Study Guide [14<=>16<=>17<=>18]

The oceans contain about how much of the water in the hydrosphere? A. 96% B. 50% C. 80% D. 35%

96%

Significant increases in S-wave velocity at about 400 and 650 kilometers depth are explained by A. changes in the chemical composition of the mantle. B. a collapse of the crystal structures to more close by packed forms. C. changes in the degree of partial melting within the mantle. D. rapid increases in temperature.

A COLLAPSE OF THE CRYSTAL STRUCTURES TO MORE CLOSE BY PACKED FORMS

If a flood is classified as a fifty-year flood, A. it has been fifty years since the last flood that large occurred. B. a flood at least that large has occurred every year within the last fifty years. C. the flooded area is safe from a serious flood for at least fifty years. D. a flood that large occurs on the average of once every fifty years but also has a chance of occurring during any year.

A FLOOD THAT LARGE OCCURS ON THE AVERAGE OF ONCE EVERY 50 YEARS BUT ALSO HAS A CHANCE OF OCCURRING DURING ANY YEAR

Homeowners in California whose houses survived recent wildfires are not quite out of the woods yet. With the approaching rainy season their next problem will be A. increased potential for mudflows and debris flows. B. accelerated soil erosion. C. flash floods. D. all of the above.

ALL OF THE ABOVE

The Earth's core is inferred to be composed of mostly iron because A. iron is naturally very abundant. B. most meteorites representing the interstellar matter from which the planets formed are rich in iron. C. iron is very dense, so its presence in the core would account for the Earth's average density. D. all of the above.

ALL OF THE ABOVE

What stream feature(s) can develop as a result of regional uplift and erosion? A. accelerated downcutting in steams B. stream terraces C. incised meanders D. all of the above

ALL OF THE ABOVE

Active erosion in a meander bend takes place A. in the center of the stream. B. along the outer bank of a bend. C. along the inside bank of a bend. D. near a stream's headwaters.

ALONG THE OUTER BANK OF A BEND

An aquiclude is A. a confined aquifer. B. always located at the top of the water table. C. a rock layer that provides a good flow of water into a well. D. an impermeable rock layer that does not allow water to flow through it.

AN IMPERMEABLE ROCK LAYER THAT DOES NOT ALLOW WATER TO FLOW THROUGH IT

A rock or soil layer that is water-bearing is a(n) A. perched water table. B. stratum. C. zone of aeration. D. aquifer.

AQUIFER

The thickness of Earth's tectonic plates is A. the same on the continents as under the oceans. B. at its thinnest under the oceans. C. at its thinnest in the continents. D. completely unknown.

AT ITS THINNEST UNDER THE OCEANS

Earth's tectonic plates are located in the A. core, where their movement is driven by intense heat and pressure. B. mantle, where their movement is driven by convection. C. lithosphere, where their movement is driven by gravity. D. atmosphere, where their movement is driven by the prevailing westerlies.

ATMOSPHERE, WHERE THEIR MOVEMENT IS DRIVEN BY THE PREVAILING WESTERLIES

Although water is an important agent of chemical weathering in its own right, it becomes more effective if small amounts of carbonic acid are present. Carbonic acid is formed when A. carbon from coal beds or from graphite deposits is pulverized along a fault or fracture and then added to water. B. carbon dioxide from the atmosphere or from organic decomposition is added to water. C. sulfur from coal-fired power plants is added to water. D. water comes in contact with the calcite in a limestone layer.

CARBON DIOXIDE FROM THE ATMOSPHERE OR FROM ORGANIC DECOMPOSITION IS ADDED TO WATER

Entrenched meanders like the San Juan River are evidence of a A. decrease in stream gradient. B. decrease in discharge. C. change such that the river has renewed ability to erode. D. decrease in stream velocity.

