Earth's Structure Flashcards
How many lithospheric plates are there?
12 large ones and several smaller ones
When was the continental drift theory proposed and by who?
Proposed in 1912 by Alfred Wegener
Divergent plate boundaries
- seafloor plate separation
- continental plate separation
Convergent plate boundaries
- ocean-continent
- ocean-ocean
- continent-continent
Transform plate boundaties
-shift in a “shearing” motion
Sources of energy for plate motion
- 80% radioactive decay
- 20% remnant heat from Earth formation
Hot spots
- areas where columns of hot mantke materiak underlie the lithosphere
- stationary relative to plates, can create chains of volcanic islands
Energy
the ability to do work, causes things to move or change
Forms of energy
- gravitational
- thermal
- chemical
- radiant
- nuclear
- elastic (strain)
Physical laws of energy
- cannot be created or destroyed
- entropy always increases
Sources of energy
- external (solar energy makes up 99.9% of total energy reaching Earth’s surface)
- internal (radioactive decay, remnant heat from Earth formation)
Remant heat causes:
- powers volcanoes and earthquakes
- pushes up mountains (indirectly powers landslides)
Solar energy causes:
- motion in the atmosphere and oceans
- powers waves and storms
Gravity powers:
- landslides
- impacts
elastic energy:
- builds up as plates move and faults lock
- crust deforms and stores elastic energy
- elactic energy released as heat/seismic waves when fault
Stress
- force per unit area
- can be parallel or perpendicular
- causes strain
Strain
- deformation response to an applied stress
- elastic deformation (reversible)
- plastic deformation (irreversible)
Faults
-Geologic structures along which displacement has occurred
Normal fault
hanging wall moves down fault plane
Reverse fault
hanging wall moves up fault plane
thrust fault
low angle reverse fault
strike-slip fault
vertical fault, lateral motion (right/left)
Mineral
- naturally occurring
- inorganic solid
- definite chemical composure
Rock
a solid aggregate or mass of minerals
How many minerals have been identified on earth?
Nearly 4,000
Igneous rocks
form from magma that originates deep in the earth and moves up toward the surface
What percent of magma reaches earth’s surface?
10%
Magma crystallizes in the interior as _____
intrusions
Sedimentary rocks
formed by compression, dehydration, cementation of
sediments
Metamorphic rocks
The transition of one rock into another by temperatures, pressures and/or chemical conditions unlike those in which it formed
Rock cycle
The processes and paths by which one rock type is converted to another, both within the earth and at the surface
Hydrologic cycle
Solar energy drives movement of water between atmosphere and oceans and continents
Biogeochemical cycle
Transfer of chemical elements through a series of reservoirs
