Tectonic Processes Flashcards
What are three pieces of evidence of continental drift?
- jigsaw fit
- fossil remains of freshwater reptile in South America and Africa
- Coal in Antarctica (couldn’t form there at current latitude)
explain mantle convection
radioactive decay in the inner core causes magma in lower mantle to rise into the asthenosphere. it cools and sinks in a circular motion causing a convection current.
What is paleomagnetism?
the study of the earth’s magnetic field
What is seafloor spreading?
magma is forced up from the asthenosphere, forcing apart the crust and hardens to form new crust
How does paleomagnetism prove seafloor spreading?
the change in direction of the earth’s magnetic field every 400,000 years matches the change in the direction of the minerals inside the rock (cooled lava). hence new rock formed at the same time on both sides
What is subduction and what does it prove the earth is not doing?
two plates collide, the denser subducts and melts. hence showing the earth is not expanding
What is slab pull?
crust pulls apart and subducts due to the weight of the magma
what are the two different types of waves?
Body waves and surface waves
what are body waves and what are the two types of body waves?
body waves move through the earth’s ‘body’.
- P waves
- S waves
what are surface waves and what are the two types of surface waves?
move through the surface/ crust only
- Love waves
- Rayleigh waves
what are the four characteristics of P waves?
- fastest wave
- first to reach surface
- travel through solids and liquids
- compress/ expand crust
what are the four characteristics of S waves?
- 60% speed of p waves
- travel through solids
- move crust up/ down
- more damaging than p waves
what are the three characteristics of Love waves?
- fastest surface wave
- move crust side to side
- most damaging
what are the two characteristics of Rayleigh waves?
- travel with rolling motions
2. move crust up/ down
what are the two theories to explain intraplate earthquakes?
- stress builds along ancient faults causing them to become active
- crust that was once weighted down by glaciers is slowly rebounding from mantle