Geology

Flood basalt

describes the fluid, water-like, basaltic lava flows that cover an extensive region in the northwestern United States known as the Columbia Plateau. When silica-rich magma is extruded, pyroclastic flows consisting largely of ash and pumice fragments usu¬ally result.

A system

A group of interacting parts that form a complex whole

divergent plate boundaries

Ac¬tive areas of volcanism are found, along oceanic ridges where seafloor spreading is occurring

Detrital

All ___ rocks have a clastic texture, which consists of discrete fragments and particles that are cemented and compacted together. The main criterion for subdividing the ___ rocks is particle size. Common ____ rocks include conglomerate, sandstone, and shale. The primary basis for distinguishing among different rocks in the chemical group is their mineral composition

Fissures

Although volcanic eruptions from a central vent are the most familiar, by far the largest amounts of vol¬canic material are extruded from cracks in the crust called

Crystallization

As magma cools, the ions that compose it arrange them¬selves into orderly patterns during a process called

compounds

Atoms combine with each other to form more complex sub¬stances called..?

partial melting

Because melting is generally not complete, a process called ____ produces a melt made of the lowest-melting-temperature minerals, which are higher in silica than the original rock. Thus, magmas generated by partial melting are nearer to the felsic (granitic) end of the compositional spectrum than are the rocks from which they formed.

slate, phyllite, schists, and gneiss

Common foliated metamorphic rocks include

Nebular hypothesis

Describes the formation of the solar system. The planets and Sun began forming about 5 billion years ago from a large cloud of dust and gases. As the cloud contracted, it began to rotate and assume a disk shape. Ma¬terial that was gravitationally pulled toward the center be¬came the protosun. Within the rotating disk, small centers, called protoplanets, swept up more and more of the cloud's debris. Because of the high temperatures near the Sun, the inner planets were unable to accumulate many of the ele¬ments that vaporize at low temperatures. Because of the very cold temperatures existing far from the Sun, the large outer planets consist of huge amounts of ices and lighter materials. These substances account for the comparatively large sizes and low densities of the outer planets

crystal setting

During the crystallization of magma, if the earlier-formed minerals are denser than the liquid portion, they will settle to the bottom of the magma chamber during a process called ?

nonmetallic resources

Earth materials that are not used as fuels or processed for the metals they contain are referred to as ___. Many are sediments or sedimentary rocks. The two broad groups of _____ are building materials and industrial minerals. Limestone, perhaps the most versa¬tile and widely used rock of all, is found in both groups.

Layers, called strata, or beds, are probably the single most characteristic feature of sedimentary rocks. Other features found in some sedimentary rocks, such as ripple marks, mud cracks, cross-bedding, graded bedding, and fossils, also give clues to past environments.

Features of sedimentary rocks

based on differences in chemical composition and on the basis of changes in physical properties

How are Earth's internal structures divided?

Texture and mineral composition

How are Igneous rocks classified?

Weathering may create ore deposits by concentrating minor amounts of metals into economically valuable deposits. Processes include removing nonvaluable components of the rock or, in contrast, removal and later concentration of the valuable components.

How can weathering create ore?

By applying such principles as the law of superposition and the principle of fossil succession.

How do scientists develop a geologic time scale?

Slow cooling results in the formation of rather large crystals. Conversely, when cooling occurs rapidly, the outcome is a solid mass consisting of tiny intergrown crys¬tals. When molten material is quenched instantly, a mass of unordered atoms, referred to as glass forms.

How does the rate of cooling affect size of crystals?

according to their shape and by their orientation with respect to the host rock, gen¬erally sedimentary rock/\.The two general shapes are tabular (sheetlike) and massive. Intrusive igneous bodies that cut across existing sedimentary beds are said to be discordant; those that form parallel to existing sedimentary beds are concordant

Intrusive igneous bodies are classified by?

(1) lava flows (pahoehoe flows, which resemble twisted braids; and aa flows, consisting of rough, jagged blocks; both form from basaltic lavas); (2) gases (primarily water vapor); and (3) pyroclastic material (pulverized rock and lava fragments blown from the volcano's vent, which include ash, pumice, lapilli, cinders, blocks, and bombs.) (3) Successive eruptions of lava from a central vent result in a mountainous accumulation of material known as a volcano.

