Physical Geography (copy) (copy)

Plate Tectonics

Plate Tectonics

The study of the movement of large plates across the Earth's surface

Alfred Wagner

scientist who came up with the continental drift theory

Book Alfred Wagner

The Origins of the Continents and Oceans

Amount of water on earth

70% of Earth is water

Amount fresh water vs salt water

3% - 97%

Amount of land on Earth

30%

Tillable land vs non tillable land

6% - 24%

Amount of major plates

24

Largest continental plate

Eurasian Plate

Largest Ocean plate

Pacific plate

Divergent plate boundary

Boundary between tectonic plates in which the two plates move away from each other, and new crust is created between them

Divergent Plate results

Volcanoes

Convergent plate boundary

A tectonic plate boundary where two plates collide, come together, or crash into each other.

Convergent plates

Heavier one goes below the lighter one

Types of convergent Boundaries

Oceanic-continental, oceanic-oceanic, continental-continental

Continent-continent convergence

Where two continental plates collide and one may subduct beneath the other - NO VOLCANOES

Ocean-ocean convergence

Where two oceanic plates converge and one usually subducts beneath the other

Ocean-Continent convergence

a plate boundary where oceanic crust meets continental crust, oceanic crust subducts

Transform boundaries

where plates slide past each other, also known as a fault

Types of Faults

normal, reverse, strike-slip

Normal Fault

A type of fault where the hanging wall slides downward and the footwall pushes up; caused by tension in the crust

Normal fault causes

Created by a divergent boundary

Reverse fault

Hanging wall slides up while footwall slides down

Reverse fault causes

Created by a convergent boundary

Strike-slip fault

a type of fault where rocks on either side move past each other sideways with little up or down motion

Strike-slip causes

Created by a transform boundary

Hotspots

Random places across the Earth's crust that are exceptionally hot, which allows for volcanism

Volcanoes places

occur along divergent boundaries and ocean-ocean and ocean-continent convergent boundaries

3 types of volcanoes

shield, cinder cone, composite

Strata/composite volcanoes

Most explosive volcanoes, built like a mountain, lava is very thick

Location of Strata/Composite volcanoes

Subduction zones

Subduction zones

One plate goes underneath another plate and it is melted

cinder cone volcano

Very small, most common volcanoes which usually have one major Strombolian eruption

Strombolian eruptions

Not very widespread but can still devastate areas close to it, with very runny lava

Shield Volcanoes

a wide, gently sloping mountain made of layers of lava and formed by quiet eruptions, low viscosity lava

Lava Tube

The empty space left when a lava tunnel drains

Caldera

a large crater caused by the violent explosion of a volcano that fills with water

Lava Dome

Domes in the crater of a stratavolcano that have formed into the eruption of slow moving lava,

Hummocks

Giant rocks left from a volcanic landslide/hills

Earthquakes

Vibration that occurs in the Earth's surface

First Earthquake recorded

China - 1177 BC

Most leathal Earthquake

China - 1556 - killing 688000

Why shocks occur

Stress that one quake places on the surrounding fault lines

Earthquakes location usually

Around fault lines and plate boundaries/transform and convergent zones

Seismographs

measures and records earthquake magnitude based on the energy released in an earthquake.

Seismic waves

Energy that is released by an earthquake when the plates fracture or slip

Types of body waves

P(rimary), S(econdary) and Surface waves

Primary waves

Fastest waves causing little damage

Secondary waves

Moves more slowly causing more damage

Surface waves

Long waves that move up and down, cause a lot of damage

Richter scale

magnitude increases 10X per whole number

Mercalli scale

A scale that rates earthquakes according to their intensity and how much damage they cause at a particular place

FEMA

Federal Emergency Management Agency

Difference between erosion and weathering

There is no transportation in weathering. the actual removal of weathered material is erosion

Types of Erosion

Thermal, Wind, Water, Glacier

Thermal Erosion

Result of melting permafrost and weakening permafrost because of water and rising temps

Permafrost

Permanently frozen ground

Wind Erosion

Occurs in large flat areas, not where vegetation is

Deflation

Wind erosion - process of small particles (loess) being lifted and moved to another region

Abrasion

Wind erosion - process by which an area has its surface removed by transported loess, 3 types of

Creep

Rock that is to heavy to be carried through erosion, so it is pushed across ice in a desert during night

Sailing Stones

Creep stones

Saltation

Wind erosion - carrying of particles several meters and bouncing off the ground

Suspension

Wind erosion - carrying of particles in the air

Types of Water Erosion

Rill, Gully, Streambank, Shoreline

Rill Erosion

Water erosion - concentrated flow of small amounts of water in ground, usually from rain

Gully erosion

Water erosion - Large amounts of water flowing in an enclosed area of AT LEAST A FOOT IN DEPTH

Streambank Erosion

Water erosion - Occurs along large consistent currents like rivers - When rivers smash against the wall when the river curves

Shoreline Erosion

Water Erosion - Taking sand somewhere from the shoreline

Weathering

Removal of something

Mechanical Weathering

Process by which the earth is physically broken down

Chemical Weathering

The breaking down of rocks through chemical decomposition by adding or taking important molecules

Types of Chemical Weathering

Carbonation, Hydration, Hydrolysis, and Oxidation

Acronym for the types of chemical weathering

CHHO

Droughts

Shortage of Water that can happen everywhere

Monsoon

A lot of rain in a certain area; can be seasonal, or random, can happen because of different temperatures between the land and the water, wind changes, or just the seasons

Location where monsoons happen prominently

Southeast Asia - Indian Ocean

Winter Season Monsoons

Areas are dominated by a strong high pressure area, and then the monsoon brings several months of dry, clear, cold weather, not rain

Summer Season Monsoons

Winds from the adjacent oceans blow on the land; low pressure on land, high pressure over the sea

El Niño duration

About a year, happens 2-7 years

El Niño

The east to west winds slow down in the South Pacific, and cold waters rise up in the west, pushing the warm water to the East

La Niña

When trade winds go faster, allowing cold water to rise in the east, and warm water to rise in the west

Continental Effect

A big body of water affecting the temperature of land

Orographic effect

Process when rain falls because clouds can’t go above the mountain

Snow

ice that doesn’t melt by the time it gets to earth

Darker clouds

Are more dense so they let less sunlight through - making them look darker

Sleet

Partially melted snow

Hail

Produced in a thunderstorm, starts off as ice, and when getting bounced around in the storm, gains more ice particles around it, and it falls

Number of thunderstorms per day

1800 per day, usually 30 min and spread 15 miles across

Storms require…

Moisture and warm rising air

Storms are most prevelant in…

The middle of continents - where weather changes a lot

Thunderstorms

Need warm, humid climates

Lightning

Occurs due to a negative charge at the base of the cloud, which pushes negatively charged particles deeper in the Earth. Then the positively charged particles come to the surface and up to the cloud, which then only needs a conductor to happen

Thunder

Movement through the air molecules; the lightning strikes, and then all of the molecules crack (billions)

Thunder real world example

Dropping a cube of ice into room temp water

“Calm before the storm”

Has to have a big storm; the cloud takes all of the warm molecules in front of the storm and cold air gets pushed out, creating an eerie sense right in front of the storm

Clouds

Formed by evaporation and the collection of water

Rain

When clouds have too many water droplets

Hail cause

When rain or snow is blown around, and that rain/snow is collected in the form of crystals until it is too heavy to remain aloft