CHANGE SUCH THAT THE RIVER HAS RENEWED ABILITY TO ERODE

Clay minerals, like kaolinite, are a product of ______ weathering of ______ minerals and are a raw material for ______. A. chemical / silicate / pottery B. chemical / sulfide / asphalt C. physical / sulfate / cement D. physical / carbonate / fertilizers

CHEMICAL/SILICATE/POTTERY

Talus consists largely of A. clay and other very fine rock particles. B. a mixture of powdered rock and ice. C. coarse, angular rock fragments. D. alternate layers of sand, silt, and clay.

COARSE, ANGULAR ROCK FRAGMENTS

Solifluction usually occurs in A. cold regions. B. very cold regions like Antarctica. C. any area where there is a lot of sunshine. D. tropical regions.

COLD REGIONS

As the lithosphere cools slowly by the conduction of heat, it becomes A. less dense and rises. B. soft and weak. C. denser and rises. D. denser and subsides.

DENSER AND SUBSIDES

The regular dumping of crushed rock and coal waste into a stream leads to A. erosion upstream and deposition downstream from the dump. B. erosion both upstream and downstream from the dump. C. deposition both upstream and downstream from the dump. D. deposition upstream and erosion downstream from the dump.

DEPOSITION BOTH UPSTREAM AND DOWNSTREAM FROM THE DUMP

The volume of water that flows past a given point along a stream channel in a given interval of time is the A. velocity. B. discharge. C. capacity. D. gradient.

DISCHARGE

If flood control engineers straighten out a meandering stream channel, the stream probably A. flows more slowly in the straightened stretch. B. deposits in the straightened stretch. C. downcuts in the straightened stretch. D. downcuts and flows more rapidly in the straightened stretch.

DOWNCUTS AND FLOWS MORE RAPIDLY IN THE STRAIGHTENED

Which of the following options is the most effective way to stabilize an active landslide? A. piling additional rock and soil material on the landslide near its top B. saturating the landslide itself with water C. draining the water away from and out of the landslide area D. cutting away the toe (base) of the landslide

DRAINING THE WATER AWAY FROM AND OUT OF THE LANDSLIDE AREA

Of the following agents, which is NOT involved in the process of chemical weathering? A. water B. carbon dioxide C. oxygen D. nitrogen

NITROGEN

The inference that Earth's outer core is liquid is supported by the observation that A. P waves do not pass through it. B. S waves do not pass through it. C. P waves travel more rapidly through it. D. S waves travel more slowly through it.

S-WAVE DO NOT PASS THROUGH IT

A perched water table will most likely develop on top of A. shale. B. gravel. C. highly fractured granite. D. sandstone.

SHALE

Which of the following would be most subject to mass movements (assuming slope and climate are the same in each case)? A. high-grade gneiss, with highly contorted foliation B. quartz-cemented sandstone, with layering perpendicular to the slope C. shale, with bedding parallel to the slope D. massive granite bedrock

SHALE, WITH BEDDING PARALLEL TO THE SLOPE

Without any knowledge of what seismic waves tell us about the Earth's interior, why is it unreasonable to assume that a large portion of the lower mantle is molten? A. Actually, it could be molten. We just don't see evidence for it because silicate magmas are trapped within the Earth due to the confining pressures. B. Direct measurements show that the temperature at the core/mantle boundary is not high enough to melt the lower mantle. C. The magnetic field strength would be greatly reduced if more of the Earth's interior was molten. D. Silicate magmas are less dense and would rise to the surface, so we should observe widespread volcanic activity across the Earth's surface. The molten iron-rich outer core is too dense to rise.

SILICATE MAGMAS ARE LESS DENSE AND WOULD RISE TO THE SURFACE, SO WE SHOULD OBSERVE WIDESPREAD VOLCANIC ACTIVITY ACROSS THE EARTH'S SURFACE. THE MOLTEN IRON-RICH OUTER CORE IS TOO DENSE TO RISE

Mass wasting tends to occur when A. a slope becomes steeper due to undercutting by a river or ocean waves. B. the mass on a slope decreases by draining water from the ground. C. friction is increased by draining water from the ground. D. friction is decreased by taking water out of the ground.