Materials associated with a volcanic eruption

Geneiss

Metamorphic rocks with a band¬ed texture are called?

The mineral composition of an igneous rock is the conse¬quence of the chemical makeup of the parent magma and the environment of crystallization. Igneous rocks are di¬vided into broad compositional groups based on the per¬centage of dark and light colored minerals they contain. Granite and rhyolite are composed most¬ly of the light-colored silicate minerals. Mafic rocks (e.g., basalt and gabbro) are high in iron, magnesium, and calcium, low in silicon, and are dark gray to black in color.

Mineral composition of an igneous rock

reserves/deposits

Mineral resources are the endowment of useful minerals ul¬timately available commercially. Resources include already identified deposits from which minerals can be extracted profitably, called _____, as well as known ____ that are not yet economically or technologically recoverable. _____ inferred to exist, but not yet discovered, are also con¬sidered mineral resources. The term ore is used to denote those useful metallic minerals that can be mined for a prof¬it, as well as some nonmetallic minerals, such as fluorite and sulfur, that contain useful substances.

calderas

Most volcanoes are fed by conduits or pipes. As erosion pro¬gresses, the rock occupying the pipe is often more resistant and may remain standing above the surrounding terrain as a volcanic neck. The summits of some volcanoes have large, nearly circular depressions called ____ that result from collapse following an explosive eruption. ____ also form on shield volcanos by subterranean drainage from a central magma chamber, and the largest ___ form by the discharge of colossal volumes of silica-rich pumice along ring fractures

marble (parent rock: lime¬stone) and quartzite (most often formed from quartz sand¬stone).

Nonfoliated rocks include

oxygen, sili¬con, aluminum, iron, calcium, sodium, potassium, and magnesium

Of the nearly 4000 minerals, no more than a few dozen make up most of the rocks of Earth's crust and, as such, are clas¬sified as rock-forming minerals. 8 elements make up the bulk of these minerals and repre¬sent over 98 percent (by weight) of Earth's continental crust.What are the eight elements?

assimilation or magma mixing

Once a magma body forms, its composition can change through the incorporation of foreign material, a process termed?

magmatic differentiation

Owing to the fact that crystal settling removes the earlier-formed minerals; the remaining melt will form a rock with a chemical composition much differ¬ent from the parent magma. The process of developing more than one magma type from a common magma is called?

1) by inorganic processes, such as evaporation and chemical ac¬tivity; or (2) by organic processes of water-dwelling organ¬isms that produce sediments of biochemical origin. Limestone, the most abundant chemical sedimentary rock, consists of the mineral calcite (CaCO3) and forms either by inorganic means or as the result of biochemical processes. Inorganic limestones include travertine, which is commonly seen in caves, and oolitic limestone, consisting of small spherical grains of calcium carbonate. Other common chemical sed¬imentary rocks include dolostone (composed of the calcium-magnesium carbonate mineral dolomite), chert (made of microcrystalline quartz), evaporites (such as rock salt and rock gypsum.)

Precipitation of chemical sediments occurs in two ways:

crystal form, luster, color, streak, hardness, cleavage, fracture, and density or specific grav¬ity. In addition, a number of special physical and chemical properties (taste, smell, elasticity, malleability, feel, magnetism, double refraction, and chemical reaction to hydrochloric acid) are useful in identifying certain minerals. Each mineral has a unique set of properties that can be used for identification.

Properties of minerals

particle size, mineral makeup, and climatic factors, particularly temperature and moisture

Rates of weathering depends on?

Rcomposition and amount of exposed surface area.

Rocks weather at different rates depending on?

igneous processes.

Some of the most important accumulations of metals, such as gold, silver, lead, and copper, are produced by what? The best-known and most important ore deposits are generated from hydrothermal (hot-water) solutions. Hydrothermal deposits are thought to originate from hot, metal-rich fluids that are remnants of late-stage magmatic processes. These ion-rich solutions move along fractures or bedding planes, cool, and precipitate the metal produce vein deposits. In a disseminated deposit (e.g. the world's copper deposits), the ores from hydrothermal solutions are distributed as minute masses throughout the entire rock mass.

sills

Tabular, concordant bodies, form when magma is injected along the bedding surfaces of sedimentary rocks. In many respects, ___ closely resemble buried lava flows.

