Geo - chapter 14 (Internal Processes)

A volcanic mudflow is known as a(n) ________

lahar

the sudden rupture and displacement along a fault cause most ____________.

large earthquakes

Currently, the rate of sea-floor spreading in the Atlantic is thought to be

less than 1 centimeter per year

Mt. St. Helen's is ________.

likely to vigorously erupt again

even though each earthquake can be assigned a single magnitude number to describe its relative size, every earthquake generates a wide range of ___________.

local ground shaking intensities.

divergent boundary

magma from the asthenosphere rises up b/w two plates, and this upward flow of molten material produces a line of volcanic vents that spill out basaltic lava onto the ocean floor, with the platonic rock gabbro solidifying deeper below

what landform is a representation of a divergent boundary?

mid ocean ridge

A ________ is a one-sided fold connecting horizontal or gently inclined strate.

monocline

is faulting slow?

movement of crust along a fault zone can be very slow, but it commonly occurs as a sudden rupture

what type of faulting is most commonly associated with fault scarps?

normal faulting (a vertically displacement)

types of faults

normal faults reverse fault thrust fault strike-slip fault

paleomagnetism

orientation that becomes a permanent record of the polarity of Earth's magnetic field at the time the rock is solidified. - when any rock containing iron - such as iron-rich ocean floor basalt- forms, it is magnetized such that the magnetic field within its iron-rich grains become aligned with Earth's magnetic field

evidence to seafloor spreading

paleomagnetism ocean floor cores

convergent boundary

plates collisions that are "destructive" and responsible for landforms such as, major mountain ranges, volcanoes, ocean trenches

Volcanic activity that takes place deep under the crust is termed ________.

plutonic

subduction

process whereby older lithosphere descends into the asthenosphere.

The totality of materials ejected from a volcano, including liquid material, ashes and dust is termed ________.

pyroclastic material

overthrust fold

results if pressure is enough to break an overturned fold and cause a shearing movement, and older rock rides above younger rock.

A lengthy complex of grabens forms a ________ valley.

rift

Water collected in small bodies along a recently active fault line forms ________.

sag ponds

ocean floor cores

sea-bottom sediments show that thickness of sediment and the age of fossils increase with increasing distance from the mid ocean ridges - indicates sediments farthest from ridges are oldest

what theory proposed in the 1960s provided evidence for WEgner's continental drift?

seafloor spreading

what scale measured the magnitude of an earthquake?

the Richter scale

how is lithosphere recycled through subduction?

the amount of new seafloor created at mid ocean ridges is compensated for by the amount lost at trenches, which are part of subduction zones.

Both P and S waves travel through.....

the body of Earth - they're body waves

folding

the deformation or bending of crustal rocks due to their being subjected to stress, particularly lateral compression.

where are the strongest shocks, and greatest crustal vibration of an earthquake felt?

the epicenter - the ground directly above the focus

describe the differences b/w an oceanic trench and a mid ocean ridge

the first is a result of subduction w/ the convergence of an oceanic plate. the second is a representation of a divergent boundary involving seafloor spreading

folds are generally classified according to____________________

the orientation of the bend.

epicenter

the point on Earth's surface that lies directly above the focus

Relatively cooler magma in an erupting volcano is apparently the result of ________.

the relatively high amount of silica present

Focus

the subsurface location where an earthquake originates. -- where seismic waves originate at he center of fault motion

seafloor spreading

theory that stated that mid ocean ridges are formed by currents of magma rising up from the mantle and that volcanic eruptions create new basaltic ocean floor, which then spreads away laterally from the ridge

A ________ plate boundary is associated with lateral slippage, conservation of existing crust, and the San Andreas fault system?

transform

A foreshock sometimes comes before a major earthquake True or false?

true

A simple symmetrical upfold in topography is an anticline. True or false?

true

Deep fault zones apparently serve as conduits allowing water and heat to approach the surface.

true

In the Cascade Range, there are many peaks larger or taller than Mount Saint Helens which exploded.

