion through orogeny
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Shelf sediments compressed and metamorphose…
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thickens and hardens the crust
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Oldest well-displayed remains of a mountain system (thoroughly modern in character) formed 2 Ga
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Wopmay Orogen
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Any body of rocks formed by an orogeny
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orogeny
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From botton to top, what happens in rocks under an orogeny in the Paleo and Mesozoic
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Ancient Archean basement; succeeded by flysch (marine, such as shale); Give way to Molasse (nonmarine sediment)
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What is a perfect example of continental accretion?
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Assembly of North America
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Archean and Preoterozoic geologic provinces (or “Precambrian Cration”), preserved in ______ North America
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modern
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____________ is all the island masses.
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Gondwanaland
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Although now separated, ___________ was attached to ______ ________ during the entire Proterozoic Eon.
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Greenland
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________________ flourished in the oceans
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Cyanobacteria
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Where is the one place that Stromatolites are found now?
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West Australia
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Stramatolites are more abundant in the _______
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Archean
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What is the habitat or cyanobacteria?
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shallow marine and continental shelves, so their proliferation resulted in part from an increase in the size of continents, also from lack of grazers
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In the Paleo and Mesoproterozoic, cyanobacteria…
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reached gretest diversity
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In the paleo and meso Proterozoic… |
single plantlike protists that can do photosynthesis joined cyanobacteria |
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Two points for single celled plantlike protists
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they are eukaryotic fossil; earliest conspicuous eukaryotic fossil
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acritarchs
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Any small organic structure that cannot be accounted for is classified as this
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acritarchs |
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Prokaryotes are still __________
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dominant
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Probably the first eukaryote fossils
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acritarchs
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In the paleo and meso Proterozoic…
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multicellular plantlike protists likely arose soon |
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2 Ga ago in early Proterozoic Eon, Prokaryotes, including cyanobacteria, _________ the ancient ocean; and earliest Eukaryotic algae (acritarchs and others) joined them
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dominated
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Photosynthesis by all of these groups released LARGE amounts of ______ into atmosphere.
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oxygen
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In the meso and paleoproterozoic,, the Earth system shift from ___________ to _________.
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anaerobic; aerobic |
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What happened during the Great Oxidation Event? |
dramatic increase of O2 in the atmosphere |
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Why did oxygen start to build up?
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because of huge burial
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Four evidences of Great Oxidation Event
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banded iron formation were rare; redbeds became abundant; pyrites were rare in sandstone after 2.3 Ga; opposite of evidence of low oxygen in the Archean |
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Why did oxygen start to build up?
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Cyanobacteria started to do photosynthesis 3.5 billion years ago.
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What happened during the Great Oxidation event with the rocks?
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Banded Iron Formation stopped, instead , redbeds (highly oxidized iron rich sediments showed up)
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Why was there a buildup of atmospheric oxygen?
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BIF’s were a huge sink for O2, used us oxygen as fast as it appeared, as did respiration; Photosynethesis by both prokaryotes and eukaryotes (cyanobacteria, acritarchs) released large amounts of oxygen
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At this point, the ______ is significantly bigger than the ____.
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source and sink
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Two things that the Oxygen build-up likely triggered
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first glaciation; diversification of eukaryotes
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How did Oxygen build-up?
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A warm, methane-rich atmosphere affected the rising of CO2
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CH4 is a ____ _________ greenhouse gas than CO2. Rising O2 oxidized CH4, resulting in a __________ greenhouse effect.
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more effective; decreasing
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Atmosphere cannot…
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hold as much heat as before
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Methane is…
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short-lived
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Two evidences of Huronian glaciation
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evidence in southern Canada, north of Lake Huron Varves deposits (proglacial lake); some with dropstone; Tillites found elsewhere globally
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With continued continental accretion…
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supercontinent formed.
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Three supercontinents formed and broke apart during the Proterozoic econ, and _______ and _________ are two of them.
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Rodinia and Pannotia
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How many orogenies happened in the Neoproterozoic?
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3 |
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Three points about the neoproterozoic
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began to form in Neoproterozoic; fully assembled about 900 Ma; began to break apart about 700 Ma
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One point for Rodinia beginning to form
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Grenville Orogeny along eastern NA
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Two points for Rodinia fully assembled
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laurentia united with other land masses; centered around the equator
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Following the break-up of Rodinia, several landmasses merged to form the supercontinent of _________.