(1) contact or thermal metamorphism, (2) hydrothermal metamorphism and (3) burial and subduction zone metamorphism, and (4) regional metamorphism. Contact metamorphism occurs when rocks are in contact with an igneous body, resulting in the formation of zones of alteration around the magma.

The four geologic environments in which metamorphism commonly occurs are

mountain belts and the stable interior

The largest features of hte continents can be divided into two categories?

the chemical composition of the magma from which it crystallizes. As magma cools those minerals with higher melting points crystallize before minerals with lower melting points.

The mineral makeup of an igneous rock is ultimately de¬termined by?

carbonate minerals, calcite and dolomite. Two other nonsilicate minerals frequently found in sedimentary rocks are halite and gypsum.

The nonsilicate mineral groups contain several eco¬nomically important minerals. The more common nonsilicate rock-forming miner¬als include the...

Chemical

The primary basis for distinguishing among different rocks in the ____ group is their mineral composition. Some ____ rocks, such as those deposited when seawater evaporates, have a nonclastic texture in which the minerals form a pattern of interlocking crystals. However, in reality, many of the sedimentary rocks classified into the ___ group also contain at least small quantities of detrital sedi¬ment. Common ___ rocks include limestone, rock gyp¬sum, and coal (e.g., lignite and bituminous).

the magma's composition, its temperature, and the amount of dissolved gases it contains. As lava cools, it begins to congeal, and as viscosity increases, its mobili¬ty decreases. The viscosity of magma is directly related to its silica content. Rhyolitic (felsic) lava, with its high silica con¬tent (about 70 percent), is very viscous and forms short, thick flows. Basaltic (mafic) lava, with lower silica con¬tent (about 50 percent), is more fluid and may travel a long distance before congealing. Dissolved gases tend to increase the fluidity of magma and, as they expand, pro¬vide the force that propels molten rock from the vent of a volcano.

The primary factors that determine the nature of volcanic eruptions

(1) divergent boundaries, where plates move apart; (2) convergent bound-aries, where plates move together, causing one to go beneath another, or where plates collide, which occurs when the lead¬ing edges.<are made of continental crust; and (3) transform fault boundaries, where plates slide past one another.

Three distinct types of plate boundaries?

The solid Earth (or geosphere), the water portion of our planet (the hydrosphere), and Earth's gaseous envelope (the atmosphere). Also the biosphere (life)/

Three major parts of Earth's physical environment?

(1) as detrital material, which originates and is transported as solid particles from both mechanical and chemical weathering, which, when lithified, forms detrital sedimentary rocks; and (2) from soluble material produced largely by chemical weathering, which, when precipitated, forms chemical sedi¬mentary rocks. Coal is the primary example of a third group called organic sedimentary rocks which consist of organic carbon from remains of partially altered plant material.

Two basic principles of sedimentary rock

continents and ocean basins. The elevation differences between continents and ocean basins are primarily the result of differences in their respective densities and thicknesses.

Two different divisions of Earth's surface and a significant difference

Detrital and chemical

Two groups of Sedimentary rock

1) The Sun, which drives the external processes that occur in the atmosphere, hydrosphere, and at Earth's surface, and (2) Heat from Earth's interior that powers the internal process¬es that produce volcanoes, earthquakes, and mountains.

Two sources of energy that power the Earth system?

soil characteristics, climate, slope and plant cover.

Weathering creates particles capable of being eroded, transported and eventually deposited. Rates of erosion are influenced by?

Lithosphere, asthenosphere, mesophere, outer core, inner core.

What are the layers inside the Earth?

The mineral makeup of the parent rock determines, to a large extent, the degree to which each metamorphic agent will cause change. Heat is the most important agent be¬cause it provides the energy to drive chemical reactions that result in the recrystallization of minerals. Pressure, like temperature, also increases with depth. When sub¬jected to confining pressure, minerals may recrystallize into more compact forms. During mountain building, rocks are subjected to differential stress, which tends to shorten them in the direction pressure is applied and lengthen them in the direction perpendicular to that force. At depth, rocks are warm and ductile, which accounts for their ability to deform by flowing when subjected to dif¬ferential stresses. Chemically active fluids, most com¬monly water containing ions in solution, also enhance the metamorphic process by dissolving minerals and aiding the migration and precipitation of this material at other sites.