true

The Andesite Line refers to the numerous volcanoes which dot the rim of the Pacific Ocean. true or false?

true

The Earth's crust is rigid as compared to the mantle directly underneath.

true

The largest recorded earthquake had a moment magnitude of 9.5 and occurred in Chile. True or false?

true

The southern portion of the "super continent" envisioned by Wegener is called Gondwanaland.

true

faulting

when a rock structure is broken and one side is forcibly displaced relative to the other

describe the age pattern of the ocean floors. How does this pattern help verify seafloor spreading?

youngest at ridges and other in directions away from ridges

Which is older: continental crust or oceanic crust?

continental crust b/c since it is less dense and cannot be subducted, the interiors of continents have a "core" and are permanent - 20 times the age of oceanic crust which is on average 100 million years

________ is an area of extensive flood basalts.

The Columbia Plateau The Deccan Plateau

On the Modified Mercalli scale, the largest earthquakes would be assigned a value of ________.

XII

is folding over a long period of time?

Yes when great pressure (and sometimes heat) is applied for long periods - specially deep below the surface - the result is often a slow plastic deformation that can produce folded structures fo incredible complexity.

can folding occur in any kind of rock?

Yes - BUT it is most recognizable when once - flat sedimentary strata have been deformed

Crater Lake, Oregon, is an example of a volcanic ________.

caldera

characteristic of shield volcano?

composed of lavas and relatively little ash or cinders and gentle slopes

characteristic of composite cone?

consist of a mix of lava flows and pyroclastic materials

divergent boundaries can also develop within a continent, resulting in a _______________

continental Rift Valley

characteristic of plug domes (lava)?

extrude extremely stiff acidic lava that fills the initial pyroclasitc cone and steep sided

A fault is any break in the Earth's surface or crust.

false

Prior to Mt. St. Helens in 1980 there had never been an active volcano in the United States.

false

Lava flows often create _______.

flattish plains

what type of tectonics causes the Ridge- and- Valley section of the Appalachian Mountains?

folding

two types of tectonism

folding and faulting

A crustal block which is downthrown with a steep fault scarp on either side is a ________.

graben

what are tsunamis and their characteristics?

great seismic sea waves, which are sometimes generated by undersea fault ruptures or landslides - move sequentially across - barely perceptible in deep water

seiches

great waves set in motion in lakes and reservoirs by abrupt crustal movement - causes them to overflow shorelines or dams

Grabens are commonly found in association with ________.

horsts

overturned fold

if an uphold is pushed extensively from one side

The Alaskan earthquake of 1964 was extraordinarily violent and has been assigned a moment magnitude of ________.

9.2

In earthquakes, P waves________.

are faster than S waves

characteristics of surface waves

arrive after S waves and produces strong side to side movement as well as up and down rolling motion

Modified Mercalli Scale

assigns the strength of local shaking to 1 to 12 categories, based on the observed effects and damage

Presently, the North American and Eurasian plates are moving ________.

away from each other

The ________ is an igneous intrusion which has a surface area of at least 100 square kilometers.

batholith

The most massive form of igneous intrusion is a ________.

batholith

how are mid ocean ridges and continental rift valleys related?

both are types of divergent boundaries - spreading away from each other

Divergent boundaries are ____________ - material is being added to the crustal surface.

"constructive"

Wegener's evidence for continental drift

- continental margins fit - petrologic record - mountain belts - paleontology (fossils of dinosaurs and plants) - glacial deposits

characteristics of s or secondary waves

- follow the initial jolt of P waves and move side to side and up and down with sharing motion - they are slower

characteristics & landforms of a divergent boundary

- mid ocean ridge - spreading centers - shallow focus earthquakes - volcanic activity - hydrothermal metamorphism - as well as marine life thriving in the hostile environment of hydrothermal vents

how do seismologists pinpoint the focus of an earthquake with precision?

- seismographs - comparing arrival times of the seismic waves (P and S waves)

what are the rates of seafloor spreading in the Pacific-Antarctic Ridge?

