GEO 103 Final Exam

Cave formations lock paleoenvironmental information in their crystalline structures. What is an example of materials used to understand past environments in the vicinity of a modern cave?

-Samples of clays and muds from the floors of cave chambers -Small cores taken from calcium carbonate stalactites ****Carlsbad Caverns National Park****

U-235, the isotope of uranium

-commonly utilized in nuclear power plants -rare even in uranium oxide deposits - must be enriched before use as fuel

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

10%

The current interglacial interval began a little more than ... years ago.

10,000

continental crust is typically 35 km thick, but may be up to ... think under mountain ranges?

200 km

Approximately what percentage of Earth's surface is covered with water?

70%

The oil window (temperature range wherein organic matter is converted to petroleum without destroying it) lies between ...

90°C and 160°C

How does the rate at which a body of rock is deformed affect its behavior?

A rock deformed is likely to exhibit brittle behavior.

Example of a positive feedback mechanism

A runaway greenhouse effect

At depths of greater than 60 m, ice moves by plastic deformation. What causes this transition from brittle to ductile behavior?

An increase in temperature causes the glacier to melt and slide.

firn

An intermediate product in the transformation of snow to glacial ice

spring

Any place where groundwater naturally flows out of the surface of Earth

Why do earthquakes occur only above the brittle/plastic transition depth?

Below the transition, the rocks are too hot.

How are carbon dioxide (CO2) levels in the atmosphere affected by tectonic uplift of rocks and their resultant chemical weathering?

CO2 is removed from the atmosphere.

during what period were Most of the world's coal was deposited in coal swamps ?

Carboniferous

Before the discovery of coal, humans did NOT produce or consume energy.

False

Organic matter builds up evenly over the entire surface of the ocean floor.

False

Which is NOT one of the five fundamental sources of energy?

Fossil Fuels

what are examples of alternative hydrocarbon sources?

Gas hydrate, Tar sands, Oil shale

Mid-ocean ridges (MORs), which are the sites of new oceanic crust formation, are linear mountain chains that run along divergent plate boundaries. Why does an MOR sit up higher than the surrounding oceanic crust?

Hot materials are less dense and expand, thus the new crust will sit higher than the surrounding crust.

when is a resource considered renewable?

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

fuel

Matter that stores energy in a usable and transportable form

The effect of periodic changes in Earth's orbital eccentricity and magnitude and direction (precession) of Earth's axial tilt on the advance and retreat of ice sheets was first proposed by who?

Milankovitch

five fundamental sources of energy

Nuclear fusion in the Sun (solar energy) Gravity generated by the Earth & Moon. Nuclear fission reactions. Energy in the interior of the Earth. Energy stored in chemical bonds.

Why do ocean water and sea ice have very different effects on air temperatures?

Ocean water absorbs solar energy much more effectively than sea ice.

Which statement best summarizes the development of the geologic time scale?

Relative ages for sedimentary strata were known well before accurate numerical dates for these rocks could be provided.

What do you take to be the main threats to Everglades National Park today?

Sea level rise Urbanization Storm-related damages Air pollution

Which of these statements about the U.S. supply of strategically important metals is true?

The United States imports 100% of many strategic minerals.

the fold hinge

The central portion of high curvature on a fold

Uniformitarianism is succinctly summarized by which phrase?

The present is the key to the past.

what are meandering streams's channel?

a channel that is highly sinuous (curvy)

Which of these features help a geologist recognize a fault?

a shattered rock consisting of visible angular fragments, different rock units juxtaposed against each other, a small step on the landscape

malleability

ability of a metal to be bent, molded, and stretched

A glacier will always advance from its source area if the rate of accumulation is greater than the rate of what?

ablation

the metal ores found in veins within plutons typically occur....

alongside abundant quartz

The principal of superposition

an undisturbed sequence of sedimentary rocks, younger layers overlie older layers

Magma has intruded into some limestone, and a marble rind formed surrounding the granite pluton. The marble rind must be younger than the limestone according to the principle of ....

baked contacts

Glacial ice exhibits ... behavior near the top but ... behavior beneath a depth of 60 m.

brittle; plastic

which of the following is an alloy?

bronze

how are Maar volcanoes are created?

by steam and gas explosions when hot magma interacts with downward flowing water.

An important long-term factor determining whether glacial ice will form on the continents has likely been the proportion of which gas in the atmosphere?

carbon dioxide

Which gas is most abundantly produced from the burning of coal?

carbon dioxide

During the last ice age, a ... glacier covered much of the northern United States.

continental

what were the first ores that were widely smelted by humans to produce metal?

copper

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

decreasing; increasing

in uniform sediments with a relatively consistant and gentle slope at the surface, a ..... drainage network is expected

dendritic

Compared with the continental crust, the oceanic crust is ....

denser

normal, reverse, and thrust are examples of what kind of fault?

dip- slip

The principal of original horizontality

direct result of gravity

on a geologic map, if the contacts between sedimentary rock units form a bullseye pattern of concentric circles, with the oldest unit in the center, what is the underlying structure?

dome

isostasy

equilibrium between parts of the earth's crust, behaving as consisted of blocks floating on the underlying mantle -rising if material (such as an ice cap) is removed -sinking if material is deposited.

