Chapter 32: Vocab Flashcards
A machine that measure seismic waves.
Seismograph
Waves that travel through the Earths interior.
Body waves
Fastest waves that compress and expand rock. Can travel through anything.
Primary waves (p waves)
Transverse. Particles travel perpendicular to the direction of wave motion. Can travel only through solids.
Secondary waves (s waves)
Travel on the earths surface.
Surface waves
Waves that move up and down.
Rayleigh waves
Waves that move side to side and are the slowest.
Love waves
Separates the crust from the mantle.
Mohorovoicic discontinuity
Composed of iron and nickel.
Core
Solid layer of the earth.
Inner core
Movement of the outer core helps create the earths magnetic field.
Outer core
Surrounds the core, 3000 km thick.
Mantle
Lower part of the upper mantle. Flows like plastic.
Asthenosphere
100 km thick, includes the upper portion upper mantle and the crust.
Lithosphere
The top part of the lithosphere varies in depth. Oceanic
Crust- 10 km thick. Continental crust- 20-60 km thick.
Crust
Compression of rocks cause the Earth’s crust to bend.
Fold
Rocks that are folded or pushed downward.
Syncline
Rocks that are pushed upward.
Anticline
Rocks that are under pressure and actually break.
Fault
The rock that is above the fault plane.
Hanging wall
The rock that is below the fault plane.
Footwall
Hanging wall that drops below the footwall.
Normal fault
The hanging wall moves above the footwall. (Rockies)
Reverse fault
Footwall and hanging wall move horizontally past each other. (San Andreas fault)
Strike slip fault
Measures amplitude of seismic waves. Logarithmic. Energy/ magnitude.
Richter scale
Measures damage caused by earthquake.
Mercalli scale
All the continents were once connected into a single supercontinent.
Pangaea
Proposed by Alfred wegener. The idea that all the continents were connected and over time have moved to their current locations.
Continental drift
Proposed by H. H. Hess. Convection cells in the mantle push new material up to the surface at mid ocean ridges. Older lithospheric material will be found farther from the mid ocean ridge.
Seafloor spreading
The earths lithosphere is divided into several large plates that ride on the asthenosphere. Earthquakes, volcanoes, and mountains typically occur at plate boundaries.
Theory of plate tectonics
Plate boundary with plates moving apart. (Mid Atlantic ridge)
Divergent boundary
Plate boundary with plates that run into each other.
Convergent boundary
One plate is forced under the other plate, creates an oceanic trench.
Subduction
The more dense plate is pushed downward, creates island arcs.
Oceanic-oceanic
Oceanic plate is subducted. Creates active volcanoes and mountains.
Oceanic- continental
The plates break and fold on each other; form mountains (Himalayas). Earthquakes are common but no subduction.
Continental-continental
Plates are sliding past each other. No subduction, earthquakes are common. (Strike-slip fault) (San Andreas fault)
Transform fault
Earthquake generated waves.
Seismic waves
