Earth's Changing Face: The Basics of Plate Tectonics (L14) Flashcards
What is the system of rock recycling called?
Rock Cycle
How does an igneous rock become a sedimentary rock?
The igneous rock can be exposed to weathering to produce particles that are eroded, transported, and deposited as sediment. When lithified, it becomes sedimentary rock
How does a sedimentary rock become an igneous rock?
sedimentary rock melted to produce magma, then cooled to produce igneous rock.
Sedimentary rock to Metamorphic rock?
sedimentary rock put under high temperatures and pressures
Metamorphic to Sedimentary Rock?
metamorphic rock can be weathered to produce particles that are eroded, transported, and deposited as sediment
Metamorphic to Igneous?
metamorphic rock can be melted to produce magma that cools to become an igneous rock
Igneous Rock to Metamorphic rock?
igneous rock put under high heat and pressure to become metamorphic rock
What is one of the reasons why movement takes place on the Earth’s surface?
because heat flow within the Earth is not uniform
how does hot material and cold material flow throughout the mantle?
hot material flows upwards, cold material flows downwards
What produces the huge convection currents in the mesosphere
the cells of rising and sinking mantle
what material in the mantle, flows most readily and why?
the Asthenosphere, because it is solid, but in a near-liquid state
what is the boundary between the mantle and crustal part of the lithosphere called?
the Mohorovicic Discontinuity or “Moho” for short
the lithosphere (the brittle outer shell of the Earth, is not a continuous sheet but rather ____
broken into tectonic plates
Explain how the plates of lithosphere actually move
through something called Convection.
Convection currents in the asthensophere drag the pieces of lithospheric plates along on the surface called “Mantle drag”
What happens to the places where the plates were moved apart ?
the asthenosphere fills the cracks and spots where the plates moved apart while the far edges of the plates of lithospheric plates are dragged down by downgoing currents
Where do ridges form?
where the lithospheric plates are being formed as the new lithospheric plates are least dense
What happens when lithospheric plate cools?
it increases greatly in density and sinks and drags the rest of plate along with it
“slab pull”
the movement resulting from the pulling of a plate down a trench by the dense edge of a plate
what does slab pull cause?
causes the old, outer edge of a plate to sink
At the present time, what is thought to create the majority of plate movement?
a combination of slab-pull and convection
what are the 2 Main types of boundaries?
A divergent boundary - the boundary between 2 plates that are moving APART
A convergent boudnary - the boundary between 2 plates that are moving toward one another (Converging)
what are divergent boundaries represented by in the ocean floor?
mid-ocean ridges (e.g., East Pacific Rise, Mid-Atlantic Ridge)
what are convergent boundaries represented by?
Trenches
The 2 types of Crust
Oceanic Crust (mafic crust underlying the oceans) Continental Crust (felsic crust that underlies the continents)