Plate Tectonic Theory Flashcards
What are Plates?
The Earth’s crust and upper mantle (Lithosphere) are broken into sections called plates
Plates move around on top of the mantle like rafts
What is the Theory of Plate Tectonics?
Pieces of Earth’s lithosphere are in constant motion, driven by convection currents in the mantle.
Plates move slowly in different directions
Cause different geologic events (like earthquake, volcano, etc.)
What makes plates move?
Convection Currents in the mantle move the plates as the core heats the slowly-flowing asthenosphere (the elastic/plastic-like part of the mantle).
What are plate boundaries?
The edges of Earth’s plates meet at plate boundaries.
Extended deep into the lithosphere
What is a Fault?
Breaks in Earth’s crust where rocks have slipped past each other.
What are the three types of boundaries?
Divergent Boundaries
Convergent Boundaries
Transform Boundaries
Divergent Boundaries
A plate boundary where two plates move away from each other.
RIFTING causes SEAFLOOR SPREADING
“dissecting” or “dividing”
If you pull warm bubble gum or silly putty, it will thin in the middle until it is stressed so much that it breaks.
Happens on land or in water
How is the rock pulled at Divergent Boundaries?
Rock gets THIN in the middle as it is pulled apart.
Stress is called Tension
What happens when the rock SNAPS from the Stress of Tension?
Tension stress is being pulled apart
A Normal Fault (fault is a break in Earth’s crust)
Rock drops down as it breaks
Features of Divergent Boundaries
Mid-ocean ridges
rift valleys
fissure volcanoes
Where are the youngest rocks?
Under water
Seafloor Spreading
The process where new oceanic crust is formed at mid-ocean ridges and spreads outward, pushing older crust away from the ridge
In Mindcraft, Lava + water = Obsidian
What things rely on things that occur at/near divergent boundaries?
Tubeworms, Chemosynthetic Bacteria, and more
Need:
Heat
Minerals
Other Chemicals
How is the rock pushed at convergent boundaries?
A plate boundary where two plates move towards each other.
Boundaries between two plates that are colliding
Called Compression
Convergent Boundaries
Places where plates crash (or crunch) together or subduct (one sinks under)
Compression
What are the 3 types of Convergent Boundaries?
- Ocean plate colliding with a less dense continental plate (ocean to continental)
Andes Mountains, South America - Ocean plate colliding with another ocean plate (Ocean to Ocean)
Aleutian Islands, Alaska - A continental plate colliding with another continental plate (Continent to continent)
Mountain Ridges
Subduction Zone
Convergent Boundary
Where oceanic crust sinks beneath a deep-ocean trench and back into the mantle at a convergent plate boundary.
What happens at subduction zones or convergent boundaries?
Volcanos
What is a Trench?
a subduction zone where the more dense plate slides under the less dense plate
Happened in ocean to ocean convergent boundary
What is a collision zone?
A place where folded and thrust faulted mountains form.
Continental to continental
What happens when the rock is squeezed from the Stress of Compression?
A REVERSE FAULT
Rock is forced upward as it is squeezed.
What is a Reverse Fault
Rock is forced upward as it is squeezed.
Transform Boundaries
A plate boundary where two plates move past each other in opposite direction. (side by side)
How is the rock broken at Transform Boundaries?
Rock is pushed in two opposite directions (or sideways, but no rock is lost)
Sheering
What is Sheering?
Rock is pushed in two opposite directions (or sideways, but no rock is lost)
Cut
A STRIKE-SLIP FAULT
Rocks on each side of the fault slip past each other as they break.
What happens at Transform Boundaries?
Earthquakes
San Andreas Fault in California
Transform boundaries run like trains going past each other in different directions & they shake the ground!
What are combination Boundaries?
Transform boundaries occur in Zig-Zags with Divergent or Convergent Boundaries
What is a strike-slip Fault?
Rocks on each side of the fault slip past each other as they break.
