Unit 9 Flashcards
What is continental crust
Layers of igneous, sedimentary and metamorphic rocks, that form, geological continents, a.k.a. landmass and their continental shelves
Oceanic crust
The layer of igneous rock that forms at the base of the ocean floor
Mantle
Layer of silicate rock between the rigid crust and the outer core. It’s made up of several layers that are all ultramafic (low silica)
Core
Outer core liquid inner core solid due to intense pressure, 95% iron 5% nickel
What is seismology?
The study of vibrations on and within the earth or seismic waves.
What are surface waves?
These radiate along our surface, and they form when a body wave reaches the surface
What are body waves?
These propagate through earth, and their most useful for understanding our interior. Usually all waves are caused by earthquakes including surface waves.
What is a compression wave or P wave?
These are compression waves they’re like a slinky material compresses as the wave moves past it, and they are the first wave to be detected
What are sheer waves?
These arrive after the pew waves material, vibrates as the wave moves past and it looks like a hair curl very loose
What are the two body waves?
P Aves waves or compression waves, and S waves, which are known as sheer waves
How are body waves affected by the state of the rock
We velocities increase with density, so compression waves are slow down in liquid medium, where sheer waves cannot travel through liquid. Usually this means S waves can’t go through the core.
What is the shadow zone?
Essentially where the S waves could not go through the core and what areas were not hit
How does internal temperature change with depth?
Temperature increases with depth
What is mantle convection
Heat from the core is being brought towards the surface faster so it’s heating the lower mantle material near the source gets hot, which expands and rises think of boiling water. Convection is the outer core trying to reverse the magnetic field.
What is responsible for earth magnetic field
He is transferred from the solid, inner core to the liquid, outer core and the convection of liquid iron in the outer, core, conducts, electricity, and its motion generates a magnetic field
What does isostacy
This is the rising or settling of a portion of earths solid crust that occurs when weight is removed or added, maintaining equilibrium between buoyant forces by pushing the crust up and gravity, pulling it down
Isostatic vs nonisostatic
Heavier matter will sink deeper vs matter not sinking at all
What is continental drift?
The theory that earths continents have moved over geological time relative to each other, appears as if they have drifted across the ocean
Palaeomagnetism
Earths magnetic field, magnetic field behaves, as if there was one giant magnet at the core. When magnetic materials, cool, they become digitized parallel to earth magnetic field at the time, so they retain remanent magnetism.
What is inclination and declination regarding earths magnetic field?
Inclination is the steepness/the ankle and declination is the direction