How do compositional differences between oceanic and continental crust affect Earth's topography?
Well the oceanic crust is composed mainly of Basalt, which is thinner than continental granite but denser. Continental crusts granite is thicker but less dense.
The process of sea floor spreading?
Well, molten rock is pushed up to the surface where it cools to form hot, buoyant rock. This then pushes the existing rock near the vent away keeping the new rock closest to the vent. spreading the sea floor.
At what type of plate boundaries would you expect to find crust formation? what about destruction?
Divergence creates new crust (underwater volcanoes) Convergence is possibly due to the fact that it melts rock and convergence is when one shelf sinks under the other into the mantle.
How can plate tectonic motion affect ocean circulation and climate?
Plate tectonic motion can affect ocean circulation by affecting the distribution of warm and cold currents, such as in the Gulf Stream.
How does sea floor spreading rates affect global sea level?
If the sea floor spreading is fast then the water level stays relatively even. More young hot crust. If the sea floor spreading is slow, it creates an overall low basin and lower sea level.
How can changing sea levels affect biotic interaction? Biotic isolation?
The sea level can affect where there is more primary productivity. It can isolate movement for organisms and isolate environments.
Why are continental shelves important to biotic ecosystems?
control primary productivity of an area as well as restrict environments. Affects wether its a deep or shallow drop off, how much land there is. Continents diverge flow of warm and cold currents so also the temperature.
Why is the Stratigraphic record important?
The stratigraphic record contains chemical and physical info on past environments. The stratigraphic record contains biologic info on past environments. And the stratigraphic record contains info on changes in surface of earth overtime.
What are the basic stratigraphic principles and how do they help us interpret history?
The principle of Original Horizontality-sediments tend to be deposited in a continuous flat layer like horizontalness. The principle of Lateral Continuity- take sediments from the river and push to sea, they tend to stay against the delta but otherwise spread out. The principle of Superposition- Younger sediment is deposited on top of older sediment Bioology changes through time!
What do unconformities represent? What influence do they have on stratigraphic interpretation?
There are uncertainties with unconformities. They are able to influence the ability to accurately gauge the age of a fossil.
Whats the difference between body fossils, trace fossils, and chemical fossils?
Body fossils- skeletal components with/wo soft parts. Trace fossils- preserved elements that show or record organisms activities, but no trace of the organism. Chemical fossils- like having a carbon isotope signature in a rock.
How might feeding trace fossils differ in regions of abundant food and scarce food?abundant oxygen?
If there was an abundance of food the trace fossils would be random, everywhere. If there was scarce food, the trace fossils would be more methodic incertain locations. abundant oxygen would have lots of movement signs in geo record scarce oxygen=less signs of movement or none at all
How might you interpret an abundance of fossils in an area but minimal variety in terms of ancient climate?
That one species obviously thrived in that area which could have been inhospitable to most.
What were the Archbishops, Jolys, and Kelvins assumptions for the age of the earth?
They assumed there was deposition, geologic tilting of the strata, erosion, and superposition of rock on top of each other.
Whats the difference between absolute and relative age dating?
Absolute Age Dating is a precise numerical date, directly measurable in lab. Relative Age Dating uses sequential relationships to assume an order of evens.
What is Radiometric dating? sources of error?
Radiometric dating occurs when the parent isotope decays to the daughter isotope at a constant rate. Using half life and amount of parent and daughter, you can mathematically define age. error= parent and daughter mix ups, like some minerals have both or some allow parent or daughter to be added or taken through time
Why is Zircon a good mineral to date radioactive decay?
Zircon is an igneous mineral from volcanic events.
Superposition and Cross Cutting
Superposition= younger rock on top of older rock Cross cutting= Intrusion will be younger than rock it intrudes upon Date intrusion to find youngest age for rock Date rocks to find oldest age for intrusion
C isotope stratigraphy
easy to measure need limestone though dentridal zircons are only in sandstone C isotopes changes occur over long and short timeframes
Biostratigraphy to find successions
Deposition rates and resolution- the higher the deposition, the better the fossil preserves and the better the resolution is BUT not all fossils of organisms can be used for biostratigraphy
What characterisctics are good for usuing a fossil for biostratigraphic anaylsis?
An abundance of this fossil in the geological record Morphologically distinct geologically distinct around the world an organism that can live in many environments aka widespread
Wide geographic extent and Broad environmental tolerance
an organism that displays these is called a cosmopolitan organism!
Pores within the original structure filled with minerals that precipitate form solution...Silica
The substitution of one mineral with another on the fossil Calcite in shell replaced by Pyrite
Original organism is burned up (intense heat) so all that is left is a carbon "footprint"
What conditions favor preservation of organisms as fossils?
1. An organism must be abundant in its environment. 2. The existence of hard parts. 3. Rapid burial. 4. Low oxygen conditions.
3 examples of evolution?
Bat arm versus human arm Embryonic change Darwins Finchs
What is Darwin's hypothesis of evolution by natural selection? Why is sexual recombination of genes important?
Organism population shows variation. Variation is heritable. Some traits are more favorable than others for survival. Surviving organisms reproduce and may pass favorable traits down. Through time favorable trait frequency rises. Sexual recombination is important because it is the source of variation within populations.
Why might radiation of a new species occur after an extinction?
because new species could have been hunted by the now extinct organism. So new species is unrestricted and thrives.
How does convergent evolution of animal forms support evolution by natural selection?
Because animals all have same basic forms, but they have adapted them to their different environments.convergent evolution= animals with same basic forms in different areas, like tiger and lion.
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