Units 26-27 Flashcards
What are the five categories of evidence that teach us about earth’s interior?
- Direct observation of rocks from interior
- Relationships to rocks or meteorites from space
- Inferences from Earth’s density
- Evidence from seismic (earthquake) waves
- Requirements for producing Earth’s magnetic field
What brings deep rocks to the surface that can’t be reached by drilling or other ways?
Volcano blasts and ascending magmas.
Crust
The uppermost compositional layer of Earth.
Characteristics of the crust:
Very thin
Composed of two parts: Granitic continental crust and basaltic oceanic crust
True or False: Rocks brought to the surface by volcanoes are denser than the basalts on the ocean floor.
True
Mantle
The middle compositional layer of earth.
Characteristics of Mantle:
Thick layer
Made of peridotite in the upper part
and higher density rocks of peridotite composition in the lower part.
Peridotite
Rock made up of mostly silicon, oxygen, iron, and magnesium.
True or False: Peridotite is denser than the basalt and granite of the earth’s crust
True
Meteorites
A rock from space that HITS earth’s surface
Stony chondrites
Meteorites thought to be composed of unprocessed material from the original solar nebula
The same materials that our planet and solar system were originally made.
What percentage of meteorites are stony chondrites?
86%
Stony achondrites
Meteorites thought to represent material from small planetary bodies that had differentiated into layers and then were broken up.
What percentage of meteorites are stony achondrites?
8%
Iron meteorites
Meteorites thought to represent the type of material found in Earth’s core
What percentage of meteorites are iron?
6%
Core
The deepest or central compositional layer of Earth. It is composed mostly of iron
What is the equation for Earth’s mass?
M = gR^2 / G
M = mass of earth
g = acceleration of gravity
R = radius of earth
Why do we care what Earth’s density is?
Because that tells us about the rocks that compose it.
Why do we care about Earth’s mass?
Because having the mass lets us calculate density
True or False: Earth’s surface is elastic
True
It rebounds back into shape when pressure is released
Elastic rebound
The point at which stress in Earth’s lithosphere is strained to a point where it can bend no further. When this happens, the lithosphere ruptures and rebounds somewhat like a rubber band that has just been pulled apart.
Fault
A break in earth’s lithosphere where rocks on one side of the break have slipped past the rocks on the other side
What causes faults exclusively?
Earthquakes