GlyFinalTerms1

_________ explores the many and varied interactions between humans and that geologic environment.

The eventual result wass an earth differentiated into several major compositional zones: the central _____; the surrounding _______; and a thin ______ at the surface.

The ________ is a means of discovering basic scientific principles.

One or more ________ are formulated to explain the observations or data.

A hypothesis that is repeatedly supported by new experiments advances in time to the status of a _____, a generally accepted explanation for a set of data or observations.

Even when the population growth rate is constant, the number of individuals added per unit of time increases over time called _________.

Another way to look at the rapidity of world population growth is to consider the expected ________, the length of time required for a population to double in size.

Some scholars believe that we are already on the verge of exceeding the earth's ________, its ability to sustain its population at a basic, healthy, moderately comfortable standard of living.

An ______ is the smallest particle into which an element can be divided while still retaining the chemical characteristics of that element.

The ________, at the center of the atom, contains one or more particles with a positive electrical charge (______) and usually some particles of similar mass that have no charge (_______).

Circling the nucleus are the negatively charged _________.

The sum of the number of protons and the number of neutrons in a nucleus is the atom's ________.

Atoms of a given element with different atomic mass numbers- in other words, atoms with the same number of protons but different number of neutrons- are distinct ________ of that element.

Most atoms, however, can gain or lose some electrons. When this happens, the atom has a positive or negative charge and is called an _______.

Positively and negatively charged ions are called, respectively, ______ and ______

Some idea of the probable chemical behavior of elements can be gained from a knowledge of the __________.

A ________ is a chemical combination of 2 or more chemical elements, bonded together in particular proportions, that has a distinct set of physical properties (often very different from those of any of the individual elements in it).

In __________, the bond is based on the electrical attraction between oppositely charged ions.

Bonds between atoms may also form if the atoms share electrons called ________.

A _________ is a naturally occurring, inorganic, solid element or compound with a definite chemical composition and a regualar internal crystal structure.

__________ materials are solids in which the atoms or ions are arranged in regular, repeating patterns.

Not only is the external form of crystals related to their internal structure; so is _______, a distinctive way some minerals break up when struck.

It comes as no surprise, therefore, that by far the largest compositional group of minerals is the _______ group, all of which are compounds containing silicon and oxygen, and most of which contain other elements as well.

_________ is the general term used to describe those silicates- usually dark- colored (black, brown or green)- that contain iron and/or magnesium, with or without additional elements.

The __________ all contain carbon and oxygen combined in the proportions of one atom of carbon to 3 atoms of oxygen (written CO3).

The _______ all contain sulfur and oxygen in the ration of 1:4 (SO4).

When sulfur is present without oxygen, the resultant minerals are called ________.

Minerals containing just one or more metals combined with oxygen, lacking the other elements necessary to classify them as silicates, sulfates, carbonates, and so forth, are the _________.

__________ are minerals that consist of a single chemical element, and the minerals' names are usually the same as the corresponding elements.

The essence of the concept of the ________, explored more fully at the end of this chapter, is that rocks, far from being the permanent objects we may imagine them to be, are continually being changed by geological processes.

________ is the name given to naturally occurring hot, molten rock material.

An _______ rock is a rock formed by the solidification and crystallization of a cooling magma.

Under these conditions, the crystals have ample time to form and to grow very large and the rock eventually formed has mineral grains large enough to be seen individually with the naked eye. Arock formed in this way is a ________ igneous rock.

A magma that flows out on the earth's surface while still wholly or partly molten is called _______.

Lave is a common product of volcanic eruptions, and the term _______ is given to an igneous rock formed at or close to the earth's surface.

In extreme cases, where cooling occurs very fast, even tiny crystals may not form before the magma solidifies, and its atoms are frozen in a disordered state. The resulting clear, noncrystalline solid is a natural ________, obsidian.

At the lower end of the spectrum of rock-formation temperatures are the ___________ rocks.

_________ are loose, unconsolidated accumulations of mineral or rock particles that have been transported by wind, water, or ice, or shifted under the influence of gravity, and redeposited.