SLOPE BECOMES STEEPER DUE TO UNDERCUTTING BY A RIVER OR OCEAN WAVES

Rivers and streams that flow all year long, even during long periods without rain, are probably fed by A. sinkholes. B. wells. C. springs. D. karst conditions.

SPRINGS

An iciclelike deposit hanging from the ceiling of a cave is a A. stalactite. B. stalagmite. C. karst formation. D. quartzite.

STALACTITE

Stream velocity generally increases downstream even though stream gradient decreases because A. the river channel typically becomes rougher downstream. B. channels typically meander less downstream. C. the amount of sediment decreases downstream. D. stream discharge typically increases downstream as tributaries contribute their water.

STREAM DISCHARGE TYPICALLY INCREASES DOWNSTREAM AS TRIBUTARIES CONTRIBUTE THEIR WATER

Where streams emerge from a narrow mountain canyon onto a flat plain, alluvial fans form because A. the increase in the amount of water from tributary canyons results in deposition. B. stream velocity decreases due to a widening of the stream channel and a decrease in gradient. C. stream velocity increases due to a decrease in gradient. D. all of the above.

STREAM VELOCITY DECREASES DUE TO A WIDENING OF THE STREAM CHANNEL AND A DECREASE IN GRADIENT

The Moho, or Mohorovicic discontinuity between the crust and the mantle, was first detected from A. the abrupt decrease in seismic velocities as they cross the discontinuity. B. the abrupt increase in seismic velocities as they cross the discontinuity. C. the S-wave shadow zone through which S waves do not pass. D. the observation that no earthquakes occur below the Moho.

THE ABRUPT INCREASE IN SEISMIC VELOCITIES AS THEY CROSS THE DISCONTINUITY

The highest density component of the Earth is A. the mantle. B. the core. C. continental crust. D. the whole Earth.

THE CORE

In the hydrologic cycle, how does the evaporation rate from the land surface compare with the evaporation rate from the oceans? A. The evaporation rate is much greater from the land than from the oceans. B. The evaporation rate is much greater from the oceans than from the land. C. Evaporation rates from the land and oceans are equal. D. There is no reasonable comparison because it is too wet over the oceans for evaporation to occur.

THE EVAPORATION RATE IS MUCH GREATER FROM THE OCEANS THAN FROM THE LAND

When a reversal of the Earth's magnetic field occurs, A. the sense of rotation of the Earth is also reversed. B. the Earth flips over in its orbit. C. the magnetic polarity of the Earth reverses so that the north end of a magnetic compass needle points toward the south geographic pole. D. almost all the igneous sedimentary rocks of the ocean floor reverses in magnetization to match the new orientation of the magnetic field.

THE MAGNETIC POLARITY OF THE EARTH REVERSES SO THAT THE NORTH END OF MAGNETIC COMPASS NEEDLE POINTS TOWARD THE SOUTH GEOGRAPHIC ROLE

If the regional base level of a stream is lowered, A. the stream will deposit to raise the base level to its former position. B. the stream will begin to downcut at its headwaters. C. the stream will begin to downcut at its downstream end, and downcutting will progress upstream until the stream channel is graded with the new base level. D. it will have no effect on the stream.

THE STREAM WILL BEGIN TO DOWNCUT AS ITS DOWNSTREAM END, AND DOWNCUTTING WILL PROGRESS UPSTREAM UNTIL THE STREAM CHANNEL IS GRADED WITH THE NEW BASE LEVEL

The potential for chemical weathering can be greatly enhanced by physical weathering because physical weathering increases A. the surface area of the rock particles. B. the availability of chemical agents. C. drainage and thereby reduces contact with water. D. the size of the rock particles.

THE SURFACE AREA OF THE ROCK PARTICLES

The water table is A. the top of the unsaturated zone. B. the top of the saturated zone. C. generally present only in moist climates. D. the contact between an aquifer and an underlying, impermeable layer of rock.

THE TOP OF THE SATURATED ZONE

If all other conditions are equal, groundwater moves faster A. where sand grains are very well cemented. B. through loose sand than through clay. C. where permeability of the aquifer is lower. D. through clay than through sand.