What is the distinction between joints and faults?

faults are fractures along which displacement has occurred; displacement does not occur along joints

Which fossil fuel, oil or natural gas, is found at greater depths within Earth, and why?

gas, because it is more stable at high temperatures

A geologist's compass vs. the common orienteering compass

geologist's compass have an inclinometer, measuring dip and plunge angles

what is the slope of a stream surface measured between two points along its course?

gradient

ephemeral streams

have flowing water either episodically or during only a portion of the year

what does Permeability measure?

how well the pores within rock are connected

mineral-rich veins with plutons, deposited by hot groundwater into fractures with the rock, characterize what?

hydrothermal deposits

Commercial ore deposits are most likely to be found associated with what types of rock?

igneous rocks

Over last 20 years, the amount of Arctic Ocean's ice has been decreasing each summer, exposing more of the Arctic Ocean to the atmosphere each summer. Would this cause the total absorption of heat in the Arctic to increase or decrease?

increase

the discharge of a river traveling through a temperature region will typically ..... downstream; the discharge of a river traveling through a .....

increase ; decrease

what are the most important ores of iron?

iron oxides

In a humid climate, the topography of the water table ....

is a subdued (less steeply sloping) mimic of surface topography

Natural gas production vs. oil

is produced at higher temperatures than oil

MVT (Mississippi Valley-type) deposits are secondary enrichments primary of ...... and .....

lead ; zinc

Hydrocarbons consisting of short carbon chains are ....

more volatile than hydrocarbons with longer chains

what properly illustrates the principal of isostasy?

mountains stand high because they are gravitationally balanced by their deep crustal roots

A mineral that consists of only metal atoms is known as a(n)

native metal

what are the high electrical conductivity associated with metallic bonds found in?

native metal and purer metals artificially derived from ores

At the equatorial ocean basins, the sea surface temperatures may reach 25°C or greater. What is the range of temperatures for the seafloor, approximately 4−5 km below?

near freezing (1°C−2°C)

slag

nonmetals extracted from metals during smelting

Within the world's sedimentary rocks, fossils ....

occur in an ordered sequence

If all Earth history were compressed into a single year, Homo Sapiens would first appear when?

on December 31, at 11:59pm (just before the ball drops on New Year's Eve)

what do majority of the hydrocarbons within oil and natural gas that derive from the breakdown of organic matter, from from ?

once-living plankton

Milankovitch cycles describe variation in Earth's ....

orbit and tilt

An episode of mountain building

orogeny

The stereotypical gold rush prospector panning for gold in a streambed is an example of exploiting ... deposits.

placer

slickenside

polished surface produced by the scraping of rock along a fault

groundwater mining

pumping out water faster than it can be replenished by recharge

Numerical ages for boundaries between time units on the geologic time scale primarily resulted from the study of ..., in conjunction with relative age data.

radiometric dating of igneous rocks

in a region with prominent orthogonal sets of joints, what drainage network is expected?

rectangular

cratons

regions of continents that have not been subject to orogeny during the past one billion years

Which of these features would NOT help a geologist recognize a fault?

regularly spaced quartz veins

how were nearly all the present mountain ranges formed?

repeated cycles of collision and rifting

the base level of a stream valley can be no lower than what?

sea level

What will a body of rock affected by compressive stress likely undergo?

shortening

how do sulfide materials typically respond in magma chambers?

sink to the bottom

Glaciers form as fresh ... falls to the ground and accumulates. The accumulation adds pressure, which compresses the ... until they form a packed granular material called .... Some material melts and then ... in the pore spaces to create a solid mass of ice.

snow; snowflakes; firn; refreezes

Which list correctly orders the three types of subsurface water from shallowest to deepest?

soil moisture, vadose zone water, groundwater

The term for a change in shape induced by stress

strain

in what kind of terrain would you expect to find a placer-type deposit?

stream bed

What will a body of rock affected by tensile stress likely undergo?

stretching

right- lateral and left- lateral are examples of what kind of fault?

strike slip

The presence of gold in western South America can be attributed to processes associated with ....

subduction

which types of ores are commonly concentrated in magmatic deposits?

sulfides

Precisely speaking, a measured radiometric age for a mineral crystal within an igneous rock, denotes the amount of time that has passed since what....?

temperature of the crystal became equal to the closure temperature for the mineral

The high electrical conductivity associated with metallic bonds results from what?

the ability of outer electrons to move freely from atom to atom

isostatic equilibrium

the balance between the weight of a mountain range and the buoyancy provided by the underlying mantle

If an igneous dike cuts across a sequence of sedimentary beds ....

the beds must be older

thermohaline circulation

the planet-wide circulation of water in Earth's oceans, which relies on contrasting temperature and salinity

trunk

the primary stream fed by tributaries within a dendritic drainage network

as the velocity flow decreases...

the saltation of the bed load may cease the flow tends to become more laminar suspended sediment starts to be deposited

Albedo

the tendency of a surface to reflect solar energy instead of absorb it.

half-life of a radioactive parent isotope description

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

If the relative ages of two formations are known, what else about them can be inferred?

their relative position in a sequence of rock layers

in a region characterized by parallel series of ridges and valleys, what drainage network is expected?

trellis

currently, igneous and metamorphic rocks are the only sources of commercially available minerals.

true

Increasing ratios of oxygen-18 to oxygen-16 in glacial ice indicate ....

warming temperatures

Which of the following is a renewable resource?

wind

primarily, why DONT Nuclear chain reactions within power plants produce bomb-like explosions ?

within nuclear fuel rods, the density of uranium is insufficient to become explosive