The set of processes by which sediments are transformed into rock is collectively described as _________.

___________ are formed from the products of the mechanical breakup of other rocks.

__________ form not from mechanical breakup and transport of fragments, but from crystals formed by precipitation or growth from solution.

A sequence of sedimentary rocks may include layers of _________, carbon-rich remains of living organisms; coal is an important example, derived from the remains of land plants that flourished and died in swamps.

A __________ rock is on that has formed from another, preexisting rock that was subjected to heat and/or pressure.

When hot magma formed at depth rises to shallower levels in the crust, it heats the adjacent, cooler rocks, and they may be metamorphosed; this is __________.

Metamorphism can also result from the stresses and heating to which rocks are subject during mountain building or plate-tectonic movement. Such metamorphism on a large scale, not localized around a magma body, is ___________.

In a rock subjected to directed stress, minerals that form elongated or platy crystals may line up parallel to each other. The resultant texture is described as _________.

He proposed that all the continental landmasses had once formed a single supercontinent, Pangea, which had them split apart, the modern continents moving to their present positions via a process called __________.

__________ is the study of large scale movement and deformation of the earth's layers.

__________ relates such deformation to the existence and movement of rigid "plates"over a weaker, more plastic layer in the earth's upper mantle.

An object is under ________ when force is being applied to it.

The stress may be __________, tending to squeeze or compress the object, or it may be ________, tending to pull the object apart.

A ___________is one that tends to cause different parts of the object to move in different directions across a plane or to slide past one another, as when a deck of cards is spread out on a tabletop by a sideways sweep of the hand.

_________ deformation resulting from stress. It may be temporary or permanent, depending on the amount and type of stress and on the physical properties of the material.

If __________ occurs, the amount of deformation is porportional to the stress applied, and the material returns to its original size and shape when the stress is removed.

Once the _________ of a material is reached, the material may go through a phase of _________ with increased stress. During this stage, relatively small added stresses yield large corresponding strains, and the changes are permanent: the material does not return to its original shape after removal of stress.

If stress is increased sufficiently, most solids eventually break, or ________.

In _______ materials, rupture may occur before there is any plastic deformation.

Together they make up the outer solid layer of the earth called the _________.

The layer below the lithosphere is the _________.

Each magnetic mineral has a __________, the temperature below which it remains magnetic, but above which it loses its magnetic properties.

This is the basis for the study of __________, "fossil magnetism" in rocks.

Thus was born the concept of _________, the moving apart of lithospheric plates at the ocean ridges.

The resulting curve, showing the apparent movement of the magnetic pole relative to the continent as a function of time, is called the ________ for that continent.

At a _________, lithospheric plates move apart.

This type of plate boundary, where one plate is carried down below (subducted beneath) another, is called a _________.

At a _________, as the name indicates, plates are moving toward each other.

The offset is a special kind of fault, or break in the lithosphere, known as a ________.

Another way to monitor rates and directions of plate movement is by using mantle _______. These are isolated aeas of volcanic activity usually not associated with plate boundaries.

For many years, the most widely accepted explanation was that the plates were moved by large _________ slowly churning in the plastic asthenosphere.

They occur along _______, planar breaks in rock along which there is displacement of one side relative to the other.

When movement along faults occurs, gradually and relatively smoothly, it is called ______.

When the stress at last exceeds the rupture strength of the rock (or the friction along a preexisting fault), a sudden movement occurs to release the stress. This is an ________, or seismic slip.

With the sudden displacement and associated stress release, the rocks snap back elastically to their previous dimensions; this behavior is called _________.

The point on the earth's surface direct;y above the focus is called the ________.

A _________, them is one along which the displacement is parallel to the strike (horizontal).

A _________ is one in which the displacement is vertical, up or down in the direction of dip.

Convergent plate boundaries are often characterized by ________, which are just reverse faults with relatively shallowly dipping fault planes.

When an earthquake occurs, it releases the stored-up energy in ________ that travel away from the focus.

