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