Geology Test 1 – Dalman – Flashcards

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Geology
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the science that examines Earth, its form and composition, and the changes that it has undergone and is undergoing
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physical geology
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a major division of geology that examines the materials of Earth and seeks to understand the processes and forces acting beneath and upon Earth's surface
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historical geology
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a major division of geology that deals with the origin of Earth and its development through time. Usually involves the study of fossils and their sequence in rock beds.
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catatrophism
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the concept that Earth was shaped by catastrophic evens of a short-term nature.
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uniformitarianism
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the concept that the processes that have shaped earth in the geologic past are essentially the same as those operating today
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hypothesis
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a tentative explanation that is then tested to determine if it is valid
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theory
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a well tested and widely accepted view that explains certain observable facts.
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hydrosphere
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the water portion of our planet; one of the traditional subdivisions of earth's physical environment
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atmosphere
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the gaseous portion of a planet, the planets envelope of air. one of the traditional subdivisions of earth's physical environment.
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biosphere
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the totality of life-forms on earth
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geosphere
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the solid earth; on of earth's four basic spheres
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system
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a group of interacting or independent parts that form a complex whole
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nebular theory
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a model for the origin of the solar system that supposes a rotating nebula of dust and gases that contracted to form the Sun and planets
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solar nebula
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the cloud of interstellar gas and/or dust from which the bodies of our solar system formed
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crust
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the very thin, outermost layer of earth
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mantle
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one of earths compositional layers. the solid rocky shell that extends from the base of the crust to the depth of 2900 kilometers (1800 miles)
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lithosphere
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the rigid outer layer of earth, including the crust and upper mantle
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athenosphere
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a subdivision of the mantle situated below the lithosphere. This zone of weak material exists below a depth of about 100 kilometers (60 miles) and in some regions extends as deep as 700 kilometers (430 miles). The rock within this zone is easily deformed
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core
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the innermost layer of earth. it is thought to be largely an iron-nickle alloy, with minor amounts of oxygen, silicon, and sulfur
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outer core
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a layer beneath the mantle about 2270 kilometers (1410 miles) thick, which as the properties of a liquid.
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inner core
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the solid innermost layer of earth, about 1216 kilometers (754) in radius
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craton
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the part of the continental crust that has attained stability; that is, it has not been affected by significant tectonic activity during the Phanerozoic eon. It consists of the shield and the stable platform
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shield
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a large, relatively flat expanse of ancient igneous and metamorphic rocks within the craton
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continental margin
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the portion of the seafloor that is adjacent to the continents. it may include the continental shelf, continental slope, and continental rise.
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continental shelf
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the gently sloping submerged portion of the continental margin, extending from the shoreline to the continental slope
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continental slope
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the steep gradient that leads to the deep-ocean floor and marks the seaward edge of the continental shelf
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continental rise
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the gently sloping surface at the base of the continental slope
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deep ocean basin
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the portion of the seafloor that lies between the continental margin ad the oceanic ridge system. This region comprises almost 30 precent of the Earth's surface
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abyssal plain
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a very level area of the deep-ocean floor, usually lying at the foot of the continental rise.
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deep ocean trench
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a narrow, elongated depression of the seafloor
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sea mount
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an isolated volcanic peak that rises at least 1000 meters (3300 feet) above the deep-ocean floor
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rock cycle
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a model that illustrates the origin of the three basic rock types and the interrelatedness of earth materials and processes
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igneous rock
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rock formed from the crystallization of magma
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sediment
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unconsolidated particles created by the weathering and erosion of rock by chemical precipitation from solution in water, or from the secretions of organisms, and transported by water, wind, or glaciers.
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sedimentary rock
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rock formed from the weathered products of preexisting rocks that have been transported, deposited, and lithified
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metamorphic rock
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rock formed by the alteration of preexisting rock deep within Earth(but still in the solid state) by heat, pressure, and/or chemically active fluids.
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continental drift
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a hypothesis, credited largely to alfred wegner, which suggested that all present continents once existed as a single supercontinent. Further, beginning about 200 million years ago, the super continent began breaking into smaller continents, which then 'drifted' to their present positions.
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supercontinent
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a large landmass that contains all, or nearly all, of the existing continents.
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Pangea
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the proposed supercontinent that 200 million years ago, began to break apart and form the present landmasses
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lithosphere
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the rigid outer layer of Earth, including the crust and upper mantle
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lithospheric plate
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a coherent unit of earths rigid outer layer that includes the crust and upper unit
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divergent plate boundary
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a boundary in which two plates move apart, resulting in upwelling of material from the mantle to create new seafloor.