________( P waves and S waves) travel through the interior of the earth.

________ are compressional waves. As they travel through matter, the matter is alternately compressed and expanded.

________ are shear waves, involving a side-to-side motion of molecules. Shear-type waves can also be demonstrated with a Slinky by streatching the coil out along the ground as before, but this time twitching one end of the coil sideways (perpendicular to its length).

Seismic ________ are somewhat similar to surface waves on water. That is, they cause rocks and soil to be displaced in such a way that the ground surface ripples or undulates.

Both types of body waves cause ground motions that are detectable using a _________.

The amount of ground motion is related to the _________ of the earthquake.

An alternative way of describing the size of an earthquake is by the earthquake's __________.

For example, severe earthquakes are generally followed by many _________, earthquakes that are weaker than the principal tremor.

The problem is __________. When wet soil is shaken by an earthquake, the soil particles may be jarred apart, allowing water to seep in between them, greatly reducing the friction between soil particles that gives the soil strength, and causing the ground to become somewhat like quick sand.

Coastal areas, especially around the Pacific Ocean basin where so many large earthquakes occur may also be vulnerable to _________. These are seismic sea waves, sometimes improperly called "tidal waves," although they have nothing to do with tides.

Such quiescent, or dormant, sections of otherwise- active fault zones are called _________.

In its early stages, earthquakes prediction was based particularly on the study of earthquake ___________, things that happen or rock properties that change prior to an earthquake.

This accounts for the _______ (mafic volcanic rock) that forms new sea floor at spreading ridges.

At a continental rift zone, the asthenosphere-derived melt is also mafic, but the rising hot basaltic magma may warm the more granite continental crust enough to produce some silica-rich melt also- making ________, the volcanic equivalent of granite- or the basaltic magma may incorporate some crustal material to make _______, intermediate in composition between the mafic basalt and felsic rhyolite.

The outpouring of magma at spreading ridges is an example of ________, the eruption of magma out of a crack in the lithosphere, rather than from a single pipe or vent.

This low, shieldlike shape has led to the term _________ for such a structure.

The bits of violently erupted volcanic material are described collectively as _______.

The cinders may pile up into a very symmetric cone-shaped heap known as a ________.

Many volcanoes erupt somewhat different materials at different times. They may emit some pyroclastics, then some lava, then more pyroclastics, and so on. Volcanoes build up in this layer-cake fashion are called_________, or alternately, _________, because they are built up of layers of more than one kind of material.

When not erupting explosively, the slow-flowing rhyolitic and andesitic lavas tend to ooze out at the surface like thick toothpaste form a tube, piling up close to the volcanic vent, rather than spreading freely. The resulting structure is a compact and steep-sided _________.

Volcanic ash and water can combine to create a fast-moving volcanic mudflow called a ________.

Another special kind of pyroclastic outburst is a deadly, denser-than-air mixture of hot gases and fine ash that forms a hot ___________, quite different in character from a rain of ash and cinders.

In the case of a volcanic island, large quantities of seawater may seep down into the rock, come close to the hot magma below, turn to steam, and blow up the volcano like an overheated steam boiler. This is called a ___________ or explosion.

A volcano is generally considered _______ if it has erupted with recent history.

When the volcano has not erupted recently but is fresh-looking and not too eroded or worn down, it is regarded as _______: inactive for the present but with the potential to become active again.

Historically, a volcano that has no recent eruptive history and appears very much eroded has been considered ________, or very unlikely to erupt again.

The ____________ has been developed as a way to characterize the relative sizes of explosive eruptions.

A _______ is an enlarged volcanic crater, which may be formed either by an explosion enlarging an existing crater or by collapse of a volcano after a magma chamber within has emptied.

The _________ includes all the water at and near the surface of the earth.

All of the water in the hydrosphere is caught up in the __________.

A ________ is any body of flowing water confined within a channel, regardless of size, although people tend, informally, to use the term river for a relatively large stream.

The region from which a stream draws water is its _________, or watershed.

