Chapter two: Plate tectonics Flashcards
active continental margins
Plate Boundaries
Passive continental margins
Are not plate boundaries
Margin
boundary between a continent and an ocean
Continental Shelf
Thick sediment cover, gentle
slope, shallow to moderate
depth
Abyssal Plain
nearly flat
in slope, deep depth,
overlies oceanic crust
How many type of plate boundaries are there ?
3
what are the types of plate boundaries
1- Divergent
2- Convergent
3- Transform
Type 1 - Divergent Plate Boundary
Two plates that pull away or separate
from each other. Produces new crust
Effect of movement – Sea Floor Spreading
Magma wells up to fill the gap.
* Magma cools, adding material to each plate.
Type 2 - Convergent Plate Boundary
Two plates that move towards or
collide with each other. Consume old crust
Effect of movement – Subduction or Collision
Type 3 - Transform Plate Boundary
Two plates that slide horizontally past each
other. Does NOT consume or create crust - Transform (sideways slipping) motion
Mid-Ocean Ridges
Linear mountain ranges in Earth’s ocean basins.
Why Are Mid-Ocean Ridges Elevated?
New oceanic crust is warmer and less dense, and very
little lithosphere has been added, close to the ridges.
Older crust is cooler and denser, and the thicker
lithospheric mantle adds even more weight, pulling the
whole lithosphere down into the asthenosphere
Triple Junctions
Where three plates meet.
Hot Spots
Hot spots arise from hot mantle plumes that are stationary through timeand buoyantly rise through the crust,
P-waves
emitted by earthquakes travel through both solids and liquids
S-waves
emitted by earthquakes travel only through solids
Earths core
Earths core is thought to be be rich in iron and Nickel
Mountain chains
Mountain building also known as orogenesis.
Normal faults
occur when a block of rock, called the hanging wall moves downward relative to the block on the other side of the fault, called the footwall
Reverse faults
are the opposite of normal faults. in reverse the hanging wall moves up relative to the footwall
thrust fault
A particular reverse fault in which the angle of the fault is quite low or nearly horizontal.
strike spilt fault
involve horizontal movements of rocks relative to each other along the fault
What is the largest tectonic plate?
the Pacific Plate
