Final Geology Lecture

At the present, glaciers cover about ________ of the surface of the continents.

10%

The best estimate of when the Universe formed is ________.

13.8 Ga

Earth is approximately how old?

4.54 billion years

Which of the following is NOT true about minerals?

All minerals are compounds of more than one element.

Which of the following statements best describes the rock cycle?

Any rock can change into another rock based on the conditions to which the rock is subjected.

Which eon saw the first single-celled organism?

Archean

Why does Earth have a magnetic field?

Because early in Earth's history the outer core behaved like a moving wire coil in an external magnetic field and produced Earth's magnetic field.

Why do earthquakes occur only above the brittle-ductile transition depth?

Below the transition, the rocks are too hot.

Which of the following statements about Earth's core is FALSE?

By volume, it is the largest compositional layer of Earth.

Which of the following images shows the formation of the Moon?

C

________ is a region that is plagued by mass wasting events.

California

The ________ occurred due to the creation of many new ecological niches that formed as a result of the breakup of Rodinia.

Cambrian explosion

Why is chemical weathering relatively rare in deserts?

Chemical weathering most often involves reaction with water, which is rare in deserts.

Why do deserts form in polar regions?

Cold air does not hold much moisture.

________ glaciers during the Pleistocene Ice Age stretched all the way to Illinois, Kansas, and Nebraska.

Continental

________ is the study of the history and structure of the Universe.

Cosmology

________ occurs when rocks bend, break, or flow during mountain building.

Deformation

Using the Mohs hardness scale below, which of the following statements is FALSE?

Diamonds are twice as hard as apatite.

________ metamorphism affects the greatest volumes of rock and produces the greatest variety in metamorphic rock types.

Dynamothermal

In the heliocentric model, ________.

Earth orbits around the Sun

________ melting occurs at subduction zones because the down-going plate ________.

Flux; contains abundant water

________ provide evidence of past life, and thus help geologists understand how life, and the environments they lived in, changed throughout Earth's history.

Fossils

________ regions are heated by volcanic sources.

Geothermal

Today, continental glaciers are limited to Antarctica and ________.

Greenland

________ power uses flowing water to produce energy.

Hydroelectric

Which of the following is NOT required for a substance to be considered a mineral?

It must contain carbon.

During the formation of Pangea, Africa collided with North America and created the Appalachian Mountains. Which of the following mountain ranges is a modern analogue for the ancient Appalachian Mountains?

Italian Alps

Why do scientists believe there was once liquid water on Mars?

Landforms such as river channels and sandbars are seen on Mars.

Why does physical weathering speed up the processes of chemical weathering?

Physical weathering produces fresh surfaces for chemical weathering to attack.

How does water get from the atmosphere into the groundwater system?

Precipitation falls on the ground and infiltrates the ground surface to the groundwater system.

________ ages are used to set the beginning and end points of eras, epochs, and periods on the geologic time scale.

Radiometric

________ deserts form on the leeward (dry) side of mountain ranges.

Rain-shadow

________ can be recognized as a series of U-shaped hills that are lined up and represent the ________ of the glacier.

Recessional moraines; retreat

The absence of ________ can indicate the presence of magma in the crust.

S-waves

________ stress results in the smearing out of rock.

Shear

Why would landslides be LESS likely to occur in areas that receive only moderate amounts of rainfall?

Small amounts of rain increase cohesion.

________ energy is NOT as useful in the Pacific Northwest as it would be in Texas.

Solar

An important contribution made by Copernicus is his (correct) assertion that the ________.

Sun is the center of Earth's orbit

________ occurs when rocks are pulled apart.

Tension

________ provides the largest tide-generating force.

The Moon

Why do deserts form at high elevations?

The air is too thin to hold much heat.

You have a choice to drill your water well into a shallow, unconfined aquifer or a deeper artesian aquifer. Drilling deeper will cost more money; however, you chose to drill into the artesian aquifer. Why?

The artesian aquifer will flow on its own, without a pump.

As the velocity of flow decreases, which of the following is NOT true?

The competence increases.

Why can mountains on Earth NOT grow as high as those on Mars?

The geothermal gradient on Earth is too high.

Uniformitarianism is succinctly summarized by which phrase?

The present is the key to the past.

At a river delta, which of the following is FALSE?

The stream channel becomes very straight because of the large sediment load.

Why does an artesian well flow without pumping?

The water in a confined aquifer is pressurized.

Which of the following statements about the water table is FALSE?

The water table is also called the potentiometric surface.

Imagine you are drilling and find water; how would you be able to tell if you have found a perched aquifer?

The water table is too high.

The first mammals appeared during the ________ Period.

