Geology Test 1-2
the removal of detritus from weathered rock at an outcrop is termed
erosion
a famous example of hot-spot volcanism occurs at
hawaii
If a body of magma becomes more felsic, its viscosity will
increase
(T/F) asymmetric ripples are indicative of unidirectional flow, whereas symmetric ripples are indicative to flow in multiple directions
true
obsidian, shown below,
all of the above are correct-- is volcanic glass, typicalls in felsic composition, posess conchoidal fracture
if a geologist found preserved mud cracks, he or she could conclude that the environment in which they formed
all of the above are correct-- was once covered in wet mud, was once covered in hevagonal plates with curled up edges, has been covered in sediment
ripples, dunes, and cross bedding are sedimentary structures that can be used to determine
all of the above are correct-- wind direction, current direction, past environements
which of the following is NOT a factor controlling the cooling rate of magma
all of the above are factors--- depth of intrusion, shape and size of magma body, presence of circulating groundwater
a clastic rock comprised of sand-sized grains derived from the physical weathering of granite and containing a sizable proportion of feldspar is termed
arkose
which environment would most likely produce sedimentary deposits characterized by very well-sorted, very well-sounded grains that are nearly pure quartz
beach
cemented shells of marine organisms form which kind of sedimentary rock?
biochemical
biochemical limestones are dominated by carbonate mid and fragments of
calcitic and aragonitic skeletons of marine invertebrates
physical precipitation of gypsum die to evaporation of seawater produces which kind of sedimentary rock?
chemical
lithified detritus (breakdown products of preexisting rocks) forms which kind of sedimentary rock?
clastic
glacial till is composed of ___ sized particles
clay-to boulder
as compared to aphanitic igneous rocks, phaneritic rocks are
coarser grained
topset, foreset, and bottomset beds are indicative of
deltas
when limestone becomes chemically altered so that half of the calicium atoms are replaced by magnesium, the resultant rock is termed
dolostone
if you found tuff deposits at an ___ igneous setting, you could conclude that the lava had a ___ viscosity content
extrusive; high
large igneous provinces are formed by ___ which can flow tens to hundreds of kilometers
flood basalts
vesicles are a term used to describe a texture in ___ igneous rocks
glassy
a dike is a
intrusion formed within the magma chamber of a volcano
when magma crystallizes, ____ are formed
intrusive igneous rocks
volcanoes that do NOT occur along either present or emergent plate boundaries are associated with
mantle hot spots
chemical and biochemical rocks are classified primarily on the basis of
mineral composition
due to fractional crystallization and assimilation of surrounding host rock, most magmas that rise slowly through the crust chemically evolve to become
more felsic
if a body of magma is subjected to fractional crystallization, the rock that results is expected to be
more mafic than the magma
in Bowne's discontinuous reaction serious, the first mineral to crystallize form a mafic melt is
olivine
two major sources of energy, coal and oil shale, are considered ___ sedimentary rocks
organic
stopping by magmas occurs when
pieces of surrounding country rock are broken off and assimilated
bowen's continuous reaction series described the crystallization behavior of asingle mineral (with variable chemical composition), ______
plagioclase
a blob-like igneous rock body that has cooled beneath the surface of earth is
pluton
an igneous rock with a mixed texture of coarse grains (phenocrysts) surrounded by fine crystals (groundmass) is termed
porphyritic
pegmatites, which occur in dikes, are unusual among shallow intrusive rocks in that they
possess exceptionally coarse grains
the difference between breccia and conglomerate is that conglomerate
possesses more rounded grains than breccia
bombs, ash, and cinders are all examples of
pyroclastic debric
coarse-grained granite is most similar in mineral composition to fine-grained
rhyolite
mt. Kilimanjaro and the basin and range province are the result of
rifting
a sill is a
sheet-like intrusion that cuts across preexisting layers
in regard to the cooling of molten rock, a ___ volume and a ___ shape cools faster
smaller; pancake
an island volcanic arc occurs at
the Aleutian islands of alaska
stratification refers to
the development of layering within sedimentary rocks
a volcana emits ash, which falls from the sky, settles in layers, and is eventually cemented. the resulting rock is termed
tuff
graded beds tell a geologist that a
turbidity current deposited these beds, depositing coarser material first
if water is the transparent mechanism of sediment, the grain size of sedimentary deposits most closely indicates the
velocity of the water at the moment the sediment settled to the bottom
chemical weathering takes place most rapidly in environments that are ___ and ___
warm; wet
the breakdown of exposed rock into small fragments and dissolved ions is termed
weathering
ash and lava fragments that cascade down the sides of a volcano eventually settle and lithify to form ___
welded tuff
it is unsual for ___ to carry grains larger than sand
wind