plate tectonics Flashcards
What was Wegner’s theory and why was it rejected/accepted?
Wegner presented the theory of Pangea and the separation of continents through continental drift. Initially it was not accepted because he did not present any mechanism for the plate movement, but as plate tectonic movement was better studied it was more widely accepted.
what is seafloor spreading and what are the lines of evidence?
seafloor spreading is the separation of tectonic plates in the ocean as hot material rises and forces them apart. seafloor spreading is evidenced by lines in the mid-oceanic ridge that alternate in polarity, indicating new spreading.
how can we use seismology to learn about the internal structure of the Earth?
By studying seismic waves we can understand how the core of the earth is structured. P & S waves have different properties, and because s-waves cannot go through liquids we can find the boundaries of the outer core, and better understand the inner core.
what is the internal structure of the Earth and its characteristics?
crust - thinnest layer riding on top, sensitive to seismic changes
mantle - made up of the lithosphere (“rigid crust”) which is cool, strong, and brittle, and the athenosphere which is hot, slow-flowing, and “plastic”
outer core - very hot liquid
inner core - hot and dense solid mass
what are the basic types of plate boundaries?
divergent - plates moving away
convergent - plates moving towards each other
transform - plates moving past each other
what is isostasy and how does it relate to mountain building?
Isostasy is the concept of equillibrium on the crust, which is carried out by having the less dense crust being higher up than the more dense parts. Isostasy on the crust is evidenced in mountains, as it causes uplift.
Isostatic uplift in mountains occurs as a result of erosion. As more of the moutain is eroded due to rain and other natural processes, isostasy will cause the mountain to “grow” in order to maitain equillibrium and replace the density lost.
what are magnetic stripes and what do they mean?
the alternating stripes in the mid-atlantic oceanic ridge indicate changes in polarity, and are evidence of seafloor spreading
subduciton zones
Convergence of tectonic plates where one plate dives beneath another and is consumed in the mantle
the oceanic is always the plate that subducts when converging with continental plates
mid-oceanic ridges
A topography high commonly found in the central part of oceans characterized by seafloor spreading.
ex. Mid-Atlantic Ridge
hot spots
Assumed stationary heat source located below the lithosphere that feeds volcanic processes near Earth’s surface