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Pannotia
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When did Pannotia form?
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600 Ma
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When did Pannotia break up?
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550 Ma
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Pannotia split into _________, ________, and ________, with the main landmass, ___________, south of it.
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Laurentia, Siberia and Baltica; Gondwanaland
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How many continent masses combined to form Pannotia?
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Five
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Western border of Laurentia remained…
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a passive margin from then on
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Rifting area would expand to become…
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the Pacific Ocean
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When Pangaea rifted, that is how…
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we ended up wiith the continents where they are today
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What happened with Fauna during the Neoproterozoic?
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Animals burst onto the scene
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Animals probably got bigger because of…
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high oxygen level
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First five earliest animal fossils
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very small animals and embryonic embryos; frond-like ediacaran forms; simple horizontal burrows; small skeletonized animals
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The oldest animal-like single-celled organism…
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closely resemble certain amoeba like organisms of the modern world
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Oldest multi-celled animal organisms…
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resemble bilaterally symmetrical animals of the modern world and were more advanced than sponge and cnidarian
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Evolutionary radiation of animal life occurred during the final 30 Ma of the ______________ ____.
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Proterozoic animal
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Oldest known undoubted adult animals preserved in the fossil record
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ediacara fauna
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Three points for ediacara fauna
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discovered in Australia, but have since been found all over the world; soft-bodied animals; some are similar to modern forms.
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In the Cambrian, all the phylums…
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show up
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Ediacara fauna suggests…
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the origin of major animal groups
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Animals began ____________ dramatically since 570 Ma
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diversifying
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Two points for other trace and skeleton fossils
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evidence of worm-like creatures; skeletal animals.
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Skeletal animals…
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appeared near the very end of the Proterozoic
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Were the burrows in the neoproterozoic complex?
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No
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How many periods are in the Paleozoic era?
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6
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Two things that the Paleozoic era starts with
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animal explosion; one supercontinent breakup
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Two things that the Paleozoic era ends with
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ends with the largest mass extinction; ends with the formation of another supercontinent
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Three Mass extinction divide the Palozoic era into three segments |
early Paleozoic, middle Paleozoic, late Paleozoic |
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During the early Paleozoic, most animal…
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phyla of the modern world appeared.
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Two points for the Cambrian
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global transgression; rapid diversification of life in the ocean, “Cambrian explosion”
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Three points for Ordovician
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period of sustained higher sea level; Ordovician radiation; glaciation-related global mass extinction
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Five points for Trilobites
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arthropods; first appeared in the early Cambrian; segmented exoskeleton; deposit feeders (extracting organic matter form ingested sediment); have eyes, teeth
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Early Cambrian groups evolved…
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skeletons
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Constitute the oldest diverse skeletonized fauna on Earth; small shelly animals
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tommotian fauna
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Mos of the tommotian fauna
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cannot be assigned to a living phylum
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Three main things that came about in the Cambrian
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trilobites; older reef builder; conodont
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Three points for achaeocyathids
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apparently sponge; suspension feeders; only showed up in the early Cambrian
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Even the first ___________ showed up.
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vetebrates
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Extinct, resembling eels, jawless
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conodont
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Two points for Cambrian Explosion
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happened in Early Cambrian; appearance and rapid diversification of most major phyla
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What are later Cambrian fauna represented by and what are they mainly?
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Burgess Shale Fauna, arthropod and worms
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Two points for Mass Extinctions in the Cambrian
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trilobites were struck the most; each mass extinction was followed by the re-diversifcation of trilobites.
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The last major extinction defines the _________-__________ boundary. Reasons of this ME are ___ ______ _____.
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Cambrian-Ordovician; not well known
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Why suddenly all the skeletons so abruptly? (2)
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Change in ocean chemistry; appearance of advanced predators (the loss of “innocence”)
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Three early Ordovician animals
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Trolobites remained abundant, but not dominant; nautoloids (cephalopod class of mollusk); Graptolites (extreme marine plankton)
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In the middle-late Ordovician, the most dramatic _____________ _________ of marine life, with _________ increase the animal density.
