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34 Cards in this Set

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  • Back
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Where is new lithospheric material created?
The Oceanic Ridge & Rise System
The Oceanic Ridge & Rise System is what kind of plate boundary?
Magma erupting from the OCR&RS consists of what kind of earth?
Dealing with oceanic crust after all...
Divergent Plate Boundary:
- Earthquakes? abundance/depth
- Volcanic Activity?
- Heat flow high, medium, or low?
- Common amt of earthquakes
- Abundant volcanic activity
- High heat flow
Why does the OCR&RS have shallow earthquakes?
Rising asthenosphere & magma bring heat close to the surface, such that close-to-melting earth flows instead of breaking
Imagine a freshly baked (and warm!) cookie vs. a hardened (and cold!) cookie...
How old is the lithospheric material usually when destroyed by subduction?
It is denser than the material that is atop it, and thus older & colder as well.
Zones of subduction are also known as:
Deep ocean trenches
A bi-product of subduction is:
Magmatic arcs (of volcanoes)
Chain of __ parallel to trenches & above subducted slabs of lithosphere
How is a magmatic arc formed in subduction?
Magma rises to surface through cracks in the overriding plate.
You can't always push one rock under another perfectly, can you?
Convergent Plate Boundary:
- Earthquakes? abundance/depth
- Volcanic Activity?
- Is the heat flow high, medium or low?
- Abundant (Range from shallow to deep)
- Abundant/Common
- Arc: High, Trench: Low
There are arcs & trenches btw...
Explain how two plates move in a transform fault
They move parallel to each other in opposite direction
Of the two parts of a transform fault, which is the seismically quiet zone and which is where the action occurs?
Quiet - Fracture Zone
Not so quiet - Transform
What fills the gap between two diverging lithospheric plates?
3 types of divergent plate boundaries?
1 - OR&RS
2 - Young ocean basins (intermediate stages of continental rifting & ocean-basin formation)
3 - On-land rifting (characterized by abnormally high heat flow & extensive faulting w/ volcanic activity)
Think of faulting, rifting and volcanic activity
3 types of convergent plate boundaries?
1 - OceanicPlate to OceanicPlate
2 - OceanicPlate to ContinentalPlate
3 - ContinentalPlate to ContinentalPlate
Explain OceanicPlate to OceanicPlate convergence.
Subduction of older, colder, more denser oceanic plate, with the less dense, younger, warmer crust formed over it. Forms deep ocean trenches and associated volcanic island arcs.
Hot Young-Ins
Cooled down Old-timers
Explain OceanicPlate to ContinentalPlate convergence.
Subduction of high-density oceanic plate beneath lower-density continental plate, making an oceanic trench parallel to continent with chain of volcanic mtns on the continent.
Helps to think about it picture-wise.
Explain ContinentalPlate to ContinentalPlate convergence.
Intense compression of the continental rocks occurs. Linear belts of folded mtns along the suture zone are forms.
Remember that no matter how less dense 1 continent plate is to other, they're both less dense than the asthenosphere beneath them.
What are 2 types of transform faults?
1 - Ridge transforms (oriented perpendicular to axes of mid-ocean ridges, offsetting the ridge axes)
2 - On-land transforms (2 continental blocks slide past each other)
Interiors of plates
What are large pulses/plumes of basaltic magma from deep mantle sources?
What has given birth to the Hawaiian island chain of volcanoes and the Emperor Seamount chain in the North Pacific?
Hotspots that remain permanently in one spot while the lithospheric plate continues to move over long periods of time.
Transform Plate Boundary:
- Earthquakes? abundance/depth
- Volcanic Activity?
- Is the heat flow high, medium or low?
- Abundant (Shallow)
- No Volcanic Activity
- MidOceanRidge: High
- OnLand: Low
- Earthquakes? abundance/depth
- Volcanic Activity?
- Is the heat flow high, medium or low?
- Common (Because of active plate motion as volcanic chain continues)
- Abundant
- High
Intraplate Region:
- Earthquakes? abundance/depth
- Volcanic Activity?
- Is the heat flow high, medium or low?
- Rare
- Rare
- Low
What dictates a left-lateral vs a right lateral?
Which direction is the opposing parallel plate moving in?
Sinistral strike slip fault?
Dextral strike-slip fault?
What is the fracture zone?
A scar of a ridge transform
aka why does it exist?
Formula for the spreading rate of a ridge or a rise?
Distance Traveled
Keywords: Spreading Rate of this divergent plate boundary
What's the main difference(s) between a ridge and a rise?
A rise is more broad with small rift valleys if any.
A ridge is more pointed with a deep rift valley
Rise ~= Plain + crack

Ridge = Tall, skinny mtn with a canyon inside
Mid-Atlantic Ridge
East Pacific Rise
Ranges for Convergent Margin Earthquakes:
- Shallow?
- Intermediate?
- Deep?
1) 0-30 km
2) 30-400 km
3) 400-700 km