Triassic

________ is the process whereby rocks from depth are exposed at the surface during mountain building.

Uplift

The internal ordering of mineral crystals can be detected using ________.

X-ray diffraction

Two layers of rock contain trilobites that have the same body morphology; however, one rock layer is a shale and the other is an ironstone. Can these two layers be used for correlation?

Yes, if the trilobites are the same, then the layers were formed at the same time.

The Himalayan mountain range was formed at which tectonic setting?

a convergent plate boundary

Minerals are all naturally occurring solid substances with a definable chemical composition. They must also possess ________.

a fixed crystalline structure (spatial arrangement of atoms and ions)

Cleavage in minerals refers to ________.

a tendency to break along planes of weakness

Deserts represent ________ of Earth's surface.

about 25%

Currently, almost all the glaciers on Earth are in a state of retreat, which means that the rate of ________ is less than the rate of ________.

accumulation; ablation

Which of the following factors decreases the risk of mass movement?

adding vegetation to the side of a hill

The principal concern with storing nuclear waste is ________.

allowing sufficient time for short-lived radioactive atoms to decay

In order for a well to function properly it must be drilled below the water table and into a(n) ________.

aquifer

A relatively impermeable layer of rock or sediment is termed a(n) ________ in hydrogeologic contexts.

aquitard

A well that flows without pumping is called a(n) ________ well.

artesian

Volcanic eruptions release ________, which can block some sunlight from reaching Earth.

ash

The lithosphere lies directly above the ________.

asthenosphere

Ultimately, the base level of a stream valley can be no lower than the ________.

average elevation of the sea

The Great Oxygenation Event occurred ~2.5 Ga and forced large amounts of ________ to precipitate out of the ocean.

banded iron formation

Beneath a blanket of sediments, oceanic crust is primarily composed of ________.

basalt

Why is the rock cycle important?

because it explains how rocks are constantly changing from one type to another

Why do geologists classify rocks?

because rocks are the key to determining the Earth's history

Geologists call individual layers of sedimentary rocks ________, whereas several of them together are called ________.

beds; strata

With regard to minerals, hardness refers to the ability to resist ________.

being scratched

The classification of coal is based on the concentration of carbon in the rock. Which of the following chain of processes causes the concentration of carbon to increase?

burial à chemical reactions à release of gases à concentration of carbon

The mineral calcite is in the ________ mineral class.

carbonate

Broadly, metamorphism involves ________.

changes in mineralogy and texture in response to heat and stress

Imagine you are holding a rock composed of small sand grains cemented together. What subclassification of sedimentary rock is this?

clastic

Mesas, buttes, and chimneys are all the result of ________.

cliff retreat

Which of the following lists contains only fossil fuels?

coal, oil, natural gas

Thermohaline circulation carries ________ water from the poles to the equator, where the water becomes ________.

cold; warm

Trace amounts of impurity in a mineral can commonly produce significant differences in ________ among individual crystals of this mineral.

color

Fewer than 50 minerals on Earth are ________.

commonly found in rocks

The distinction between the crust and the mantle is primarily on the basis of a difference in ________.

composition

Mountain ranges formed along subduction zones are formed, in part, by ________ in the crust.

compression

Folds are most often associated with ________ stress.

compressional

Imagine you have just bought some property and notice that the trees on the slope have curved trunks. What would be the most effective method to prevent additional movement of the hillside?

construct a retaining wall

Volcanic arcs form along ________ boundaries.

convergent

The lithosphere is composed of the ________.

crust and the uppermost part of the mantle

The density of seawater increases with ________ temperature and ________ salinity.

decreasing; increasing

Where would you expect to find metamorphic rocks forming?

deep inside a mountain range

In uniform sediments with a relatively constant and gentle slope at the surface, a ________ drainage network is expected.

dendritic

The blocks of rock used in construction are termed ________.

dimension stone

The Earth's magnetic field is a ________.

dipole, such as that produced by a bar magnet

A flowing artesian well is one that ________.

discharges groundwater at the ground surface without pumping

Which of these is NOT one of the components of deformation?

dissolution

Natural glass is NOT considered a mineral because it ________.

does not have a fixed crystalline structure

Tectonic foliation occurs under which of the following conditions?

ductile, shear stress

At transform plate boundaries, ________.

earthquakes are common but volcanoes are absent

At which geologic setting are you most likely to find anthracite coal forming?

edges of mountain ranges

Fission occurs when nuclear bonds of atoms are broken, releasing massive amounts of ________.

energy

Summed over the entire surface of Earth, the rate of spreading at divergent boundaries is ________ lithospheric consumption at subduction zones.

equal to

Unconformities represent ________ in the rock record.

