ENV Geography - Exam 2: Tectonics and Geography

verticality and temp

temperature decreases

verticality and atmospheric pressure

atmospheric pressure decreases

verticality and precipitaion

precipitation increases on windward side

converging boundaries

two plates moving towards each other

subduction

denser plate goes under the less dense plate when converging

plate density

oceanic plate is denser than continental plate

continental plate (mafic or felsic)

felsic - formed from slow flowing magma / often explosive eruption

oceanic plate (mafic or felsic)

Mafic - form from high temperature magma and form dark colored igneous rock

why do oceanic plate subductions cause volcanoes

oceanic plate is composed of volatiles and as it heats it melts and rises, breaking through the surface

subduction range is (blank) and creates (blank)

volcanic/oceanic trenches

Example of converging subduction boundaries

Mount Rainer and Cascades

Mount Rainer and Cascades was formed from

collision of North America and Juan de fuca plate

what is happening at the cascade volcanic arc

the juan de fuca and north american plates are converging

U.S coastal range was fromed for 3 reasons

1. folded regions of seaward volcanoes

2. accretionary wedges: scraped from subducting slab

3. Exotic terranes: islands

Converging: Continent to continent

plates are the same density so collision creates mountains/more earthquakes with this collision type

Appalachians and Caledonia

Formed together during pangea dues to continent - continent collisions

Fault boundaries

transform fauls can cause localized extension and compression

hanging wall falls during (blank) fault

normal/extension

hanging wall goes up during (blank)

reverse/compression

shallow focus

when earthquake is close to the surface

remnants of the farallon plate

Juan de fuca and Cocos plates

what happened to Farallon plate

most of it is under the North American Plate

Sierra Nevada range was created from

extension, denudation, and differential weathering

denudation

lowering of a landscape

differential weathering

different types of rock weather at different rates

sierra nevada is a

tilted fault block/footwall is up

horst and grobin

Range and Basin

elastic

moves and snaps back into place

plastic

moves and stays in place

brittle

moves and breaks

Mountains from Dissection

Colombia flood basalts

Colombia flood basalt formation

caused by fisher eruptions (spilling out of magma), 6000 thick magma flows that created flat tops, then water dissected the old magma

rocky mountain formation

shallow subduction of the farallon plate under the NA plate, pushed up granite and metamorphic rocks from the core. Erosional resistence supports the high peaks

volcanic

crystalizes above surface

plutonic

crystalizes below surface

Pennsylvanian 320 mya

uplift of the ancestral mountains

fountain formation

pieces of the ancestral rockies deposited during the pennsylvanian (red rocks, garden of the gods, flatirons)

Cretaceous sea 130 mya

sandstone