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rift valley
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a long, narrow trough bounded by normal faults. It represents a region where divergence is taking place
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sea floor spreading
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a hypothesis, first proposed in the 1960's by harry hess, which suggested that new oceanic crust is produced at the crests of mid-ocean ridges, which are the sites of divergence.
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continental rift
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a linear zone along which continental lithosphere stretches and pulls apart. Its creation may mark the beginning of a new ocean basin.
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convergent plate boundary
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a boundary in which two plates move together, resulting in oceanic lithosphere being thrust beneath an overriding plate, eventually to be reabsorbed into the mantle. It can also involve the collision of two continental plates to create a mountain system.
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deep ocean trench
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a narrow, elongated depression of the seafloor.
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partial melting
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the process by which most igneous rocks melt. Since individual minerals have different melting points, most igneous rocks melt over a temperature range of a few hundred degrees. If the liquid is squeezed out after some melting has occurred, a melt with a higher silica content results.
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continental volcanic arc
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mountains formed in part by igneous activity associated with the subduction of oceanic lithosphere beneath a continent. Examples include the ANdes and the Cascades
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volcanic island arc
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a chain of volcanic islands generally located a few hundred kilometers from a trench where there is active subduction of one oceanic plate beneath another.
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transform fault boundary
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a boundary in which two plates slide past one another without creating or destroying lithosphere
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fracture zone
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a linear zone of irregular topography on the deep-ocean floor that follows transform faults and their inactive extensions.
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mantle plume
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a mass of hotter-than-typical mantle material that ascends toward the surface, where it may lead to igneous activity. These plumes of solid yet mobile material may originate as deep as the core-mantle boundary.
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hot spot
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a concentration of heat in the mantle, capable of producing magma that, in tun, extrudes onto earths surface. The intraplate volcanism that produced the Hawaiian Islands is one example
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hot-spot track
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a chain of volcanic structures produced as a lithospheric plate moves over a mantle plume.
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curie point
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the temperature above which a material loses its magnetization
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paleomagnatism
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the natural remnant magnetism in rock bodies. The permanent magnetization acquired by rock that can be used to determine the location of the magnetic poles and the latitude of the rock at the time it became magnetized.
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magnetic reversal
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a change in Earth's magnetic field from normal to reverse or vice versa
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normal polarity
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a magnetic field the same as that which presently exists
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reverse polarity
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a magnetic field opposite that which presently exists
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magnetometer
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a sensitive instrument used to measure the intensity of Earth's magnetic field at various points.
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convection
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the transfer of heat by the mass movement or circulation of a substance
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mineralogy
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the study of minerals
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mineral
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a naturally occurring, inorganic crystalline material with a unique chemical structure
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rock
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a consolidated mixture of minerals
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atom
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the smallest particle that exists as an element
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nucleus
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the small, heavy core of an atom that contains all of its positive charge and most of its mass
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proton
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a positively charged subatomic particle found in the nucleus of an atom
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neutron
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a subatomic particle found in the nucleus of an atom. The neutron is electrically neutral, with a
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electron
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a negatively charged subatomic particle that has a negligible mass and is found outside an atom's nucleus.
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valence electron
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the electrons involved in the bonding process; the electrons occupying the highest principal energy level of an atom
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atomic number
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the number of protons in the nucleus of an atom
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element
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a substance that cannot be decomposed into simpler substances by ordinary chemical or physical means.
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periodic table
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an arrangement of the elements in which atomic number increases from the left to right and elements with similar properties appear in columns called families or groups
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octet rule
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a rule which states that atoms combine in order that each may have the electron arrangement of a noble gas (that is, the outer energy level contains eight neutrons)
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chemical bond
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a strong attractive force that exists between atoms in a substance. It involves the transfer or sharing of electrons that allows each atom to attain a full valence shell.
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ion
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an atom or a molecule that possesses an electrical charge
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ionic bond
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a chemical bond between to oppositely charged ions that is formed by the transfer of valence electrons from one atom to the other.
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covalent bond
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a chemical bond produced by the sharing of electrons
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metallic bond
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a chemical bond that is present in all metals that may be characterized as an extreme type of electron sharing in which the electrons move freely from atom to atom.
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luster
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the appearance or quality of light reflected from the surface of a mineral
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color
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a phenomenon of light by which otherwise identical objects may be differentiated
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streak
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the color of a mineral in powdered form.
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crystal shape (habit)
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refers to the common or characteristic shape of a crystal or an aggregate of crystals
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hardness
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a minerals resistance to scratching and abrasion
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Mohs scale
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a series of 10 minerals used as a standard in determining hardness
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cleavage
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the tendency of a mineral to break along planes of weak bonding.
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fracture
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any break or rupture in rock along which no appreciable movement has taken place.