10 centimeters

continental drift was revived by __________

Alfred Wegener

the difference between "folding" and "faulting?"

Folding is the wrinkling of the earth's surface from slow lateral compression Faulting is the rupture or breaking of the earth's surface from faster process.

what scale measured the intensity of an earthquake?

Modified Mercalli Scale

three types of convergent boundaries:

Oceanic-Continental Convergence. Oceanic-Oceanic Convergence. Continental-Continental Convergence.

the fast-moving seismic waves are.....

P or primary waves (the first)

four basic types of volcanoes?

Shield volcano composite cone plug dome (lava dome) Cinder cones

strike-slip fault

a fault in which the movement is horizontal (side to side), with the adjacent blocks being displaced laterally relative to teach other. - result from shear stresses (stress causing two parallel surfaces to slide past one another) - transform faults

thrust fault (overthrust fault)

a fault related to reverse faults, in which compression forces the upthrown block to override the downthrown block downthrown block at a relatively low angle. - frequently occurs mountain building -- unusual geologic relationships, such as older Strat being piled atop younger rocks

reverse fault

a fault that is produced from compression stresses (pushing together), where one block slides up the incline of fault plane

normal fault

a fault that results from tension stresses (pulling apart of extension) in the crust and produces a very steeply inclined fault zone, where one block slides down the fault plane ("normal" to the pull of gravity)

syncline

a simple downfold

anticline

a simple symmetrical uphold

earthquake

a vibration in Earth produced by shock waves resulting from a sudden displacement along a fault.

what is the driving mechanism for plate tectonics?

convection (brings deep, hot rock slowly to surface) - pushing of plates away from mid ocean ridges occurs to an extent, BUT that much of the motion is a result of the plates being "pulled" along by the. subduction of colder, denser oceanic lithosphere down into the asthenosphere

Tectonism (Diastrophism)

deformation of earth's crust

magnitude

describes the relative amount of energy released during an earthquake. - calculated on a logarithmic scale.

Radial walls extending outward from a volcano are ________.

dikes

liquefaction

during the shaking of an earthquake, loose, water saturated sediments, such as coastal landfill, may undergo ___________, that is, become fluid.

A(n) ________ is an abrupt movement of the Earth's crust usually associated with a fault zone.

earthquake

landslides are often triggered by ____________

earthquakes

characteristic of cinder cones?

smallest type, produces litle lava and consists largely of pyroclastics

the Rea Sea is the outcome of ____________ taking place within a continent, which resulted in forming a "proto-ocean"?

spreading - divergent boundary

fault scarps

steep cliffs that represent the edge of a vertically displaced block

Similar in nature to a batholith but much smaller in size is a ________. dike all of the above vein sill stock

stock

Instead of the vertical displacement of other faults, a ________ fault has horizontal displacement .between the two sides

strike-slip

both thrust and reverse faults are commonly associated with _______________or_________________

subduction zones or continental collision zones

what is the result of liquefaction?

subsidence, fracturing, and horizontal sliding of the surface

the third type of seismic wave is limited to the __________.

surface

what types of topography is most commonly associated with a syncline? An anticline?

syncline - valley anticline - ridge

why is it possible for anticlines to produces ridges and the downfolded cyclones to from valleys?

the "inverted" topography is explained by the effects of tension (pulling apart) and compression (pushing together) on the folded strata - where a layer is arched over an uphold, tension cracks can form and provide easy footholds for erosional processes to remove materials and inside downward into the underlying strata. ALSO- the compression that acts on the downfolded beds increases their density and therefore their resistance to erosion. THUS, over a long time, the upholds may be eroded faster than the downloads, producing anticlinal valleys and synclinal ridges.

anticlinal valleys and synclinal ridges ....

the "inverted" topography landforms related to the structures of folding, which are produced b/c of the increased erosion of a layer arched over an uphold and its tension cracks AND b/c of the compression, increased density, and resistance to erosion on a downfolded bed.