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104 exam 2
Terms in this set (80)
how do stomata correlate to the amount of CO2 in the atmosphere
more holes, less CO2
less holes, more CO2
how do the two oxygen isotopes work?
the O16 will evaporate and O18 will stay in the water
when its warmer ->melts back into ocean O16 will be in shells
when its colder-> stays as glaziers and O18 makes shells
What is fractionation?
bias for or against one isotope or another
how can glacier ice cores help us see history?
ice cores record climate history in oxygen isotopes and trapped bubbles of air with CO2
explain carbon isotopes
12C is incorporated into living tissue during photosynthesis
What was the hadean eon like
surface was a magma ocean
was heated by impacts, decay of short half-life isotopes
formation of crust
oldest minerals are dated to be 4.4 billion years old, suggest crust; rocks even that early
what is a greenstone belt?
surface rocks (sediments and volcanics) of granite and gneiss that are continental crustal rock
where is a local spot where some of the oldest rocks can be found?
what is the origin of the oceans?
comets and volcanic degassing
What was the early atmosphere like?
CO2 methane water, ammonia
how was the first oxygen produced?
CO2 + H2O -> O2 and sugar
What is life?
replication, metabolism, and evolution-> mutation/natural selection
What is abiogenesis?
synthesis of living things from inert matter in the environment
what is panspermia
the "cosmic seed"
What is the Miller-Urey experiment?
this experiment demonstrates that organic compounds could be made by stimulating conditions on early Earth
what was the most primitive life on Earth?
archaebacteria; survived extreme conditions, deep sea vents, methane seeps
What is our chemical evidence for life?
carbon isotopes suggest fractionations by photosynthesis by 3.85 billion years ago
what is our sedimentary evidence for life?
stromatolites by 3.5 billions years ago
what is our body fossils evidence for life?
preserved cells 3.5 billion years
What are BIFs?
iron bearing sediments that mark the transition to an oxidized world 2.5 billion years ago
What was the Archean Atmosphere like?
no oxygen, pyrite sand grains to prove it
When was the first endosymbiosis happening?
2 billion years ago
How do continents grow?
accretion at margins and deposition on the platform
When do we get the normal plate tectonics?
What is the Wilson cycle?
The cyclical opening and closing of ocean basins caused by movement of the Earth's plates.
What is Snowball Earth?
tropical carbonate rocks overlain by glacial till; suggesting global glaciation
What is albedo?
reflectivity of earth surface materials to sun's radiation
How to get into a snowball earth?
low solar luminosity
continents at low latitudes increase albedo
weathering pull down CO2
How to get out of a snowball earth?
volcanism releases CO2, builds up in the atmosphere to super greenhouse conditions
snowball Earth events near the Proterozoic
there were three events that happened at the end of the Proterozoic
What are the first multicellular organisms?
ediacaran; large soft bodied fossils of unclear affinity
what is the boundary between the precambrian and Cambrian?
540 millions years ago
Why is the Cambrian period called an explosion?
members of all major animal phyla appear in short amount of time
why is the Burgess Shale so important?
because it has amazing lagerstatte; soft-bodied preservation reveals initial diversity of life after the explosion
What is an arthropod?
segmented body, jointed legs, exoskeleton
what is the cone of increasing diversity?
slow accumulation of diversity
what is decimation and diversification?
rapid explosion of diversity, subsequent diversification of those that survive to become modern phyla
what is diversity vs. disparity
# of species vs. # of functional body parts
what was the Cambria's diversity v. disparity
low diversity, high disparity
what is a sloss megasequence?
large-scale cycles in sea level caused in part by changes in sea floor spreading rates and changes in volume of mid-ocean ridges
What is a transgressive sequence from the Paleozoic?
the Sauk sequence
what is a regressive sequence from the Paleozoic?
What happens when continents flood?
epimeric seas, great American carbonate bank, oolites, evaporites
when do fish diversify?
lobe finned fish transition toward amphibians
when were the first forests formed?
Giboa forest in NY
what events formed the Appalachians
tactic, acadian, and allegheny orogenies
what is the Appalachian basin?
a foreland basin
what is the Mississippian known for?
widespread limestones and crinoids
what is the Pennsylvanian known for?
coal swamps, trees, ferns, lycopods
what does the burial of organic matter cause?
raises atmospheric O2, makes big bugs, forest fires
what is a synapsid?
mammal like reptiles; our ancestors
what happened at the end of the permian?
the biggest mass extinction
What causes the extinction?
the formation of Pangea
sea level fell; less coastlines
What are the Mesozoic periods?
Triassic, Jurassic, Cretaceous
245 million to 66.4 million
what caused the extinction?
formation of Pangaea
* sea level fall, less coastline
*siberian traps, release of CO2
What was the mesozoic life like?
"age of the dinosaurs"
rifting of Pangaea
mesozoic marine revolution
rocky mountains form
bounded by mass extinctions
what happened the ammonites?
their sutures get more complex
What are the continents like during the mesozoic?
rifting begins to break up Pangaea and open the Atlantic
by the late cretaceous - continents are almost in current day position - many eperic seas
what is the Wilson cycle
continents rift apart, spreads and then comes back together creating an orogeny
what are some marine reptiles?
mosasaurs, plesiosaurs, ichthyosaurs
what is a normal fault?
extension, headwall moves down
what is a reverse fault?
compression, headwall moves up
what is the mesozoic marine revolution?
more predators, escalation, arms race
triggered by by more food and nutrients
what are the plants of the mesozoic?
cycads, conifers, ferns
How was the extinction at the end of the mesozoic caused?
impact of asteroid
iridium, shocked quartz, tektites, crater
what is the Deccan trap?
more than 500,000 cubic km of basaltic lava released over 5 million years
what is a Bucky ball?
carbon cages that contain a He trapped in the lattice
what survived the KT extinction and how?
small carnivorous Dinos and tiny little rats
survived by not eating a lot, having a slow metabolism, and a small body size
what three orogenies that created the rockies
what was the Paleocene like?
warm, wet, palms in Alaska and forests and crocs in the arctic
HIGH CO2 levels
what is the PETM
Paleocene-Eocene Thermal Maximum
methane releases from ocean sediments, super greenhouse, carbon isotope excursion
what happens after the PETM?
it cools down a lot!!
What happens in the Oligocene?
due to cooling climate from drop in greenhouse gases
What caused the amount of CO2 to decrease?
increase of chemical weathering of feldspars creating SiO2 and clay
furthermore, Antarctica being isolated, current started to cause ice growth
what was North America like during the oligocene?
When did North America get ice?
3 miles thick of ice
what is the milankovitch theory?
glacial-interglacial climate cycles are driven by changes in earth's orbit as it spins on its axis and revolves around the sun
is there any evidence to prove the milankovitch theory?
yes, oxygen isotopes show the growth and decay
what are some of the consequences of glaciation?
sea level was lower
isostatic depression follow by rebound
erosion, creating finger lakes, smoothed topo
deposited sediments and drumlins
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