4.1 Review

Outer solid layer of the earth

crust

Middle semisolid layer of the earth

mantle

Inner portion of the earth

core

Crust and upper mantle (solid layer of the earth)

lithosphere

Layer between the upper and lower mantle on which the continents move

asthenosphere

Division between the crust and upper mantle

mohorovicic discontinuity

Magma which comes to the surface in the middle of a plate

hotspot

Term for the large land mass which is all together in Continental Drift

Pangea

Tectonic boundary where plates move apart

divergent (have underwater ridges, islands, vents, rift valleys)

Tectonic boundary where plates come together

convergent (ocean-ocean: trenches and island arcs—not the Hawaiian Islands—Japan; land-land: mountains; ocean-land: trenches and coastal mountains—Andes, Appalachian)

Term for melting of one plate when it is forced under another

transform

Structure formed when magma comes to the surface

volcano

Structure formed at the edge of a subduction zone

trench/island arc

How many major tectonic plates are there?

15

Who originated the theory of continental drift?

Alfred Wegener

What evidence is there for continental drift?

maps showed that continents have jigsaw like pieces (i.e. Africa and South America) and shared fossils across continents

What structures form at divergent boundaries?

underwater mountain ranges

What structures form at convergent boundaries between two ocean plates?

ocean trenches, island arcs

What structures form at convergent boundaries between an ocean and a continental plate?

trenches, coastal mountains

What structures form at convergent boundaries between two continental plates?

mountains

What structures form at transform boundaries?

faults

What causes tsunamis?

any event that displaces a massive amount of water

What causes earthquakes along transform boundaries?

earth builds up stress by catching on loose rocks on the edges; when the stress is relieved, there is an earthquake

What causes volcanoes and island arcs along subduction zones?

subduction generates a lot of heat, which leads to magma coming up to the surface, cooling, and then forming mountains

Rock formed directly by cooling of molten magma

igneous rock

Rock formed by compression of sediments

sedimentary rock

Rock formed by exposure of existing rock to high temperature and pressure

metamorphic

Breakdown of rocks by natural causes

weathering

What is the source for all rocks on the earth's surface?

magma

What are two examples of igneous rocks?

obsidian, basalt, granite

Where is most basaltic rock found?

on the ocean floor

Where is most granitic rock found?

underneath the ground in a land mass

Which kind of rock contain fossils?

sedimentary

Name two common metamorphic rocks.

slate, marble

Name two common sedimentary rocks.

limestone, sandstone, conglomerate