What causes metamorphic rocks?

when magma cools and solidifies. Extrusive, or volcanic, igneous rocks result when lava cools at the surface. Magma that solidifies at depth produces in-trusive, or plutonic, igneous rocks

When do igneous rocks form?

Mesosphere

Where rocks are very hot and capable of very gradual flow

Inner core

a dense sphere of solid iron and nickel at the center of Earth

outer core

a layer of molten iron and nickel that surrounds the inner core of Earth where Earth's magnetic field is generated

Schistosity

a type of foliation defined by the parallel alignment of medium- to coarse-grained platy minerals

Chemical weathering

alters the composition of rock. Water containing oxygen and (or) carbon dioxide is the most important agent.

Shield cones

are broad, slightly domed volcanoes built primarily of fluid, basaltic lava

Laccoliths

are similar to sills but form from less fluid mag¬mas that collect as lens-shaped masses that arch the over¬lying strata upward

Dikes

are tabular, discordant igneous bodies produced when magma is injected into fractures that cut across rock layers.

elements.An element is a large collection of electrically neutral atoms, all having the same atomic number.

building blocks of minerals?

sedimentary. Coal originates from large quantities of plant remains that accu¬mulate in an oxygen-deficient environment, such as a swamp. More than 70 percent of present-day coal usage is for the generation of electricity. Air pollution from the sulfur-oxide gases that form from burning most types of coal is a significant environmental problem.

coal, petroleum, and natural gas, the fossil fuels of our modern economy, are all associated with what type of rock?

foliation

develops as platy or elongated minerals are rotated into parallel alignment, recrystallize to form new grains that exhibit a preferred orientation, or are plas¬tically deformed into flattened grains that exhibit a pla¬nar alignment.

Closed system

energy moves freely in and out, but matter does not enter or leave the system.

physical geology

examines the materials composing Earth and the processes that operate beneath and upon its surface.

The size of the particles in a detrital rock indicates the energy of the medium that transported them. For example, gravels are moved by swift¬ly flowing rivers, whereas less energy is required to trans¬port sand. Common detrital sedimentary rocks include shale (silt- and clay-size particles), sandstone, and conglomerate (rounded gravel-size particles) or breccia (angular gravel-size particles).

how do you distinguish among various detrital sedimentary rocks?

intraplate volcanism

in the interiors of plates themselvesRising plumes of hot mantle rock are the source of most ___ volcanism

convergent plate boundaries

in the vicinity of ocean trenches where one plate is being subducted beneath another

Rock cleavage

is a type of foliation in which .rocks split cleanly into thin slabs along surfaces where 'platy minerals are aligned

Metamorphic

is the transformation of one rock type into another. ____ form from preexisting rocks (igneous, sedimentary, or other metamorphic rocks) that have been altered by the agents of ____, which include heat, pressure (stress), and chemically active fluids. Dur¬ing ____ the material essentially remains solid. The changes that occur in ____ rocks are textural as well as mineralogical.

Silicates. All silicate minerals have the negatively charged silicon-oxygen tetra¬hedron as their fundamental building block. Each silicate mineral has a structure and a chemical composition that indicates the con¬ditions under which it was formed.

most common mineral group.

Positive feedback mechanisms

natural systems that tend to enhance change

negative feedback mechanism

natural systems that tend to resist change and thus stabilize the system.

Mineral

naturally occurring inorganic solid possessing a definite chemical structure that gives it a unique set of physical properties. Most rocks are aggregates composed of two or more.

Compaction

occurs when the weight of overlying materials compresses the deeper sediments.

hydrothermal metamorphism

occurs where hot, ion-rich fluids circulate through rock and cause chemical alteration of the constituent minerals. Most ____ alteration occurs along the oceanic ridge system where sea-water migrates through hot oceanic crust and chemically alters newly formed basaltic rocks

continental margins, deep-ocean basins, and oceanic ridges.

ocean floor is divided into three major topographic units.

