Geo Exam 2

what is the driving force of orogenesis

subduction

oceanic lithosphere descends and is reabsorbed into mantle

Convergent boundaries

What is the evidence in support of the plate tectonic theory?

age and thickness of seafloor sediment, hot-spot tracks, magnetic reversals and seafloor spreading

neither plate subducts during _____collisions

continent-continent

occurs when divergent boundaries develop within a continent

continental rifting

Alternating symmetrical bands of opposite polarity in oceanic crust are produced at a mid-oceanic ridge. How can this be explained? a. the rate of spreading changes over time b. the magma produced changes composition c. there are different types of volcanoes producing the magma d. the iron-rich minerals in the magma align with the existing magnetic field of Earth as they crystallize e. the plates are alternately moving north and south at different times

d

New oceanic crust is created at divergent boundaries at a rate of about a. 5 meters/year b. 5 kilometers/year c. 5 centimeters/century d. 5 centimeters/year

d

Plate tectonics and plume generation are thought to be ultimately drive by _____ a. slab push b. radiation c. conduction d. convection

d

Very fine-grained material ejected by a volcano that can drift in air very long distances is called: a. lahar b. pyroclastic flow c. viscosity d. ash

d

Which of the following has provided the best means for us to learn about the layered structure of Earth? a. x-rays of the interior b. infrared technology c. locations of volcanic activity d. study of seismic waves

d

_____is how thick or thin a liquid is, or its resistance to flowing a. permeability b. lahar c. porosity d. viscosity

d

all changes in shape, position, or orientation of a rock mass

deformation

form where streams enter still bodies of water

deltas

how do streams deposit?

deposit sorted sediment when they reach critical settling velocity

the volume of water flowing past a certain point in a given unit of time

discharge

how are seismographs used to locate an earthquake epicenter?

distance between the first p wave and the first s wave

change in the size and shape of a rock that occurs at depth

ductile formation

A magma's viscosity is directly related to its temperature and ____ a. depth b. color c. age d. volcanic cone e. silica content

e

What general statement can be made about the distribution of earthquake epicenters on the earth? a. Earthquakes happen only in the middle of the ocean basin b. Most strong earthquakes are concentrated around the Atlantic Ocean c. Earthquakes occur only along the margins of the continents d. Most earthquakes happen within the interior of continents e. Most earthquakes occur along plate boundaries

e

the sudden movement of one block of rock slipping past another along a fault

earthquake

causes deformed rock to spring back to undeformed position

elastic rebound

earth's surface directly above the hypocenter

epicenter

seismic waves radiate our from the ___

focus

how do levees form?

form when coarse sediment is deposited in thin strips parallel to channels during flooding

how do deltas form?

form when streams enter a standing body of water

linear breaks in the seafloor are ____

fracture zones

the vertical drop over a specified distance

gradient

Mount Rainer in Washington State is considered a dangerous volcano because the thick glacial ice that sits atop the volcano could generate a____

lahar

water-saturated pyroclastic materials move down steep volcanic slopes

lahars

erupted magma

lava

stable soil becomes mobile and raises to the surface

liquefaction

stiff top of upper mantle plus crust

lithosphere

molten rock containing crystals and dissolved gas

magma

a quantitative measure of energy released in an earthquake

magnitude

What are the primary driving forces of plate motion?

mantle convective flow

measures total energy released based on amount of slide, area of rupture, and strength of faulted rock

moment magnitude

built by successive floods on rivers in broad floodplains

natural levees

cold, dense oceanic crust sinks beacause it is denser than the asthenosphere

slab pull

most volcanoes are found near____

the Pacific ocean and mid-ocean ridges

resistance to flow

viscosity

upwelling of hot material form mantle creates new seafloor

Divergent boundaries

intensity measures the amount of ground shaking based on property damage

Modified Mercalli Intensity Scale

What is the mechanism that generates large earthquakes?

