Geography Unit 2 - Physical Geography Part A

big bang theory

15 billion years ago a super large star went NOVA, after billions of years the matter began to slow down and gravity pulled it together which created galaxies, solar systems, planets, stars, etc. earth began to form approximately 4.6 billion years ago

theory of evolution build up

in 1700s Charles Darwin began a trip around the world, he stopped in the Galapagos' Islands and began to study birds and realized that birds on different islands have different beaks

theory of evolution

species developed according to their needs and that they adapt to survive

inner core

hottest part of the earth, made up of nickel, gravity stops the material from turning to liquid

outer core

made up of liquid iron and nickel, it is like heavy metals and jello, semi solid rock

mantle

made up of liquid rock (magma)

crust

earths outer surface, 80-500km thick, thinner under the ocean, thicker under the continents, magma moves about in convection currents

continental drift proof 1

south america and africa appear to have a jigsaw puzzle fit

continental drift proof 2

similar plant and animal fossils are found both in south america and africa

continental drift proof 3

mountains similar in age and structure are found on both sides on the atlantic ocean

continental drift proof 4

ice sheets once covered parts of south america, africa, india and Australia which means that at one point of time these land masses were located much closer to antarctica

problem with continental drift theory

wegner could not explain what mechanism was strong enough to move the continents, therefore his theory was not accepted by his colleagues

plate tectonics

plates (large pieces of the earths crust) sit on liquid magma, moves by convection currents

marie tharp

A geologist and an oceanographer who mapped the ocean floor and proved plate tectonics

J. Tuzo Wilson

canadian geophysicist who made major contributions to the development of the plate tectonics theory

first point J. Tuzo Wilson suggested

the hawaiin and other volcanic island chains may have formed due to the movement of a plate over a stationary "hotspot" in the mantle

second point J. Tuzo Wilson suggested

there must be a third type of plate boundary, proved transform boundaries

process of divergent/separating plate boundaries

both plates will get larger as magma comes up and fills in the space, most of the worlds volcanoes occur along divergent plate boundaries

divergent/separating plate boundaries

two plates move apart, most commonly appears along a mid ocean ridge although it may occur on land too

results of divergent/separating plate boundaries

lift valley/ridge, new rock is formed where the plates separate (e.g. mid-atlantic rift valley)

convergent/colliding plates

two plates move towards each other

three types of convergence

continental and oceanic plates, continental and continental plates, oceanic and oceanic plates

continental and oceanic plates

oceanic plate gets pushed under continental plate back into the mantle creating a subduction zone

continental and continental plates

Form mountains as crust folds together, like the Himalayas

oceanic and oceanic plates

one plate usually dives beneath another forming deep trenches (e.g. mariana trench), can sometimes cause underwater volcanoes that eventually build up into island arcs like japan

transform/sliding plates

plates move parallel or horizontally past each other which causes friction, when energy is released it can cause an earthquake

three main areas of volcanic activity

convergent plate boundaries, divergent plate boundaries, hot spots

convergent plate boundaries (volcanoes)

plates collide into one another (e.g. Mt. Saint Helen)

divergent plate boundaries (volcanoes)

plates move apart while magma comes through the surface and erupts (e.g. submarine volcanoes)

hot spots

occur in the middle of the plates, magma melts through the plate and erupts (e.g. Hawaiian chain of volcanoes)

types of volcanoes

shield, cinder cone, composite/stratovolcanoes

shield volcanoes

built up from multiple eruptions of flowing lava, broad, gently sloping sides

cinder cone volcanoes

small, cone shaped hill usually less then 450m high (1500 feet)

composite/stratovolcanoes

built up from multiple eruptions, form cones with steep sides, located in mainly 2 chains (ring of fire and Mediterranean belt)

3 classifications of volcanoes

extinct, dormant, active

extinct

scientist consider volcano to unlikely erupt again, the volcano no longer has supply of magma (e.g. twin peaks-vancouver island)

dormant

referred to as "sleeping volcanoes", have not erupted for extensive periods of time (e.g. Mt. Kilimanjaro)

active

considered to be erupting or will be erupting (e.g. Mt. Etna in Sicily)

how do volcanoes affect the world/ring of fire

they create new land and habitats while also destroying many

volcanoes in canada

found mainly in western Canada (BC and Yukon)

earthquake cause

two plates move sideways past each other and a lot of energy gets released

earthquake consequences

shaky ground which destroys land, homes and etc.

how earthquakes are measured

Richter scale/moment magnitude

how is canada impacted by earthquakes

through the west coast (BC) because of the most seismic activity and lies along tectonic plate boundaries

how do we prepare for earthquakes

*Earthquake hazard and Risk assessment

*Better houses with appropriate materials

tsunamis

giant waves produced by major tectonic events on the sea floor

tsunami stage 1 (generation)

results when there is a seafloor disturbance such as movement along a faut line

tsunami stage 2 (propagation)

as water depth increases and as wavelength increases, the speed will also increase, feature on the floor can deflect the wave which will send it in different directions

tsunami stage 3 (shoaling)

water at the front of the wave reaches the shoreline, water slows down because the shallower water creates drag on the wave

tsunami stage 4 (inundation)

occurs when the wave breaks, waves often travel far inland and suck people out to sea as the water recedes

are tsunamis preventable

no but early warning and education are key

canadas greatest tsunami

newfoundland 1929

most prone part of canada to a tsunami

BC as it has the greatest number of earthquakes