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tenacity
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describes a minerals toughness or resistance to breaking or deforming
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density
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a property of matter defined as mass per unit volume
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specific gravity
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the ratio of a substances weight to the weight of an equal volume of water
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rock forming mineral
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the relatively few minerals that make up most of the rocks in earth's crust
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silicate
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any one of numerous minerals that have the silicon-oxygen tetrahedron as their basic structure
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silicon-oxygen tetrahedron
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a structure composed of four oxygen atoms surrounding a silicon atom that constitutes the basic building block of silicate minerals
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light silicate
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a silicate mineral that lacks iron and/or magnesium. Light silicates are generally lighter in color and have lower specific gravities than dark silicates.
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dark silicate
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a silicate mineral that contains ions of iron and/or magnesium in its structure. Dark silicates are dark in color and have a higher specific gravity than nonferromagnesian
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renewable
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a resource that is virtually inexhaustible or that can be replenished over relatively short time spans
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non renewable
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a resource that forms or accumulates over such long time spans that it must be considered as fixed in total quantity
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mineral resource
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all discovered and undiscovered deposits of a useful mineral that can be extracted now or at some time in the future
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ore deposit
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an accumulation of ore. This is distinct from a mineral resource as defined by the mineral resource classification criteria. An ore deposit is one occurrence of a particular ore type.
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magma
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a body of molten rock found at depth, including any dissolved gases and crystals.
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lava
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magma that reaches earth's surface
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melt
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the liquid portion of magma excluding the solid crystals
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volatile
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gaseous components of magma dissolved in the melt. Volatiles will readily vaporize (form a gas) at surface pressures
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crystallization
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the formation and growth of a crystalline solid from a liquid or gas
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intrusive igneous rock
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igneous rock that formed below earths surface
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extrusive igneous rock
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igneous rock that forms at the earths surface
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granitic composition
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a compositional group of igneous rocks indicating the rock is composed almost entirely of light-colored silicates
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basaltic composition
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a compositional group of igneous rocks indicating the rom is composed almost entirely of light-colored silicates compositional rout of igneous rocks indicating that the rock contains substantial dark silicate minerals and calcium-rich plagioclase feldspar
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andesitic (intermediate) composition
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a compositional group of igneous rocks that contains at least 25 precent dark silicate minerals. The other dominant mineral is plagioclase feldspar.
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ultra mafic
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a compositional group of igneous rocks containing mostly olivine and pyroxene
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texture
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the size, shape, and distribution of the particles that collectively constitute a rock
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aphanitic
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a texture of igneous rocks in which the crystals are too small for individual minerals to be distinguished without the aid of a microscope
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phaneitic
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an igneous rock texture in which the crystals are roughly equal in size and large enough so the individual minerals can be identified without the aid of a microscope
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prophyritic
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an igneous rock texture characterized by two distinctly different crystal sizes. The larger crystals are called phenocrysts, whereas the matrix of smaller crystals is termed the groundmass
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pheoncryst
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a conspicuously large crystal embedded in a matrix of finer-grained crystals
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ground mass
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the matrix of smaller crystals within an igneous rock that has porphyritic texture
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porphyry
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an igneous rock that has a porphyritic texture
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vesicular texture
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a term applied to aphanitic igneous rocks that contain many small cavities called vesicles
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glassy texture
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a term used to describe the texture of certain igneous rocks, such as obsidian, that contain no crystals
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pyroclastic texture
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an igneous rock texture resulting from the consolidation of individual rock fragments that are ejected during a violent volcanic eruption
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pumice
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a light-colored, glassy vesicular rock commonly having a granitic composition
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basalt
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a fine grained igneous rock of mafic composition
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geothermal gradient
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the gradual increase in temperature with depth in the crust. The average is 30 degrees C per kilometer in the upper crust
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decompression melting
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melting that occurs as rock ascends due to a drop in confining pressure
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Bowens reaction series
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a concept proposed by N.L. Bowen that illustrates the relationships between magma and the minerals crystallizing from it during the formation of igneous rocks.
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crystal settling
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a process that occurs during the crystallization of magma, in which the earlier formed minerals are denser than the liquid portion and settle to the bottom of the magma chamber
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magmatic differentiation
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the process of generating more than one rock type from a single magma
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assimilation
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in igneous activity, the process of incorporating country rock into a magma body
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xenolith
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an inclusion of unmelted country rock in an igneous pluton
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magma mixing
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the process of altering the composition of a magma through the mixing of material from another magma body
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partial melting
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the process by which most igneous rocks melt. since individual minerals have different melting points, most igneous rocks melt over a temperature range of a few hundred degrees. If the liquid is squeezed out after some melting has occurred, a melt with a higher silica content results.
