True or False
( ) Basaltic magmas are produced by partial melting of the Earth's crust along rift zones. ( ) Silicic magmas are produced most commonly by fractional crystallization of basaltic magma. ( ) The composition of a partial melt will always be the same as the solid rock from which it formed. ( ) Rhyolite and granite have the same chemical composition but different textures. ( ) The degree of volcanic hazard is highest with silicic magmas because they are extremely hot and fluid.
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( ) Rock competency is independent of strain rate; ( ) Rocks that deform by brittle fracture rather than ductile deformation exhibit incompetent behaviour; ( ) Rocks are stronger in compression than extension; ( ) Flow folding occurs at relatively low pressures and temperatures during brittle deformation; ( ) Competency influences how rocks are folded or faulted during deformation.
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Weathering: ( ) forms minerals that are relatively unstable at the Earth's surface; ( ) decrease the moisture content and porosity of rocks; ( ) produces both soluble and insoluble substances; ( ) combines with erosion to change the shape of landscapes over geologic time; ( ) decreases the density and strength of rocks.
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Is it true or false that perthite structure in feldspars provides evidence for the following? ( ) deformation; ( ) slow cooling; ( ) Bowen's Reaction Series; ( ) two stages of cooling; ( ) intergrowth of Na and K feldspar phases.
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Which of the following statements about deformation fabrics are true and which are false? ( ) Lineations are planar deformation fabrics often seen in metamorphic rocks; ( ) Intersection lineations often form along the intersection of bedding and foliation; ( ) Mineral lineations are usually defined by platy minerals such as muscovite; ( ) Cleavage often forms parallel to a fold axis; ( ) Cleavage vergence is used to establish the location of fold hinges with respect to specific outcrops.
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Which of the following statements about joints are true and which are false? ( ) Joints are fractures or cracks with observable displacement. ( ) Joints tend to be closely spaced and have a regular orientation. ( ) Joints influence the location and extent of both physical and chemical weathering. ( ) Joints are too narrow for minerals to precipitate within them and form veins. ( ) Volcanic rocks do not develop cooling joints as they cool too quickly.
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( ) Normal faults are typical of extensional environments and involve the upwards movement of the hanging wall relative to the footwall. ( ) Movement along reverse faults can result in significant crustal thickening. ( ) Thrust faults are low angle reverse faults that may involve large displacements. ( ) Listric faults are a type of normal fault that become steeper with depth. ( ) The repetition or omission of rock units is an indication of the possible presence of a fault.
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( ) Weathering results in the formation of non-silicate minerals only. ( ) Quartz, feldspar and clays make up the bulk of the material produced by the erosion of pre-existing rocks. ( ) The maturity of sediments and clastic sedimentary rocks decreases as the number of different minerals present increases. ( ) The maturity of sediments and clastic sedimentary rocks increases with the increasing amount of time that the sedimentary particles spend in a transport medium. ( ) Landslides and slips are most likely to occur when bedding planes in sedimentary rocks are perpendicular to the angle of natural or excavated slopes
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Which of the following statements about ore deposits are true and which are false? ( ) Heat from igneous intrusions is often the driving force for convective circulation of groundwater or seawater in hydrothermal systems; ( ) Banded iron formations are a type of iron ore that formed in the distant past when the atmosphere contained much more oxygen than today; ( ) Diamond deposits in kimberlite pipes are a good example of sedimentary ore formation; ( ) Placer deposits involve the concentration of heavy minerals by water; ( ) Precipitation of aluminium oxides and hydroxides from weathering solutions in the upper part of weathering profiles may form bauxite deposits.
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( ) Calcite is the principal mineral in limestone and marble. ( ) The formation of magnetite (Fe3O4) rather than hematite (Fe2O3) is favoured by a more oxidizing environment; ( ) Sulfides are a major phase in hydrothermal ore deposits but also occur as accessory minerals in igneous and metamorphic rocks; ( ) Chemical bonding in sulfides is dominantly ionic and may include metal-sulfur, metal-semimetal and sulfur-sulfur bonds; ( ) Quartz (SiO2) is not considered to be an oxide mineral.
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( ) Joints are fractures or cracks without observable displacement. ( ) Jointing usually creates slickensides. ( ) Joints influence the location and extent of both physical and chemical weathering. ( ) Joints can act as conduits for the infiltration, circulation and discharge of meteoric water. ( ) Plutonic rocks do not develop cooling joints as they cool too slowly.
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( ) Silicic magmas have a higher viscosity, are lower in temperature and have a higher volatile content than basaltic magmas. ( ) Pyroclastic textures result from a combination of explosive fragmentation and rapid cooling during eruption. ( ) Basaltic magmas are the result of partial melting of the Earth's core. ( ) Silicic magmas are most commonly produced by partial melting of the Earth's mantle along rift zones. ( ) The composition of a partial melt will always be the same as the solid rock from which it is forming.
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( ) Quartz is more stable at the Earth's surface than plagioclase; ( ) Scree consists of large rock fragments that accumulate on steep slopes as the result of physical weathering; ( ) Dissolution of calcite is a key process in physical weathering; ( ) The formation of inselbergs is related to joint spacing; ( ) The rates of chemical and physical weathering are little affected by climatic Variations.
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( ) Many ore deposits are linked with magmatic systems that formed along plate boundaries; ( ) Many ore deposits are closely linked with hydrothermal systems; ( ) Chromite ores are a common example of sedimentary ore formation; ( ) Placer deposits involve the concentration of heavy minerals by water. ( ) Precipitation of aluminium oxides and hydroxides from weathering solutions in the upper part of weathering profiles may form bauxite deposits.
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Which of the following statements about soils are true and which are false? ( ) The rate of soil accumulation is mostly a reflection of climate; ( ) The layers of a stratified weathering profile are known as soil horizons; ( ) The consistency of soil is largely governed by water content; ( ) Flocculated fabrics in cohesive soils are weaker than dispersed fabrics; ( ) Well-graded soils contain a narrow range of particle sizes.
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( ) Grain-size is the main criterion for classifying clastic sedimentary rocks. ( ) Quartz, feldspar and clays make up the bulk of the material produced by the erosion of pre-existing rocks. ( ) The maturity of sediments and clastic sedimentary rocks increases as the number of different minerals present decreases. ( ) The maturity of sediments or sedimentary rocks increases as the proportion of minerals prone to chemical weathering decreases. ( ) Landslides and slips are most likely to occur when bedding planes in sedimentary rocks are perpendicular to the angle of natural or excavated slopes
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( ) Mid-ocean ridges are areas of crustal extension; ( ) Transform plate boundaries are characterized by strike-slip faulting; ( ) Subduction zones can generate large earthquakes; ( ) Mid-ocean ridges are characterized by normal faulting; ( ) Most tectonic plates have fixed positions.
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