Chapter 20 science
Rank the magma types in order of increasing (low to high) silica content (a) basaltic, (b) granitic, (c) andesitic.
(A) basaltic (C) andesitic (B) granitic
Rank hardest to softest of these minerals: (a)corundum (b)feldspar (c)fluorite (d)gypsum
(A) corundum (B) feldspar (C) fluorite (D) gypsum
Rank these minerals in order of partial melting: (a) quartz, (b) feldspar, (c) olivine. (d) pyroxene
(A) quartz (B) feldspar (D) pyroxene (C) olivine
Rank these rock-forming minerals from most abundant to least abundant: (a) silicates, (b) carbonates, (c) sulfates, (d) oxides.
(A) silicates (B) carbonates (C) sulfates (D) oxides
Name the rock for each statement then rank them from low to high grade: (a) foliated rock, sometimes derived from granite (b) foliated rock, possessing c ) foliated rock containing about 50 % platy excellent rock cleavage: generally used in making blackboards minerals . named according to the major minerals in the rock
(B) (C) (A)
Rank most useful to least useful: (a)color (b)hardness (c)streak (d)cleavage
(B) hardness (D) cleavage (C) streak (A) color
Rank the following stages of sedimentary rock formation from first to last: (a)erosion (b)lithification (c)weathering (d)deposition
(C) weathering (A) erosion (D) deposition (B) lithification
Rank first to last, the episodes that brought about Earth's uneven distribution of elements: (a)gravitational attraction (b)radioactive decay heating (c)density segregation (d)impact heating
(D) Impact heating (A) gravitational attraction (B) radioactive decay (C) density segregation
What is the difference between a dike and a sill?
A dike intrudes across sedimentary layers, and a sill intrudes between sedimentary layers.
What is a magma chamber called after the conduit has solidified and been exposed by erosion?
Batholith
What do freeze-thaw and salt weathering have in common?
Both freeze-thaw and salt weathering require rain and force rocks apart physically
Why are mineral bands in metamorphic rocks light and dark colored?
Dark minerals rich in iron and magnesium separate from light minerals rich in silica and aluminum.
In general, why does Earth's crust sit on top of the mantle ?
Earth's crust is less dense than the mantle.
How are felsic magmas formed?
Heat fro m the mantle melts part of the lower crust
Why do bands of minerals form when rocks are put under normal stress?
Minerals dissolve, atoms migrate to new locations, and minerals reform.
Could metamorphic rocks reach the surface of a planet without rock-upliting processes?
No, metamorphic rocks must be uplifted and exposed by erosion.
How are metamorphic rocks formed?
Preexisting rock is altered through heat and pressure.
How do mafic volcanic rocks get to Earth's surface?
Pressure from overlying crust forces mantle magmas through cracks to Earth's surface. These magmas erupt out of volcanoes, cool, and solidify into rock.
Why are volcanic rocks often exposed at Earth's surface as hills,ridges, and mountains surrounded by areas of lower elevation?
Volcanic rocks are often more resistant to erosion than surrounding rock
Why does water frozen in the cracks of a rock help to break down the rock?
Water expands when frozen and physically forces the rock apart
In general, when will melted rock in the mantle rise?
almost always
What is foliation?
banding in metamorphic rocks that results from the reorientation of minerals
Where do most metamorphic rocks form?
between a few and many kilometers beneath Earth's surface
Which processes result in mineral flattening during metamorphism?
dissolution followed by crystallization
What would you call a granite that has undergone metamorphism and now exhibits foliation?
gneiss
What lies underneath volcanic features at Earth's surface?
magma chambers and volcanic conduits
Which two rock types would you expect to see sitting next to each other after a very long period characterized by only uplift and erosion?
metamorphic and sedimentary rocks
If a rock contains mineral A 30 % silica ) and mineral B ( 25 % silica which would melt last as temperature increases ?
mineral B
How will minerals orient when a rock is put under shear stress?
parallel to the direction of the shear stress
How will foliation in continental metamorphic rocks formed during subduction be oriented?
perpendicular to the direction of plate movement
How will minerals grow when a rock is put under normal stress?
perpendicular to the direction of the greatest stress
How will minerals orient when a rock is put under normal stress?
perpendicular to the direction of the greatest stress
Do metamorphic rocks look like the preexisting rock from which they form?
sometimes, but not always
What is salt weathering?
the formation of minerals in rock cracks during the evaporation of s alty water, forcing rock apart
What is rock texture?
the way a rock looks
How do metamorphic rocks reach Earth's surface?
through removal of overfying rocks
What is a volcanic conduit called after the conduit has solidified and been exposed by erosion?
volcanic neck
When will magma rise to Earth's surface?
when the magma is less dense than adjacent rock