Chapter 2 - PREMIDTERM Flashcards
What is a divergent plate margin?
Moving apart, new crust forms
What force acts on transformation shear margins?
SHEAR
Describe oceanic oceanic boundaries
2 plates converge along the boundaries, subducting plate bends downward to form oceanic trench. As it subducts, generates magma, rises and forms a curved chain of volcanic islands called volcanic island arc . They are almost parallel to the oceanic trenches.
In areas where rate of subduction is faster than the forward movement of overriding plate, formation of back arc basins
How deep is mantle
2900km
how deep is core
6370km
-SAME AS RADIUS
radius of earth?
6370km !@#!@# SAME AS DEPTH OF CORE SILLY
Thickest plate?
Continental
How thick are continental plates
20-90km
How deep is the asthenosphere? SOLID LIQUID OR GAS? Right Under aesthenosphe, solid? liquid? gas?
660km. SOLID, but very viscous
under: SOLID! way less viscous, more pressure. But outer core turns liquid
Most abundant element in earth core?
IRON
Compare inner and outer core,. liquid liquid solid solid solid liquid???
outer core is liquid
- inner core is solid
- this is due to pressure
When do black arc basins form
When rate of subduction is faster than forward movement of overriding plate (oceanic oceanic boundaries)
Describe continental and oceaning plate boundaires
- denser oceaning plate subducts at boundary
- trench formed, volcano on land
Describe oceanic oceaning plat boundaries
volcanic arc forms
- more dense plate subducts
- trenches form
describe continental continental boundaries
mountains!!
Result of diveregence
- active volcanoes present during
- as it continues, ocean basins created
Transform boundaries, Where, results? WHAT FORECE
-along seafloors
-plates slide along each other parallel to direction of movement
-SHEAR ^^^
Results in earthquakes
-lithosphere not created/destroyed
What plate action is the only one that doesn’t create/destroy lithosphere
transform
Driving force of transform?
earths convection currents
Who did theory of plate tectonics?
Alfre wegener
Convergence of evidence for Pangea?
- Geographyral
- stratigraphy
- structural geography
- glaciology
- paleontology
- paleomagnetics
- distribution of volcanoes
- distribution of earthquakes
Convergence of evidence for Pangea? Geography
- The theory couldn’t explain the small gaps between continents
- BUT plates don’t end on shore line, they do farther in ocean
Convergence of evidence for Pangea? Stratigraphy
looking at rocks seeing them similar in different continents, wouldn’t be possible if ocean in between
Convergence of evidence for Pangea? Structural geography
Like mountains ranges stopping abruptly in Iceland, then come in greenland
Convergence of evidence for Pangea? glaciology
striations (lines scratched into rock surface) shows glacial movements, only makes sense if continents moved how they did
Convergence of evidence for Pangea? Paleontology
Certain fossils in 2 different countries
Convergence of evidence for Pangea? Paleomagnetics
- we can measure magnetics in rocks from salts that solidified
- salts align themselves to magnetic north pole
- can track where that plate was when rock was formed from direction if we know polar migration of north pole
In what period is the oldest crust?
Jurassic
Convergence of evidence for Pangea? Distribution of volcanoes
volcanoes come up where plate meet, ring of fire
-volcanisms in middle of nowhere , mantle convections,
Convergence of evidence for Pangea? distribution of earthquakes
idk youlo