The size of a stream may be described by its _________, the volume of water flowing past a given (or, more precisely, through a given cross section) in a specified length of time.

The total quanity of material that a stream transports by all these methods is called, simply, its ________.

Stream ________ is a measure of the total load of material a stream can move.

The steepness of the stream channel is called its _________.

Near the mouth, the stream is approaching its _______, which is the lowest elevation to which the stream can erode downward.

The __________ of such a stream (a sketch of the stream's elevation from source to mouth) assumes a characteristic concave-upward shape.

The relationship between the velocity of water flow and the size of particles moved accounts for one characteristic of stream-deposited sediments: They are commonly _________ by size and density, with materials deposited at a given point tending to be similar in size or weight.

If the stream is still carrying a substantial load as it reaches its mouth, and it then flows into still waters, a large, fan-shaped pile of sediment, a ______, may be built up.

A similarly shaped feature, an __________, is formed when a tributary stream flows into a more slowly flowing, large stream, or a stream flows from mountains into a plain.

Bends, or _________, thus begin to form in the stream.

It is eroded on the outside and downstream side of the meander, the _________, where the water flows somewhat faster (and the channel, too, tends to be a little deeper there as a result); _________, consisting of sediment deposited on the insides of meanders, build out the banks in those parts of the channel.

If the sediment load is very large in relation to water volume, the ________ may develop a complex pattern of many channels that divide and rejoin, shifting across a broad expanse of sediment.

This is the stream's _________, the area into which the stream spills over during floods.

The cutoff meaners are called _______.

When rainfalls or snow melts, some of the water sinks into the ground (_________).

Below ground, _________ moves it through soil and rock.

In times of higher discharge, the stream may overflow its banks, or _________.

The elevation of the water surface at any point is termed the ________ of the stream.

The stream is said to _______ when the maximum stage is reached.

Floods that affect only small, localized areas (or streams draining small basins) are sometimes called _________.

Floods that affect large stream systems and large drainage basins are called _________.

Fluctuations in stream stage or discharge over time can be plotted on a ________. Hydrographs spanning long periods of time are very useful in constructing a picture of the "normal" behavior of a stream and of that stream's response to flood-causing events.

Long-term records make it possible to construct a curve showing discharge as a function of recurrence interval for a particular stream or section of one called __________.

A flood event can then be described by its __________: how frequently a flood of that severity occurs, on average, for that stream.

Ifopen land is available, flood hazards along a stream may be greatly reduced by the use of __________. These ponds are large basins that trap some of the surface runoff, keeping it from flowing immediately into the stream.

___________ is a general term for various modifications of the stream channel itself that are usually intended to increase the velocity of water flow, the volume of the channel, or both.

The problem that local modifications may increase flood hazards elsewhere is sometimes also a complication with the building of ________, raised banks along a stream channel.

The western margin of North America is an ________, one at which there is an active plate boundary, with various sections of it involved in subduction or transform faulting.

The eastern margin of North America is a _________, far removed from the active plate boundary at the Mid-Atlantic Ridge.

A ________ is a gently sloping surface washed over by the waves and covered by sediment.

The ________ is that portion regularly washed by the waves as tides rise and fall.

The most effective erosion of solid rock along the shore is through wave action- either the direct poinding by breakers or the grinding effect of sand, pebbles, and cobbles propelled by waves, which is called _______, or abraison

When waves approach a beach at an angle, as the water washes up onto and down off the beach, there is also net movement of water laterally along the shoreline, creating a _________.

The net result is __________, gradual sand movement down the beach in the same general direction as the motion of the longshore current.

This, coupled with strong onshore winds piling water against the land, can result in unusually high water levels during the storm, a storm _______.

A distinctive coastal feature that develops where the land is rising and/or the water level is falling is a set of __________.

A portion of the floodplain may be filled by encroaching seawater, and the fresh water backs up above the new, higher base level, forming a __________.

Jutting points of land, or headlands, are more actively under attack than recessed bays because wave energy is concentrated on these headlands by _________, deflection of the waves around irregularities in the coastline.

