exam 1 Flashcards
curvature of earth
Affects intensity of light hitting the planned at any one point
causes light distribution, Coriolis, increased variations in photoperiod with higher latitudes, wind patterns
Orbit
Small changes over time (e.g. wobbling) causes changes in solar insolation (radiation that impacts climate change)
causes light distribution, Coriolis, increased variations in photoperiod with higher latitudes, wind patterns
Tilt
Causes seasonal changes
causes light distribution, Coriolis, increased variations in photoperiod with higher latitudes, wind patterns
albedo
reflexivity of earths surface, part of why Antartica is so cold
Total reflectivity: albedo =1
solstices
Solstices occur in June & December, edge of circle of illumination is around 66.33º causing polar circles to be 24 hr sunlight or darkness, depending on earth’s position in orbit; opposing seasons in northern vs southern hemispheres
equinoxes
Equinoxes occur in March & September, edge of circle of illumination passes directly through the poles, daylength = nightlength everywhere on the planet for that one day
solar & infrared radiation
Some solar radiation is lost or reflected back to space from earth’s surface. Some is absorbed at surface, radiated back to atmosphere as infrared radiation (IR)
Greenhouse gases (CO2, CH4, O3) trap IR, warming the planet (necessary for life)
North Pole vs south pole
receive the same amount of solar radiation just at different times of year
temp of North Pole (arctic)
-why
-18 C bc of oceans breaking up arctic sea ice in the summer
Antarctic (South Pole) normal temp
-why
-52 C bc its a continent with ice sheets (high albedo) and high elevation (4000+ m)
Antarctic ice & precip
<2% ice-free lan, 2-4 km thick ice sheets, interior of the continents gets <2” of precipitation (cold-desert)
-little snow that falls on cold desert doesn’t melt and accumulates over time
Antartica plants and animals
only two flowering plants and only on the antarctic Peninsula, no fully terrestrial vertebrates (only few inverts)
why study Antartica?
1) Helps understand the fossil record, paleobiogeography, plate tectonics
2) Development of Earth’s climate (past & present)
3) Last relatively pristine place on Earth
4) Evolution of species in extreme conditions
5) Human presence is growing, future resource interest
6) Vital for climate change & sea level rise information (now & future - 70% of Earth’s freshwater is trapped in ice)
7) Fascinates imagination due to its extreme condition and remote location
plate tectonics
Plates on the planet move independently of each other, due to the movement of the asthenosphere under the lithosphere
Rodinia
supercontinent that formed 750 mya, SWEAT hypothesis suggests it once included western NA and east Antarctica by granites
gondwana
southern supercontinent (warming period cause oceans to become very acidic possibly causing marine loss, lots of vegetation) 550 mya
pangea
supercontinent that formed from the northern and southern continents, carboniferous ice sheet 300 mya
radioactive isotopes
change atomic # and mass at a constant decay rate
stable isotopes
remain stable with fixed number of protons of the same element, but each isotope has different number of neutrons and mass.
-stable oxygen isotopes are extremely useful in determining past temperatures
igneous
from liquid magma to solid rock as they cool
-basalt, granite
sedimentary
accumulation of pieces of other rocks that fuse together, can see layers, impressions, fossils
-sand stone, siltstone, limestone)
metamorphic
changed rock from melting/pressure
-schist marble
continental crust
less dense but thicker
-up to 35 km thick
made of granite
oceanic crust
denser but thinner -6km made of basalt
lithosphere
solid but elastic, broken up into plates, including the continents, and move about asthenosphere
asthenosphere
liquid magma layers that causes plate movement
-hot spots can break through lithosphere creating island chains
divergent boundaries
spreading plates away from each other (most underwater),
-forms new continental crust as they spread
caused by mantle convection
convergent boundaries
colliding plates, one subducts or goes under the other, can cause uplift
-form mountain ranges/earthquakes
cause day mantle convection
transform
plate edges grinding past each the run opposite directions
caused by mantle convection
rifting
lithosphere stretches causing the continental crust too thin. Asthenosphere rises
-Volcanoes/fault escarpments
SWEAT hypothesis
Southwest - East Antarctica connection. When Rodinia was a supercontinent eastern Antarctica and western North America were connected. Based on isotopic geochemistry of equivalent granite found in both places. The isotopic composition developed when the rock formed.
glossopteris
fern-tree, fossil leaf impressions in sedimentary rock from Mt. Wild on Antarctica (255 mya). Also found in India, Australia, South Africa and South America
-evidence for continents once being connected, supporting plate tectonics
lystrosaurus
therapsid dicynodont reptile that survived mass extinctions found in Africa, Antarctica, European Russia & Mongolia by Edwin Colbert
-evidence for continents once being connected, supporting plate tectonics
thrinaxodon
cynodont therapsid found in Antarctica and Africa
-evidence for continents once being connected, supporting plate tectonics
when did Gondwana break up
started 180 mya finally Antartica split 32 mya when the South Antartica Peninsula
impact of gondwana
drakes passage and forming the circumpolar current which initiated cooling (ice started to form) and isolation of the Antarctic continent
jurassic period dinosaur fossils found on antartica
180 mya
cryolophosaurs, long-necked sauropods, mosasaurs, plesiosaurs, etc).
what caused the breakup of Gondwana
mantle blumes
antarctic circumpolar current
only current that flow around the globe in southern hemisphere
-helps isolate antartica
microplates
Tectonic plates too small to track, positioned themselves as part of Antarctica such that the Ellsworth Mountains w/ anomalous orientation when Gondwana broke up
transantarctic mountains
(divides east & west Antarctica), and they sit on a plate boundary.
-above sea level
Ellsworth mountains
sit on a micro pate
when did the ice sheet start, and reach, thickness
started 32 mya
-sediment cores at Prydz Bay have glacial boulders and pebbles carried by glaciers and deposited in bay by then.
Reach current size/dimensions by 14 mya
ice sheets thickness and area
4km thick and cover 14 million km^2
how does the weight of the ice sheet affect the continenet
pushes it down but when glaciers melt isostatic uplift occurs
-evidence in raised beaches, former beaches w/ water-worn cobble/pebbles
how much of earths freshwater is in antarctic ice sheet
60-80%
how high would sea level rice if antarctic ice sheet melted
60-70 m
what does antarctic ice sheet sit under
burried mountain ranges
west antarctic ice shet rests on rock below sea level
cryolophosaurus
“forzen crusted Dino”
proved antarctic was a forestproof of Gondwana that Ned Colbert found in the 1960’s
when did penguins evolve
61 mya
dry valleys
ice free sedimentary rock place
-lots of paleontology done there
crevasses
as glaciers melt more heat is absorbed which can open crevasses
-very dangerous and difficult to see and navigate
moraines
blodzoed dirt
lateral: on the outsides
medial: in the middle where two come together
terminal: at the bottom where they’ve converged and where they’re pushing dirt in front of them
glacial stratiations
as a glacier moves over rock below it will smooth and polish them. leaves akas in the rock indicating direction of glacial flow
glacial erratics
rocks that fall onto a glacier and become deposited in an entirely new area when the glacier melts
-coloration and type of rock often doesn’t match the geology in the new area causing them to stand out
ice regulation
when the bottom of a glacial melts under pressure, and refreezes when the pressure is relieved
dialectic sediment
poorly sorted sediments with particles ranging from clay size to boulders.
ice rafted debris
dirt and rock trapped in a glacier that gets carried to sea and then melts, depositing the debris into the marine sediments