erosion or nondeposition

Cells that have a nucleus are called ________ life.

eukaryotic

Which progression best describes how water goes from the ocean to a river?

evaporation ® precipitation ® runoff

Viscosity controls how ________.

fast a fluid flows

Earthquakes often occur along ________.

fault zones

Which of the following landforms would be the result of subsidence?

fore-arc basin

Most energy for human consumption in the industrial world comes from ________.

fossil fuels

In which type of silicate are the greatest proportion of oxygen atoms shared by pairs of adjacent tetrahedra?

framework silicates

The Sun was created at the center of the accretionary disk when the temperature became high enough for ________ to occur.

fusion

A periodic explosive eruption of steam and water from within the ground up through the surface is termed a(n) ________.

geyser

The slope of a stream surface measured between two points along its course is the ________.

gradient

Currents and wind are created by the interaction of ________ and ________ energy.

gravitational; external

As a rule, groundwater always flows from areas of ________.

greater hydraulic head to those of lesser hydraulic head

As compared to ultramafic rocks, mafic rocks have a ________.

greater proportion of silica

The water table surface mimics the topography in an area because ________.

groundwater flow rates are so low

A(n) ________ spring is an area where hot water naturally seeps from the ground.

hot

The Hawaiian island chain is an example of a(n) ________.

hotspot island chain

Which of the following is a mineral?

ice, which is water in the solid state

If an igneous rock is heated and melted it will form a(n) ________ rock.

igneous

Where is the best place to be in an earthquake?

in an empty field

Lithification occurs ________.

in the shallow subsurface

Which layer of Earth has the highest density?

inner core

Chemical weathering involves the breakdown of material due to ________.

interaction with water or air

In the whole Earth, the four most common elements (by mass) are oxygen, silicon, magnesium, and ________.

iron

At a subduction zone, the down-going (subducting) plate ________.

is always composed of oceanic lithosphere

Regional metamorphism ________.

is another name for dynamothermal metamorphism

The stream gradient of most rivers ________.

is greater near the source than near the mouth

The balance between the weight of a mountain range and the buoyancy provided by the underlying mantle is termed ________ equilibrium.

isostatic

The discharge of a river will increase if ________.

it rains in the drainage basin area

Diamonds are usually found in ________.

kimberlite

Physical weathering is more prevalent in the desert due to the ________.

lack of water for chemical reactions

Ore minerals, such as galena, tend to be different from typical minerals (such as quartz) in that they have a ________.

large specific gravity

In Wegener's evidence for continental drift, continents were proposed to fit together, such as the east coast of South America with the ________.

lower west coast of Africa

Hot, liquid rock beneath Earth's surface is termed ________.

magma

The difference between magma and lava is that ________.

magma is found beneath the surface, whereas lava is found at the surface

The correlation of data from geologic ________ and ________ helped geologists unravel the entire history of Earth.

maps; cross-sections

The elevation of the water table ________.

may rise during rainy periods and sink during droughts

The heavy bombardment was a time in which Earth was struck by many ________, which added ________ and kept the surface from cooling.

meteorites; heat

Nonfoliated metamorphic rocks are classified based on their ________.

mineral composition

Foliation is the alignment of ________ in a metamorphic rock.

minerals

During the Hadean Eon Earth's surface was ________.

molten

Igneous rocks form from ________.

molten rock cooling and forming crystals

What must happen in order to transform a metamorphic rock into a sedimentary rock?

mountain building

Cirques and horns are features associated with ________.

mountain glaciation

If an area experiences uplift it will form a ________; if it experiences subsidence it will form a ________.

mountain; depression

The ________ class of minerals are very good conductors due to the ability of the electrons in the atoms to move around.

native metals

A resource is considered renewable if ________.

nature can replace it within a short time span relative to human life

Presently, Earth's atmosphere is dominated by which two gases?

nitrogen and oxygen

Thermal (contact) metamorphism produces ________.

nonfoliated rocks only

Within the world's sedimentary rocks, fossils ________.

occur in an ordered sequence

Which of the following minerals is a silicate?

olivine

Within a meander, where is sediment most likely to be deposited?

on the inner banks of the meander

An episode of mountain building is termed a(n) ________.

orogeny

Earth's magnetic field is produced in the ________.

outer core

Which layer of Earth does NOT contain silicates?

outer core

A meander that is cut off to become completely isolated from the main channel but which retains water is a(n) ________.

oxbow lake

The ________ class of minerals includes a substance commonly known as rust.

oxides

The silica tetrahedron that forms the backbone of all the silicate minerals is composed of silicon and what other element?

oxygen

If a geologist finds thick accumulations of fossiliferous limestone, in what type of basin might they have been formed?