__________ are long, low, narrow islands paralleling a coastline somewhat offshore from it.

An _________ is a body of water along a coastline, open to the sea, in which the tide rises and falls and in which fresh and salt water meet and mix to create brackish water.

It tugs constantly downward on every mass of material everywhere on earth, causing a variety of phenomena collevtively called _________, or _________.

_________ is a general term for the results of rapid mass movements.

The downslope pull tending to cause mass movements, called the _________, is related to the mass of material and the slope angle.

Counteracting the shearing stress is friction, or, in a coherent solid, _________.

For dry, unconsolidated material, the ____________ is the maximum slope angle at which the material is stable.

True _________ are most common in northern polar latitudes.

The grinding and pulverizing action of massive glaciers can produce a ________ of clay-sized particles, less than .02 millimeter in diameter.

So-called _________ are somewhat similar in behavior to quick clays but may be formed from different materials.

When downslope movement is quite slow, even particle by particle, the motion is described as _______.

A _______ is a free-falling action in which the moving material is not always in contact with the ground below.

Falls are most often _______.

The coarse rubble that accumulates at the foot of a slope prone to rockfalls is _________.

In a ________, a fairly cohesive unit of rock or soil slips downward along a clearly defined surface or plane.

__________ can occur in rock or soil. A rotational movement of the soil mass typically accompanies the downslope movement. A scarp may be formed at the top of the slide.

In a ________, the material moved is not coherent but moves in a more chaotic, disorganized fashion, with mixing of particles within the flowing mass, as a fluid flows.

A flow involving a wide variety of materials- soil, rocks, trees, and so on- together in a single flow is a __________ , or __________, the latter term more often used for water- saturated debris.

A _________ is a mass of ice that moves over land under its own weight, through the action of gravity.

Glaciers are divided into 2 types on the basis of size and occurence. The most numerous today are the ________, also know as mountain or valley glaciers.

The larger and rarer ___________ are also know as ice caps or ice sheets.

At some point, the advancing edge of the glacier terminates, either because it flows out over water and breaks up, creating icebergs by a process known as _________, or, more commonly, because it has flowed to a place that is warm enough that ice loss by melting or evaporation is at least as rapid as the rate at which new ice flows in.

The set of processes by which ice is lost from a glacier is collectively called _________.

The _____________ is the line on the glacial surface where there is no net gain or loss of material.

On a very small scale, bits of rock that have become frozen into the ice at the base of a glacier act like sandpaper on solid rock below, making fine, parallel scratches, called _______, on the underlying surface.

Erosion by the scraping of ice or included sediment on the surface underneath is ________.

Some of the till may be transported and redeposited by the meltwater, whereupon the resultant sediment is called _________.

Till and outwas together are 2 varieties of glacial ________.

A landform made of till is called a _________.

Where winds blow consistently form certain directions, exposed boulders may be planed off in the direction(s) from which they have been abraded, becoming ________ ("wind-made" rocks).

_________ is the wholesale removal of loose sediment, usually fine-grained sediment, by the wind.

Where sediment is transported and deposited by wind, the principal depositional feature is a _______, a low mound or ridge, usually made of sand.

They pile up a bit at the peak, like windswept snow cornices on a mountain, then tumble down the steeper face, or _________, which tends to assume a slope at the angle of repose of sand (or whatever size of particle is involved)

A deposit of windblown silt is known as ________.

Mamy of the features of wind erosion and deposition are most readily observed in __________.

Under these conditions, much of the moisture originally in the sir mass is forced out as precipitation, and the air is much drier when it moves farther inland and down out of the mountains. In effect, the mountain cast a ________ on the land beyond.

The term ___________, however, is generally restricted to apply only to the relatively rapid development of deserts caused by the impact of human activities.

In turn, heat (infrared rays) radiating outward from earth's surface may or may not be trapped by certain atmospheric gases, a phenomenon known as the ____________.

The permanently frozen zone is __________.

