Quiz 1 Flashcards
Spreading at a mid-ocean ridges occurs at what rates?
Centimeters per year
Rocks beneath the sea floor that were once melt within a mid-ocean ridge magma chamber are called?
Gabbro
Two kinds of lava flows on the sea floor are called?
Pillow flows and sheet flows
Significant discoveries that helped drive the transformational theory of plate tectonics include?
- Periodic reversals in earths magnetic field.
- Documentation of seismic activity concentrated along subduction zones and spreading centers
- Continental drift
The oceans cover what percent of the surface of the earth?
70%
Major features within the oceans that define plate boundaries include?
Subduction zones (convergent) Mid-ocean ridges (divergent)
Common characteristics of a fast-spreading center include?
Frequent eruptions and narrow axial valley
Also, slow spreading centers will be the opposite
Convection occurs where?
Cold seawater is heated by underlying magmatic rock
Novel organisms that thrive beneath the seafloor live?
- At temperatures greater than 200 F
- Lack of oxygen
- Multiply fast after eruptions
- Genetically ancient
- Utilize toxic materials
The oceanic lithosphere is composed of?
Dikes and lavas
Magma chambers typically occur at depths of?
1-5 km under the seafloor
Submarine volcanoes erupt because?
They are enriched in CO2
What is a subduction zone?
at convergent boundaries, one tectonic plate moves under another tectonic plate and sinks into the mantle as the plates converge.
What is a mid-ocean ridge?
an underwater mountain system that consists of various mountain ranges, typically having a valley known as a rift running along its spine, formed by plate tectonics.
Magma vs lava?
Magma: molten rock underground
Lava: magma above ground
