unit 1 - plate tectonics

close land fit between the coastlines of the continents

coastlines fit together like puzzle pieces

south america fits really well into africa

close geological correlation across landmasses

shield and non-shield areas align, mountain ranges fit into mountain ranges

study of past climates show that certain areas had the same climatological history that would only be possible had they been attached/in the same location

some of the strongest evidence

continental glaciation that correlated between land masses would have been impossible unless these continents were once united

fossil remains of pre-mesozoic life are uniform and correlate between the southern continents

would be impossible for these plants and animals to have crossed the oceans as they are today

within ocean basins where molten magma is extruded, there is evidence of plate movement as the magma shows signs of reversal of magnetic polarity over time

in the ocean basin, the molten magma is thrusting through the earth, north is true north, but over time true north reverses

diverging, converging, and transforming

moving away from each other

forms new lithosphere and is the youngest land on earth

creates mid-ocean ridges or rift zones (ex. east african rift valley)

seafloor spreading can lead to mid-ocean ridges

moving together

when 2 plates are moving towards each other, 1 plate will eventually be pushed down under the other plate due to variations in density

2 continental plates converge: may form mountains

continental plate and oceanic plate converge: oceanic plate will subduct and create a trench

2 oceanic plates converge: process is longer, eventually one will begin to descend and be reclaimed by the mantle (may form a string of volcanic islands)

where the lithospheric crust is being pushed under and reclaimed by the mantle (where the oldest rock material is found)

occurs when an oceanic and continental plate meet

occurs when 2 plates slide horizontally past each other

surface area is neither created or destroyed

known as a tear or strike-slip fault

great friction between the 2 plates, and if they become locked massive earthquakes can occur when the pressure releases

normal, reverse (compression), strike-slip, horst, graben

plates move away from each other

one goes up, one goes down

plates converge, one goes up, one goes down

transform boundary

block mountain, occurs under tension

like a horse, you can mount it

rift valley, also created under tension

looks like someone grabbed chunks out of it

sedimentary, metamorphic, igneous

formed from layers of sand, silt, dead plants, and animal skeletons, mainly found in watery areas ex. sandstone

formed from other rocks that are changed by heat and pressure underground, found in mountainous regions ex. marble, quartz, slate

formed from melted rock deep inside the earth, found in volcanic regions ex. gabbro, basalt (in oceanic crust), granite, andesite (continental crust)

cinder cone, shield cone, composite cone

predominantly found on continents

made up of acidic lava

made of layers of cinder and ash

compact/small in size

highly violent and explosive

associated with pyroclastic flows

fast cooling = can cause clogged neck ex. Mt. Fuji

large and gentle sloping

basic lava (basaltic lava) = wet like concrete

do not violently erupt, instead ooze -> any accounts of violent eruption tend to be from steam as the lava comes in contact with the water

cools very slowly and spreads over large areas

predominantly found on ocean floors ex. Hawaiian Islands

most often formed over subduction zones (Pacific Ring of Fire)

symmetrical formation with cake-like layers of lava and ash

snow and ice-capped

more moderately sloped than cinder cones

tend to be larger in size

sudden and violent eruptions ex. Pacific Ring of Fire

juicy crack

more associated w/ oceanic crust and occur when magma flows up through cracks in the crust and "erupts"

an area on the earth's mantle where magma rises up to melt through the crust, creating volcanoes or volcanic islands

lava flows, tephra flows, pyroclastic flows, mudflows

pour or ooze out of vents or cracks

causes majority of harm to non-moveable objects (trees, cars)

basaltic lava can travel vast distances vs. andesite lava that rarely goes past ~8 km.

objects and terrain are either surrounded, buried or ignited

made up of cinder and ash (super concentrated)

majority of fragments fall back onto the slope, enlarging it

alters climate

hot and dry rocks, gases and lava pieces

fast-moving and dense <- 200m/s (like an avalanche in this sense)

will burn anything in its path

considered the most deadly of hazards (another name for the deadly gases and debris is nuees ardentes)

same consistency as cement

happens when the steam, heat or lava from the volcano melt the snow-capped tops and ice, and that watery runoff mixes with ash, debris and dirt to create a mudflow

creates igneous rocks that can be used as building materials

creates fertile soil

a source of geothermal energy

tourism! (slay)

destructive

can cause lots of air pollution b/c of the ash (like Mt. St. Helens)

can have many casualties if they erupt aggressively and without fair warning

gas will kill you

forms because the magma chamber empties/oozes out so fast that the volcanoes lose their structural integrity

also forms because the explosion is so violent that the volcano blows its top off

largest feature, looks like a giant pool of magma underground

2nd largest feature

found between layers

usually dome-shaped but smaller

cuts through multiple layers (across)

stuck between layers

cuts in between layers

when stress-deformed rocks break or release pressure by elastic rebound or sudden shift in position and severe shaking of the ground may occur

lasts ~10-30 s

body waves and surface waves

primary waves, secondary waves, surface waves

aka compression wave

a type of body wave (much smaller)

travels by compressing and expanding the ground

the fastest

first to reach the earthquake recording stations

aka shear wave

second wave generated by quakes

slower than the primary waves and travels in a side-to-side motion

more extreme + aggressive

travels like ripples through calm water

responsible for ground shaking which causes much of the damage during earthquakes

includes love waves (move back + forth) and Rayleigh waves (rolling)

smaller earthquake that follows a larger earthquake

occurs in the same area of the crust/fault

the location where the fracture/shift occurs and the seismic waves originate

depth varies but can be as deep as ~700km

located on the surface of the earth directly above the focus point

a series of waves caused by the displacement of water from an earthquake

a measure of the size/amplitude of the seismic waves generated by an earthquake

recorded by seismographs

goes from 1 to 8.9

each number is 10x stronger than the previous

usually a tremor less than 3 will not be felt

a 6.5 and above will cause extensive damage