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Evolutionary radiation; threefold
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Where was the burrowing bivalve?
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in the sediment
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Where was the snail, brachiopod, crinoid, new reef builders?
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on the sea floor
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What was the nautiloid?
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Pelagic life
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Two reef builders
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coral; stromatoporoids (sponges)
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Together, coral and stomatoporoids formed massive _____-______ ______ throughout middle Paleozoic time.
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cora-strome reefs
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Two types of coral
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tabulate coral and rugosa coral
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Ordovician is best known for…
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its diverse marine invertebrates (about 1300 genera recognized in Upper Ordovician rocks.
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Mass Extinction, however…
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sets back marine diversification.
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What percentage of all genera of marine animals died out during the Ordovician mass extinction and why?
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about 50%; Glaciation
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Less abundant with restricted occurrence in Cambrian; and rare in Ordovician
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stromatolites
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Why were stromatolites rare in the Ordovician?
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due to pressure from grazing animals
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We know _______ about life on land during the Cambrian and Ordovician.
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nothing
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Near the beginning of Cambrian, __________ broke apart (recall that _________ was located near the _________)
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Pannotia; Pannotia; Equator
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Neoproterozoic cratons…
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continued rifting during Cambrian
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Four major Cambrian cratons
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laurentia; Siberia; Baltic; Gondwanaland
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Laurentia straddled…
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the equator
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Laurentia was turned…
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clockwise nearly 90* from it’s modern orientation
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Baltic moved…
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southward
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Gondwanaland was stretched from…
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the equator to the South Pole
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The Cambrian Period was notable…
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for the progressive flooding of continents
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Shoreline moves landward, resulted from sea-level rise
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transgression
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What was the cause of transgression in the Cambrian
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retreat of Proterozoic ice + continental rifting
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The transgression event opened up new…
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habitats where marine invertebrates radiated and flourished
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The early Paleozoic transgression is one of…
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the largest and most persistent sea-level rises of the entire Phanerozoic Eon
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What is a typical Cambrian transgression sequence along the Grand Canyon?
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Vishnu Schist; Tapeats Sandstone; Bright Angel Shale; Muav Limestone; Dolomite
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In the Ordovician, Baltica…
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migrated northward into the tropics, where tropical limestone accumulated
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In thr Ordovician, Gondwanaland…
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encroached on the South Pole.
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There was _____ glacier growth at the end of the Ordovician
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large
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What caused the large glacier growth?
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global cooling, causing sea-level to drop
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The Taconic orogeny raised…
|
mountains in eastern Laurentia
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Two points for the Taconic orogeny
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Taconic island arc broke free from Gondwanaland early; The island arc moved northward toward Laurentia, and collided with east Laurentia during Ordovician
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Taconic orogeny affected most of modern-day New England, and is the _____ of _____ _________ in the formation of Appalachian mountain belt.
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first of three orogeny
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In the late Orovician….
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major ice sheets expanded on Gondwanaland at the south pold.
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There is glacial evidences…
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at polar location centering Paleo Africa.
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How long was the Late Ordovician Glaciation?
|
short duration, about half a million years
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Shifts in carbon isotopes indicate ______ of organic carbon (isotopically light)
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burial
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Less carbon deposition →
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less CO2, back to atmosphere
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If carbon shifted to a positive value…
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organic matter burial occurred
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Oxygen shifted to positive values…
|
it was colder
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Late Ordovician Climate caused…
|
mass extinction (50% of marine genera)
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What were the two pulses of the Late Ordovician mass extinction?
|
global climate cooling (onset of glaciation); global climate warming
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Two points for global climate cooling
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cooling at equator eliminated tropical taxa; global regression
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One point for global climate warming
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warming eliminated cold-adapted taxa that had shifted their habitats to lower latitudes
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Seven points for Cambrian
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Starts with an “explosion” in the sea; most invertebrate phyla appear; animal skeletons rose; trilobites dominate; continents were dispersed; persistent transgression; trilobite extinction marks end
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Four points for Ordovician
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great diversification of invertebrate fauna (proliferation of corals); Baltica in the tropics; Gondwanaland encroached on the south pole; Taconic orogeny; glaciation causes mass extinction and SL drop |
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