THROUGH LOOSE SAND THAN THROUGH CLAY

Supporting evidence for heat transfer by convection within the mantle comes from A. tomography and Earth's gravity field. B. the bulk density of the Earth. C. postglacial isostatic rebound. D. Earth's magnet field.

TOMOGRAPHY AND EARTH'S GRAVITY FIELD

An artesian well will flow if the A. top of the well is lower than the water table in the recharge area. B. top of the well is higher than the water table in the recharge area. C. bottom of the well is lower than the land surface in the recharge area. D. bottom of the well is lower than the water table in the recharge area.

TOP OF THE WELL IS LOWER THAN THE WATER TABLE IN THE RECHARGE AREA

As rocks experience increased pressure with depth, P waves in general will _______ as they migrate through them. A. travel faster B. travel slower C. travel at the same velocity D. rapidly die out

TRAVEL FASTER

Soil production is often described as a "positive feedback" process. Why? A. Carbon dioxide in rainwater is used up by organisms, so weathering of underlying rock is impeded. B. Rainwater becomes more acidic as it percolates through the soil, so weathering of underlying rock is promoted. C. Once a layer of soil is formed, the underlying rock is protected from further weathering. D. Plant growth reduces the potential for weathering and therefore of soil development.

RAINWATER BECOMES MORE ACIDIC AS IT PERCOLATES THROUGH THE SOIL, SO WEATHERING OF UNDERLYING ROCK IS PROMOTED

The P-wave shadow zone is caused by the way the Earth's core A. refracts the seismic waves. B. reflects the seismic waves. C. absorbs the P waves. D. blocks the P waves.

REFRACTS THE SEISMIC WAVES

The lithosphere is a __________ layer, as opposed to the asthenosphere. A. plastic B. weak C. fluid D. rigid

RIGID

Roads through mountainous regions tend to be unstable and require more maintenance if they are built on A. bedrock such as granite. B. horizontal lava flows. C. rock layers that dip perpendicular to the hillslope. D. rock layers that dip parallel to the hillslope.

ROCK LAYERS THAT DIP PARALLEL TO THE HILLSLOPE

An important factor in mass wasting is the orientation of rock layers, foliation, or jointing. For layered sedimentary and volcanic rocks, which condition is the least stable? A. Rock layers are at right angles to the slope. B. Rock layers are parallel to the slope. C. Rock layers are horizontal to the slope. D. Rock layers stand vertical.

ROCKS LAYERS ARE PARALLEL TO THE SLOPE

An example of chemical weathering is A. rusty streaks on a rock wall. B. angular blocks of rock rubble in the mountains. C. potholes in pavement. D. rocks wedged apart by tree roots.

RUSTY STREAKS ON A ROCK WALL

What happens to the porosity as the grain size gets smaller? A. It increases. B. It decreases. C. It remains unchanged. D. none of the above

IT DECREASES

Physical and chemical weathering in the warm, wet climates of the Earth's surface alter exposed granite to A. quartz and feldspar sand. B. iron-rich soil. C. olivine sand. D. quartz sand and clay.

QUARTZ SAND AND CLAY

Earth's core has a radius that is about __________ of the Earth's radius. A. 1/8 B. 1/2 C. 1/4 D. 3/4

1/2

You are canoeing a river in remote Alaska and your GPS shows an elevation of 2500 feet. After paddling for five days, you calculate that you have traveled 200 miles. Your GPS now shows an elevation of 2300 feet. What is the stream's gradient in feet/mile for the stretch you just canoed? A. 1 foot/mile B. 5 feet/mile C. 2 feet/mile D. 10 feet/mile

1 FOOT/MILE

Earth's north magnetic pole is located A. at the north geographic pole. B. in Alaska. C. between Greenland and Baffin Island. D. in China.