Redi's elastic rebound theory

related to amplitude of the largest seismic wave

Richter scale

temperature, composition, and amount of dissolved gas affect magma behavior

The Nature of Volcanic Eruptions

two plates slide past each other

Transform boudnaries

During oceanic-continental convergence, a deep-ocean______is often produced adjacent to the zone of subduction as the oceanic plate slides beneath the overriding plate a. trench b. mountain range c. rift valley

a

In areas where unconsolidated material are saturated with water, earthquakes can turn stable soil into a fluid during a phenomenon called_____ a. liquefaction b. localization c. leaching d. lithification

a

The Richter Magnitude scale is based upon: a. the amount of energy released as recorded by the larges amplitude of the shear waves b. observations of the severity of shaking and damage caused c. the amount and length of earth surface rupture and the strengths of rocks involved d. the depth of an earthquake

a

The liquid composition of Earth's outer core was determined by the____ a. presence of a large S wave shadow zone b. presence of a large P wave shadow zone c. occurrence of a widespread volcanic activity d. the wobble of the Earth as it rotates

a

What is the main factor that triggers formation of magma when a cold slab of oceanic lithosphere is subducted? a. the subducting slab supplies water to a wedge of hot mantle rock thereby lowering its melting temperature b. the subducting slab carries sediment deep into Earth where it melts c. friction between the subducting slab and the mantle rock generates enough heat to trigger melting d. the subducting plate displaces hot mantle rock which rises to form magma

a

how can floods be controlled?

artifical levees, flood control dams, channelization

weaker portion below the lithosphere

asthenosphere

According to the theory of plate tectonics, tectonic plates interact mainly a. on the underside of each plate b. along plate boundaries c. near the center of each plate where stress is greatest d. scientists don't know for sure

b

At convergent plate boundaries a. new lithosphere is forming b. old lithosphere is being destroyed c. neither a or b d. both a and b

b

Complex mountain systems such as the Alps, Appalachians, and Himalayas are generally formed at a: a. divergent boundary b. convergent boundary c. transform boundary d. hotspot e. none of these answers are correct

b

Which of the following statements most accurately describes the volcanoes of the Hawaiian islands a. they occur along a mid-Pacific transform fault b. they are fed by a long-lived hot spot deep below the Pacific lithospheric plate c. they are associated with a mid-Pacific ocean ridge and seafloor spreading d. they are associated with subduction and convergent plate boundaries e. they are forming along an island arc

b

deposits of sand and gravel

bars

waves that travel through Earth's interior

body waves

fracturing of rock when elastic limit of a rock is surpassed that occurs at or near the surface

brittle deformation

how do streams erode?

by dislodging and lifting material from the channel or by abrasion

Earth's rigid outer layer overlies a zone of weaker and hotter material known as the: a. mesosphere b. cryosphere c. asthenosphere d. lithosphere

c

Why was Alfred Wegener's hypotheses of continental drift not taken seriously by most geologists? a. his evidence for former joining of the continents was faulty b. because it was and is known that continents do not move c. he did not have a good mechanism for explaining continental drift d. he was not a well-respected sceintist

c

an area of volcanism, high heat flow, and crustal uplift above a mantle plume

hot spot

forms as the Pacific Plate moved over the hot spot

hot-spot track

one slab subducts under another at ____boundaries

oceanic-oceanic convergent

the set of processes that forms a mountain belt

orogenesis

Why is earth layered?

physical and chemical segregation of molten material when earth formed

hot volcanic gas infused in incandescent ash and lava fragments, caused by collapse of eruption columns

pyroclastic flow

how are seismic waves used to describe earths interior

reflection, refraction and velocity are used to interpret composition and temperature of a rock

a deep canyon along the crest of a ridge resulting from tensional forces

rift valley

the process by which new seafloor is created along the ocean ridge system

seafloor spreading

oceanic lithosphere+continental lithosphere=

subduction of oceanic lithosphere

the hydrolgic cycle is powered by the____

sun

waves that travel in rock layers just below Earth's surface

surface waves

_____forms when two plates slide horizontally past one another

transform plate boundaries

how do streams transport?

transport sediment as dissolved load, suspended load or bedload

what causes floods?

when discharge exceed channel capacity