The roles of temperature and salinity are refleted in the name __________ (remember, "halite" is sodium chloride, salt, the most abundant dissolved material in the oceans) given to the largest scale circulation of the oceans.

__________ is the proportion of void space in the material- holes or cracks, unfilled by solid material, within or between individual mineral grains- and is a measure of how much fluid the material can store.

__________ is a measure of how readily fluids pass through the material.

Immediately above the impermeable material is a volume of rock or soil that is water-saturated, in which water fills all the accessible pore space, the __________, or ___________.

___________ is the water in the saturated zone.

Above the saturated zone is rock or soil in which the pore spaces are filled partly with water, partly with air: the ___________, or ___________.

The water in unsaturated soil is _________, and is often an important factor in agricultural productivity.

The _________ is the top surface of the saturated zone, where the saturated zone is not confined by overlying impermeable rocks.

The processes of infiltration and migration or percolation by which ground water is replaced are collectively called _________.

Groundwater ________ occurs where ground water flows into stream, escapes at the surface in a spring, or otherwise exits the aquifer.

A rock that holds enough water and transmits it rapidly enough to be useful as a source of water is an _________.

An __________ is a rock that may store a considerable quanity of water, but in which water flow is slowed, or retarded; that is , its permeability is low, regardless of its porosity.

When the aquifer is directly overlain only by permeable rocks and soil, it is described as an ___________.

A __________ is bounded above and below by low-permeability rocks (aquitards).

If a well is drilled into a confined aquifer, the water can rise above its level in the aqufer because of the extra hydrostatic (fluid) pressure. This is called an _________.

In such a system, rather than describing the height of the water table, geologists refer to the height of the __________, which represents the height to which the water's pressure would raise the water if the water were unconfined.

How readily ground water can move through rocks and soil is governed by permeability, but where and how rapidly it actually does flow is also influenced by differences in _________( potential energy) from place to place.

The height of the water table (in an unconfined aquifer) or of the potentiometric surface (confined aquifer) reflects the hydraulic head at each point in the aquifer. All else being equal, the greater the difference in hydraulic head between 2 points, the faster ground water will flow betweem them. This is a key result of _________.

In an unconfined aquifer, the result is a circular lowering of the water table immediately around the well, which is called a _________.

A further problem arising from groundwater use in coastal regions, aside from the possibility of surface subsidence, is __________.

Dissolution of these rocks by subsurface water, and occasional collapse or subsidence of the ground surface into the resultant cavities, creates a distinctive terrain known as _________.

There may be no obvious evidence at the surface of what is taking place until the ground collapses abruptly into the void, producing a __________.

___________ simply contains substantial amounts of dissolved calcium and magnesium.

__________ is defined in different ways for different purposes. Engineering geologists define it very broadly to include all unconsolidated material overlying bedrock.

_________ also called physical weathering, is the physical breakup of rocks without changes in the rocks' composition.

___________ involves the breakdown of minerals by chemical reaction with water, with other chemicals disolved in water, or with gases in the air.

At the very top is the _______, consisting wholly of organic matter, whether living or decomposed- growing plants, decaying leaves, and so on.

Below that is the ________. It consists of the most intensicely weathered rock material, being the zone most exposed to surface processes, mixed with organic debris from above.

Unless the local water table is exceptionally high, precipitation infiltrates down through the A horizon and below. In so doing, the water may dissolve soluble minerals and carry them away with it. This process is known as _________, and it may be especially intense just below the A horizon, as acids produced by the decay of organic matter seep downward with percolating water.

The _____, below the A horizon, is therefore also known as the zone of leaching. Fine grained minerals, such as clays, may also be washed downward through this zone.

Many of the minerals leached or extracted from the E horizon accumulate in the layer below, the _________, also known as the ___________.

Below the B horizon is a zone consisting principally of very coarsely broken-up bedrock and little else. This is the __________, which does not resemble out usual idea of soil at all.