BETWEEN GREENLAND AND BAFFIN

The Earth's magnetic field is thought to be generated by A. permanent magnetism of minerals within the mantle. B. permanent magnetism of the solid iron-rich inner core. C. electrical currents generated by movement of the liquid outer core. D. electrical currents generated by convection in the asthenosphere

ELECTRICAL CURRENTS GENERATED BY MOVEMENT OF THE LIQUID OUTER CORE

If a dam is placed across a stream that has been carrying a large volume of sediment, the stream would probably A. deposit downstream and erode upstream from the dam. B. erode downstream and not change upstream from the dam. C. erode downstream and gradually deposit upstream from the dam. D. not change downstream but deposit upstream from the dam.

ERODE DOWNSTREAM AND GRADUALLY DEPOSIT UPSTREAM FROM THE DAM

The "Cretaceous quiet zone" is a name for a(n) A. period when dinosaurs were very sedate. B. time when plate motions slowed way down. C. break in volcanic activity on Earth due to a lack of mantle superplume activity. D. especially long period of normal polarity of Earth's magnetic field.

ESPECIALLY LONG PERIOD OF NORMAL POLARITY OF EARTH'S MAGNETIC FIELD

The following products all result from chemical weathering EXCEPT A. feldspar. B. silica in solution. C. iron oxides. D. clay minerals.

FELDSPAR

Continental crust has an overall composition corresponding closely to that of A. ultramafic. B. felsic to intermediate. C. mafic. D. peridotite.

FELSIC TO INTERMEDIATE

A trellis drainage pattern forms on A. horizontal lava flows. B. folded and tilted sedimentary rock layers of varying resistance. C. a dome. D. horizontal sedimentary rocks.

FOLDED AND TILTED SEDIMENTARY ROCK LAYERS OF VARYING RESISTANCE

Of the following materials, which one would make the longest lasting tombstone? A. limestone B. granite C. shale D. sandstone cemented with calcium carbonate.

GRANITE

Which materials would make the best aquifer? A. clay and silt B. unfractured granite C. gravel and sand D. highly cemented sandstone

GRAVEL AND SAND

What force drives mass wasting? A. heat B. friction C. gravity D. convection

GRAVITY

Where do rivers obtain the power to erode and transport sediments? A. heat B. electricity C. gravity D. friction

GRAVITY

The crust is typically thickest beneath A. high mountain ranges and plateaus on the continents. B. ocean-spreading centers. C. continental interiors like the Great Plains in North America. D. passive margins of continents where topography is very flat.

HIGH MOUNTAIN RANGES AND PLATEAUS ON THE CONTINENTS

The potential for geothermal energy is highest in a region that has numerous A. surface lakes. B. hot springs. C. caves. D. sinkholes.

HOT SPRINGS

Which of the following climatic regions experiences the most rapid chemical weathering? A. hot, low precipitation B. hot, high precipitation C. extremely cold, low precipitation D. extremely cold, high precipitation

HOT, HIGH PRECIPITATION

At a shallow depth, a well will most likely encounter a good water supply in which of the following locations? A. in granite on a ridge top B. in sandstone on a ridge top C. in shale in a valley bottom D. in sandstone in a valley bottom

IN SANDSTONE IN A VALLEY BOTTOM

Acid rain _________ the potential for chemical weathering. A. neutralizes B. increases C. does not affect D. decreases

INCREASES

If the gradient (slope) of a stream is increased, what happens to the velocity of the water? A. increases B. decreases C. remains unaffected D. may increase or decrease

INCREASES

Georgia soil, along with that of other warm, humid regions, is deep red in color. This color is due to A. iron oxides. B. feldspar. C. quartz. D. clay minerals.

IRON OXIDES

Mineral grains in sediments become magnetized by the Earth's magnetic field when A. they are struck a sharp blow by a meteorite. B. iron-rich minerals align parallel to the Earth's magnetic field. C. the Earth's magnetic field reverses itself. D. electricity from lightning strikes passes through the lava beds.