Uniformitarianism

one of the fundamental principles of modern geology advanced by James Hutton in the late 1700s, states that the physical, chemical, and biological laws that operate today have also operated in the geologic past. The idea is often summarized as "The present is the key to the past." Hutton argued that processes that appear to be slow-acting could, over long spans of time, produce effects that are just as great as those resulting from sudden catastrophic events

Rock Cycle

one of the many cycles or loops of the Earth system in which matter is recycled. It illustrates the origin of the three basic rock groups and the role of various geologic processes in transforming one rock type into another.

Composite cones

or stratovolcanoes, are large, nearly symmetrical structures built of interbedded lavas and py¬roclastic deposits. _______cones produce some of the most violent volcanic activity. Often associated with a vio¬lent eruption is a nuee ardente, a fiery cloud of hot gases in¬fused with incandescent ash that races down steep volcanic slopes. Large _____ cones may also generate a type of mudflow known as a lahar.

Sedimentary environments

places where sediment accumulates. They are grouped into continental, marine, and transitional (shoreline) environments. Each is charac¬terized by certain physical, chemical, and biological con¬ditions. Because sediment contains clues about the environment in which it was deposited, sedimentary rocks are important in the interpretation of Earth's history.

Plate tectonics theory

provides a comprehensive model of Earth's internal workings. It holds that Earth's rigid outer lithosphere consists of several segments called plates that are slowly and continually in motion relative to one anoth¬er. Most earthquakes, volcanic activity, and mountain build¬ing are associated with the movements of these plates.

Diagenesis

refers to all of the physical, chemical, and bio¬logical changes that occur after sediments are deposited and during and after the time they are turned into sedi¬mentary rock. Burial promotes ___. ____ in¬cludes lithification.

Lithification

refers to the processes by which unconsolidated sediments are transformed into solid sedimentary rock. Most sedimentary rocks are ____ by means of compaction and/or cementation.

Historical geology

seeks to understand the origin of Earth and its development through time.

Catastrophism

states that earth's landscapes developed over short time spans primarily as a result of great catastrophes

Regional metamorphism

takes place at con¬siderable depths over an extensive area and is associated with the process of mountain building. A gradation in the degree of change usually exists in association with ____ metamorphism, in which the intensity of metamorphism (low- to high-grade) is reflected in the texture and miner¬alogy of the rocks. In the most extreme metamorphic envi¬ronments, rocks called migmatites fall into a transition zone somewhere between "true" igneous rocks and "true" meta¬morphic rocks.

The texture of an igneous rock refers to the overall appear¬ance of the rock based on the size and arrangement of its in¬terlocking crystals. The most important factor affecting texture is the rate at which magma cools. Common igneous rock textures include aphanitic, with grains too small to be distinguished without the aid of a microscope; phaneritic, with intergrown crystals that are roughly equal in size and large enough to be identified with the unaided eye; porphyritic, which has large crystals (phenocrysts) interbedded in a matrix of smaller crystals (groundmass); and glassy.

texture of an igneous rock? what it refers to, what affects it, and common ones?

Lithosphere

the cool, rigid outermost layer that averages about 100 kilometers think.

Weathering

the disintegration and decomposition of rock at or near the Earth's surface

Batholiths

the largest intrusive igneous bodies, frequently make up the cores of mountains, as ex¬emplified by the Sierra Nevada.

Cementation

the most important process by which sedi¬ments are converted to sedimentary rock, occurs when sol¬uble cementing materials, such as calcite, silica, and iron oxide, are precipitated onto sediment grains, fill open spaces, and join the particles.

Mechanical weathering

the physical breakup of rock by frost wedging, salt crystal growth, unloading and biologic activity.

soil

the portion of regolith (rock and mineral fragments) that is a combination of mineral and organic matter, water, and air.

Erosion

the removal of material by wind, water, or ice.

Asthenosphere

the solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it

Mass Wasting

the transfer of rock material downslope by gravity.

Isotopes

variants of the same element. Some are unstable and disintegrate naturally through a process called radioactivity. Also, it's atoms of the same element that have different numbers of neutrons

Cinder cones

volcano. have steep slopes composed of pyroclastic ma¬terial

Magma originates from essentially solid rock of the asthenosphere. In addition to a rock's composition, its tem¬perature, depth (confining pressure), and water content de¬termine whether it exists as a solid or liquid.

what determines whether magma exists as a solid or liquid?