Plate Tectonics

Facts:

Layers of the Earth

Convection Currents

•Driving Force of Plate Tectonics

Seafloor Spreading

•Forces

-slab push: a force created by uprising magma at divergent plates

-slab pull: a force at a subduction zone that pulls a plate into the upper mantle.

•Magnetic Mapping-a history of Earth's magnetic field written into the rock at a divergent boundary.

•Iscochrones-an area of the seafloor with the same magnetic polarity.

 Plate Boundaries

•Convergent-when two plates collide.

•Divergent-when two plates separate.

•Transform-when two plates slide side by side.

•Subduction-when one plate moves underneath another plate.

History

•Wegner-Man responsible for the theory of plate tectonics.

•Jigsaw Pieces-An observation of how the coastline of South America and Africa are the same.

•Fossil Record-Rocks showing evidence that part of South America, Africa, Australia, India, and the Antarctic where part of one continent, Pangaea.

Vocabulary:

•Polarity-all magnetic material has a north and south end poles.

Volcanoes

Facts:

Magma is a mixture of crystals, water, gasses, and liquid rock.

•Magma is molten rock below the surface of the Earth.

•Lava is molten rock at the surface of the Earth.

Formation of Magma

•Temperature-How fast molecules are moving.

•Pressure-A force per unit applied to material.

•Water Content-The amount of water in the material that affects the melting point of rock.

-high water content low melting point (high viscosity)

-low water content high melting point (low viscosity)

Three types of Magma

•BAR-Raise the bar from Low to High

•Basaltic Magma

-low silica, gas, viscosity

-source: upper mantle

•Andesitic Magma

-medium silica, gas, viscosity

-source: ocean plate, sediments

•Rhyolitic Magma

-high silica, gas, viscosity

-source: continental plate

Types of Volcanoes

•Shield Volcano

-magma: basalt

-source: upper mantle

-cause: hot spot

-example: Hawaii

-shape: very flat circular base

-formed from layers of low viscosity magma.

•Cinder Cone

-magma: rhyoltic

-source: pocket of gas

-cause: near a subduction zone

-example: Cinder Cone South of Bend

-shape: steep sided small volcanoes

-formed from the ejection of tephra piled up around the vent

•Composite

-magma: rhyoltic

-source: subduction zone

-example: Cascade Range, Mt Hood, and Mt St Helens

-shape: cowboy hat, flat round base with a cinder cone top

-formed from layers of lava and layers of tephra

Parts of a Volcano

•Vent-the location on a volcano where lava erupts.

•Crater-the top of a volcano.

•Caldera-a volcano that has collapsed into its magma chamber.

Vocabulary:

•Viscosity-A materials resistance to flow.

-High viscosity is like cold honey.

-Low viscosity is like water.

•Tephra-any volcanic material that has been thrown into the air.

•Pyroclastic Flow-a devastatingly fast moving blast of smoke, ash, and tephra

•Lava Bomb-a large airborne tephra.

Earthquakes

Facts:

Properties of Materials

•Stress-A force per unit area.

-tension: a pull force

-compression: a push force

-shear: push and pull force

•Strain-A materials ability to resist stress.

-elastic strain: a material is able to return to original shape after a force is removed.

-elastic limit: the point at which material goes from elastic to ductile deformation.

-ductile strain: a material no longer returns to its original shape.

-fracture: the breaking point of a material.

•Stress Strain Curve shows how a material behaves when stress is applied.

 Seismic Waves

•P-Waves, Primary Waves

-compression waves

-push/pull

-similar to sound waves

-travel through the Earth

•S-Waves, Secondary Waves

-transverse waves

-shear force

-similar to a snake

-travel through parts of the Earth but stopped by liquids.

•L-Waves, “Last” Waves

-surface waves

-similar to ocean waves surface material traces a vertical circle.

-most destructive wave

-do not travel far from epicenter

Parts of an Earthquake

•Focus-the center of an Earthquake deep underground.

•Epicenter-directly above the focus on the surface of the Earth

Locating an Earthquake

•Triangulation-a method of locating an Earthquake by using three stations.

•Seismic station-a location with a seismometer.

•Seismometer-a device used to record seismic activity. Typically a frame fixed to the Earth with a suspended mass.

•Seismogram-a recording of Earthquake activity.

•Time Delay-an amount of time between a P-wave and S-wave.

Earthquake Intensity

•Modified Mercalli Scale-a scale of roman numerals from 1 to 12 used to describe Earthquake intensity.

•Intensity is a measure of how much people feel an Earthquake and how long it lasts.

Earthquake Magnitude (Energy)

•Richter Scale-a scale of 1 to 10 that rates how much energy is released from an event.

•A logarithmic scale that is multiple of ten for each number in the scale.

•A factor of 31.6 times the amount of energy.

Vocabulary:

•Deformation-when an object changes shape.

•Toughness-a materials resistance to changing shape.

•Yield-when a material allows itself to change shape.