IRON-RICH MINERALS ALIGN PARALLEL TO THE EARTH'S MAGNETIC FIELD

Of the following minerals, the one most rapidly altered by chemical weathering would be A. mica (sheet silicate), such as biotite. B. amphibole (double chain silicate), such as hornblende. C. pyroxene (single chain silicate), such as augite. D. isolated silica tetrahedra mineral, such as olivine.

ISOLATED SILICA TETRAHEDRA MINERAL, SUCH AS OLIVINE

Stream competence is measured by the A. largest particle size the stream can transport. B. amount of material in the dissolved load. C. maximum width of the channel along the floodplain. D. total amount of suspended and bed load.

LARGEST PARTICLE SIZE THE STREAM CAN TRANSPORT

Of the following rock types, which is the most susceptible to groundwater solution, therefore making it the formation most likely to have caves? A. granite B. limestone C. sandstone D. shale

LIMESTONE

Which layer of the Earth experiences the most rapid increase in temperature with increasing depth? A. lithosphere B. mantle C. asthenosphere D. liquid outer core

LITHOSPHERE

Which of the following constitutes the rigid, outer layer of Earth's tectonic plates? A. asthenosphere B. crust C. lithosphere D. mantle

LITHOSPHERE

On which boundary in the Earth's interior does the greatest change in composition occur? A. lithosphere-asthenosphere boundary B. crust-mantle boundary C. mantle-core boundary D. boundary between the outer and inner core

MANTLE-CORE BOUNDARY

The angle of repose is the A. angle at which rock material is most stable. B. angle at which lava flows solidify without spreading out. C. angle of a slope that will no longer support large boulders and rock pillars. D. maximum slope at which loose material lies without cascading down.

MAXIMUM SLOPE AT WHICH LOOSE MATERIAL LIES WITHOUT CASCADING DOWN

Rock material that tends to result in the most fertile soils is _________ weathered. A. not at all C. moderately B. very weakly D. intensely

MODERATELY

The oceans contain by far the most amount of water on Earth. What is the second largest reservoir for water on Earth? A. lakes B. rivers C. groundwater D. polar ice and glaciers

POLAR ICE CAPS

Which of the following minerals does NOT chemically weather into a clay mineral? A. muscovite B. pyroxene C. K-feldspar D. quartz

QUARTZ

Particles tend to settle out of the suspended load in which order? A. clay, sand, pebbles B. sand, pebbles, cobbles C. pebbles, sand, silt D. clay, pebbles, sand

PEBBLES, SAND, SILT

The ability of a solid, such as rock, to allow fluids to pass through it is A. discharge. B. permeability C. capillary fringe D. porosity.

PERMEABILITY

Your beautifully landscaped house, built on an idyllic Georgia hillside site of small, irregularly undulating knolls and depressions, with trees tilted at interesting angles, has developed a bad case of broken and shifting foundation. The probable cause for the foundation problem is A. melting permafrost. B. that the house is built on an active earthflow. C. mudflow from an active nearby volcano. D. root wedging from the trees.

THAT THE HOUSE IS BUILT ON AN ACTIVE

The likely composition of the upper mantle is A. felsic. B. ultramafic. C. mafic. D. carbon (diamonds).

ULTRAMAFIC

Stream erosion and deposition are primarily controlled by a river's A. width. B. depth. C. velocity. D. channel shape.

VELOCITY

What happens chemically to the quartz sand grains in a calcite-cemented sandstone that is undergoing moderate chemical weathering? A. They combine with water. B. They dissolve. C. They oxidize. D. Virtually nothing—they become grains of quartz sand.

VIRTUALLY NOTHING - THEY BECOME GRAINS OF QUARTZ SAND

As opposed to the lithosphere, the asthenosphere is a ________ layer. A. brittle B. molten C. weak D. rigid

WEAK

Limestone and other carbonate rocks weather relatively fast in a ______ climate due to ______. A. dry / oxidation B. wet / physical weathering reaction C. dry / hydrolysis D. wet / dissolution promoted by carbonic acid

WET/DISSOLUTION PROMOTED BY CARBONIC ACID