passive-margin

In general, the mantle is made of the rock ________ and has a(n) ________ composition.

peridotite; ultramafic

Material through which water readily flows is termed ________.

permeable

Which of the following is NOT a mineral?

petroleum

The process of differentiation results in all of the following EXCEPT ________.

planets forming atmospheres

The theory of ________ states that the lithosphere is broken into a series of plates that move relative to each other.

plate tectonics

When two different minerals have the same chemical formula but different crystal structures, they are said to be ________.

polymorphs

When a solution becomes oversaturated, new solid particles are said to ________.

precipitate from the solution

The extremely high ________ within Earth keeps the rocks solid.

pressure

Ash, cinders, and blocks are all types of ________.

pyroclastic debris

Which common rock-forming mineral shows up in all three major rock types (igneous, sedimentary, and metamorphic)?

quartz

Two common metamorphic rocks that typically lack foliation are ________ and ________.

quartzite; marble

The current estimate for the age of Earth of 4.57 Ga comes from ________.

radiometric age dating of meteorites

The ________ of a fault gives the average time between events.

recurrence interval

Some landslides include a mixture of loose sediment and debris called ________.

regolith

A birthdate is an example of a(n) ________ age.

relative

The difference in elevation in an area is called ________.

relief

The mid-ocean ridges are elevated above the surrounding seafloor because ________.

ridge rocks are hot and therefore have relatively low density

Terrestrial planets are mainly composed of ________ while Jovian planets are made dominantly of ________.

rock and metals; volatiles

Rocks are often recycled in a series of processes known collectively as the ________.

rock cycle

Erosional processes work to remove material from mountains; thus, overtime the topography will become less ________.

rugged

Evidence of ________ preserved in the rock record are the existence of multiple shallow inland seas.

sea-level rise and fall

The framework silicates are the most complicated because they ________.

share all four oxygen

Regions where Precambrian metamorphic rocks are exposed at the surface are termed ________.

shields

A body of rock affected by compressive stress will likely undergo ________.

shortening

The mantle is composed almost entirely of the mineral class ________.

silicates

The most common minerals within Earth are ________.

silicates

The core consists of two layers: the ________ inner core and ________ outer core.

solid; liquid

Seismic waves ________ when they move from the crust into the mantle.

speed up

Any place where groundwater naturally flows out of Earth's surface is termed a(n) ________.

spring

The recurrence of earthquakes along a single fault is referred to as ________.

stick-slip behavior

The term for a change in shape induced by stress is ________.

strain

A ________ consists of a sequence of similar rocks that can be found across a region.

stratigraphic formation

The color of a mineral in powdered form is termed ________.

streak

Seismic retrofitting is the process of ________.

strengthening existing buildings and structures

Force-per-unit area is termed ________.

stress

In an undisturbed sequence of sedimentary rocks, younger layers overlie older layers, according to the principle of ________.

superposition

Our Sun belongs to a galaxy known as ________.

the Milky Way

Hot groundwater is mineralized because ________.

the hot water dissolves minerals

Which of the following best describes the hydrologic cycle?

the movement of Earth's water through a series of reservoirs

Which is the larger of the two tidal bulges?

the one closest to the Moon

Geological evidence suggests that many millions of years ago, the Amazon basin drained toward the west rather than the east. What caused this drainage reversal?

the rise of the Andes Mountains

The Coriolis effect causes the apparent deflection of currents due to ________.

the rotation of Earth

The hydraulic gradient in Darcy's law is essentially the same as which of the following?

the slope of a line

How is the half-life of a radioactive parent isotope defined?

the time it takes for half of the parent isotope to decay to daughter isotope

What is the rock cycle?

the transformation of one rock type to another

Imagine you are digging a hole when the hole suddenly starts to fill with water. What have you found?

the water table

Which of the following is a type of physical weathering?

thermal expansion

At a minimum, how many seismic stations are necessary to locate the epicenter of an earthquake?

three

Sediments deposited directly by glaciers as they melt are termed ________.

till

Grains become rounded primarily during ________.

transportation

Landslides are more likely to occur in ________ regions.

tropical

Permeable rock or sediment between the water table and the land surface represents a(n) ________.

unsaturated zone

What process created the terrace that forms the cliff in the picture below?

uplift

Which type of situation would be more likely to produce folds?

warm, ductile crust under compression

The majority of erosion in the desert is due to ________.

water

Which of the following is NOT an example of a landform?

water

Gases that are abundantly emitted by volcanoes include ________.

water vapor, carbon dioxide, and sulfur dioxide

Which of the following does NOT affect the severity of damage from an earthquake?

weather

Geologists classify metamorphic rocks according to ________.

whether they are foliated