The ________ soils were seen as characteristic of more humid regions where the climate is wetter, there is naturally more extensive leaching of the soil, and what remains is enriched in the less-soluble oxides and hydroxides of aluminum and iron, with clays accumulated in the B horizon.

From this observation came the term _________ for the soil of a dry climate. The presence of calcium carbonate makes it more alkaline.

A ________ may be regarded as an extreme kind of pedalfer. They develop in tropical climates with high temperatures and heavy rainfall, so they are severely leached.

A given ore deposit may be described in terms of the enrichment or ______________ of a metal of interest.

___________ is the term given to unusually coarse-grained igneous intrusions.

An _________ is a rock in which a valuable or useful metal occurs at a concentration sufficiently high, relative to average rocks, to make it economically worth mining.

They are mined primarily from igneous rocks called _________, which occur as pipe-like intrusive bodies that must have originated in the mantle.

In time, the fluids cool and deposit their dissolved minerals, creating a ___________ (literally, "hot water") ore deposit.

Such ores have been deposited directly as chemical sedimentary rocks. Layered sedimentary iron ores, called ___________.

When a body of seawater trapped in a shallow sea dries up, it deposits these minerals in _______ deposits.

The currents of a coastal environment can also cause sediment sorting and selective concentration of minerals. Such deposits, mechanically concentrated by water, are called ___________.

__________ methods are becoming increasingly sophisticated and valuable in mineral exploration.

Perhaps the most widespread undersea mineral resource is __________.

Overlying vegetation, soil, and rock are stripped off, the coal or other material is removed, and the waste rock and soil are dumped back as a series of _________.

The fine waste materials, or ________, that are left over may end up heaped around the processing plant to weather and wash away, much like spoil banks.

The _______ are those energy sources that formed from the remains of once living organisms.

It is not a single chemical compound. __________, or ________ comprises a variety of liquid hydrocarbon compounds ( compounds made up of different proportions of the elements carbon and hydrogen).

There are also gaseous hydrocarbons (______), of which the compound methane is the most common.

Therefore, oil and natural fas are among the _________ energy sources.

Most coal deposits contain significant amounts of ___________.

Enormous quantities of natural gas might exist in such __________; recent estimates of the amount of potentially recoverable gas in this form range from 150 to 2000 trillion cubic feet.

The process requires _________ conditions,in which oxygen is absent or nearly so, since reaction with oxygen destroys the organic matter.

Further burial, with more heat, pressure, and time, gradually dehydrates the organic matter and transforms the spongy peat into soft brown coal (_______) and then to the harder coals (________ and _________)

The conversion processes are called _________ (when the product is gaseous) and _________ (when the product is liquid fuel).

_______ us very poorly named. The rock, while always sedimentary, need not be a shale, and the hydrocarbon in it is not oil! the potential fuel in oil shale is a sometimes-waazy solid called ________, which is formed from the remains of plants, algae, and bacteria.

________, also known as oil sands, are sedimentary rocks containing a very thick, semisolid, tarlike petroleum called ________.

_______ is the splitting apart of atomic nuclei into smaller ones, with the release of energy.

_______ is the combing of smaller nuclei into larger ones, also releasing energy.

Some of the newly release neutrons can induce fission in other nearby uranium-235 in breaking up, and so the process continues in a ___________.

A _________ can maximize the production of new fuel.

Resultant overheating of the core might lead to _________, in which the fuel and core materials would deteriorate into a molten mass that might or might not melt its way out of the containment building and thus release high levels of radiation into environment.

At some point, then, the plant must be ___________-taken out of operation, broken down, and the most radioactive parts delivered to radioactive-waste disposal sites.

Direct production of electricity using sunlight is accomplished through ________, also called simply "solar cell".

Heat from the cooling magma heats any ground water circulating nearby. This is the basis for extracting ___________ on a commercial scale.

The __________ is the rate of increase of temperature with increasing depth in the earth.

Where geothermal gradients are at least 40 degrees C/ kilometer, even in the absence of much subsurface water, the region can be regarded as a potential geothermal resource of the __________ type.