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intrusion (pluton)
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a structure that results from the emplacement and crystallization of magma beneath the surface of earth
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tabular
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describing a feature such as an igneous pluton that has two dimensions that are much longer than the third.
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massive
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an igneous pluton that is not tabular in shape
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discordant
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a term used to describe plutons that cut across existing rock structures, such as bedding planes
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concordant
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a term used to describe intrusive igneous masses that form parallel to the bedding of the surrounding rock
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dike
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a tabular-shaped intrusive igneous feature that cuts through the surrounding rock
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sill
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a tabular igneous body that was intruded parallel to the layering of preexisting rock
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columnar joining
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a pattern of cracks that forms during cooling of molten rock to generate columns
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batholith
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a large mass of igneous rock that formed when magma was emplaced at depth, crystallized, and subsequently exposed by erosion
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stock
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a pluton similar to but smaller than a batholith
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laccolith
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a massive igneous body intruded between preexisting strata
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pegmatite
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a very coarse-grained igneous rock (typically granite) commonly found as a dike associated with a large mass of plutonic rock that has smaller crystals. Crystallization in a water-rich environment is believed to be responsible for the very large crystals
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vein deposit
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a mineral that fills a fracture or fault in a host rock. Such deposits have a sheetlike, or tabular, form.
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disseminated deposit
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any economic mineral deposit in which the desired mineral occurs as scattered particles in the rock but in sufficient quantity to make the deposit an ore.
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viscosity
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a measure of a fluids resistance to flow
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eruption column
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buoyant plumes of hot, ash-laden gases that can extend thousands of meters into the atmosphere
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Aa flow
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a type of lava flow that has a jagged, blocky surface
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pahoehe flow
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a lava flow with a smooth ropy surface
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lava tube
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a tunnel in hardened lava that acts as a horizontal conduit for lava flowing from a volcanic vent. Lava tubes allow fluid lavas to advance great distances.
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block lava
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lava that has a surface of angular blocks associated with material having andesitic and rhyolitic compositions.
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pillow lava
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basaltic lava that solidifies in an underwater environment and develops a structure that resembles a pile of pillows
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volatiles
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gaseous components of magma dissolved in the melt. Volatiles will readily vaporize (from a gas) at surface pressures
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pyroclastic materials
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the volcanic rock ejected during an eruption. Pyroclastic's include ash, bombs and blocks.
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scoria
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vesicular ejecta that is the product of basaltic magma
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conduit
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a pipeline opening through which magma moves toward Earth's surface. It terminates at a surface opening called a vent
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vent
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the surface opening of a conduit or pipe
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volcanic cone
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a cone-shaped structure built by a successive eruptions of lava and/or pyroclastic materials
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crater
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the depression at the summit of a volcano or a depression that is produced by a meteorite impact
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parasitic cone
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a volcanic cone that forms on the flank of a larger volcano
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shield volcano
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a broad, gently sloping volcano built from fluid basaltic lavas
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cinder cone (scoria cone)
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a rather small volcano built primarily of ejected lava fragments that consist of mostly pea-to-walnut size lapilli
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composite volcano (stratovolcano)
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a volcano composed of both lava flows and pyroclastic material
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pyroclastic flow (nuee ardente) lahar
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a highly heated mixture, largely of ash and pumice fragments, that travels down the flanks of a volcano or along the surface of the ground.
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aerosol
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tiny solid and liquid particles suspended in the atmosphere
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caldera
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a large depression typically caused by collapse or ejection of the summit area of a volcano
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fissure
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a crack in rock along which there is a distinct separation
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fissure eruption
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an eruption in which lava extruded from narrow fractures or cracks in the crust
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flood basalt
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flows of basaltic lava that issue from numerous cracks or fissures and commonly cover extensive areas to thicknesses of hundreds of meters
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lava dome
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a bulbous mass associated with an old-age volcano, produced when thick lava is slowly squeezed from the vent. Lava domes may act as plugs to deflect subsequent gaseous eruptions
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volcanic neck (plug)
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an isolated, steep-sided, erosional remnant consisting of lava that once occupied the vent of a volcano
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pipe
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a vertical conduit through which magmatic materials have passed
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ring of fire
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the zone of active volcanoes surrounding the pacific ocean
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continental island arc
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mountains formed in part by igneous activity associated with the subduction of oceanic lithosphere beneath a continent. Examples include the Andes and the Cascades
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intraplate volcanism
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igneous activity that occurs within a tectonic plate, away from plate boundaries
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mantle plume
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a mass of hotter-than-typical mantle material that ascends toward the surface, where it may lead to igneous activity. These plumes of solid yet mobile material may originate as deep as the core-mantle boundary.
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