Physical Science ES Chapter 20

Part B: What is the difference between a dike and a sill?

A dike intrudes across sedimentary layers, and a sill intrudes between sedimentary layers.

Mineral hardness depends on chemical bond strength. From hardest to softest, rank the following minerals: (a) corundum, (b) feldspar, (c) fluorite, (d) gypsum. Rank from hardest to softest. To rank items as equivalent, overlap them.

A, B, C, D

Rank these rock-forming minerals from most abundant to least abundant: (a) silicates, (b) carbonates, (c) sulfates, (d) oxides. Rank from most to least. To rank items as equivalent, overlap them.

A, B, C, D

In partial melting, rocks and minerals with a low melting temperature melt more easily. Rank these minerals in order of partial melting: (a) quartz, (b) feldspar, (c) olivine, (d) pyroxene. Rank from most to least. To rank items as equivalent, overlap them.

A, B, D, C

Rank the magma types in order of increasing (low to high) silica content: (a) basaltic, (b) granitic, (c) andesitic. Rank from least to most. To rank items as equivalent, overlap them.

A, C, B

Each of the following statements describes one or more characteristics of a particular metamorphic rock. 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 excellent rock cleavage; generally used in making blackboards (c) foliated rock containing about 50% platy minerals; named according to the major minerals in the rock. Rank from low to high. To rank items as equivalent, overlap them.

B, C, A

Most minerals can be identified by their physical properties. Rank the following properties used for mineral identification from most useful to least useful: (a) color, (b) hardness, (c) streak, (d) cleavage. Rank from most to least. To rank items as equivalent, overlap them.

B, D, C, A

Part C: What do freeze-thaw and salt weathering have in common?

Both freeze-thaw and salt weathering require rain and force rocks apart physically.

Rank the following stages of sedimentary rock formation from first to last: (a) erosion, (b) lithification, (c) weathering, (d) deposition. Rank from first to last. To rank items as equivalent, overlap them.

C, A, D, B

When Earth first formed, its elements were distributed evenly. Rank, from 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. Rank from first to last. To rank items as equivalent, overlap them.

D, A, B, C

Part F: 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.

Part D: In general, why does Earth's crust sit on top of the mantle?

Earth's crust is less dense than the mantle.

Part C: How are felsic magmas formed?

Heat from the mantle melts part of the lower crust.

Part E: Why do bands of minerals form when rocks are put under normal stress?

Minerals dissolve, atoms migrate to new locations, and minerals reform.

Part D: Could metamorphic rocks reach the surface of a planet without rock-uplifting processes?

No, metamorphic rocks must be uplifted and exposed by erosion.

Part A: How are metamorphic rocks formed?

Preexisting rock is altered through heat and pressure.

Part E: 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.

Part D: 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.

Part B: In general, when will melted rock in the mantle rise?

almost always

Part C: What is foliation?

banding in metamorphic rocks that results from the reorientation of minerals

Part E: What is a magma chamber called after the conduit has solidified and been exposed by erosion?

batholith

Part A: Where do most metamorphic rocks form?

between a few and many kilometers beneath Earth's surface

Part G: Which processes result in mineral flattening during metamorphism?

dissolution followed by crystallization

Part E: What would you call a granite that has undergone metamorphism and now exhibits foliation?

gneiss

Gold has a density of 19.3 g/cm3. A 5-gal pail of water (density of water = 1.0 g/cm3) has a mass of about 18.0 kg. What is the mass of a 5-gal pail of gold?

m =347 kg

Part A: What lies underneath volcanic features at Earth's surface?

magma chambers and volcanic conduits

Part C: 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

Part D: How will minerals orient when a rock is put under shear stress?

parallel to the direction of the shear stress

Part D: How will foliation in continental metamorphic rocks formed during subduction be oriented?

perpendicular to the direction of plate movement

Part B: How will minerals orient when a rock is put under normal stress?

perpendicular to the direction of the greatest stress

Part C: How will minerals grow when a rock is put under normal stress?

perpendicular to the direction of the greatest stress

Part B: Do metamorphic rocks look like the preexisting rock from which they form?

sometimes, but not always

Part B: What is salt weathering?

the formation of minerals in rock cracks during the evaporation of salty water, forcing rock apart

Part A: What is rock texture?

the way a rock looks

Part B: How do metamorphic rocks reach Earth's surface?

through removal of overlying rocks

Part C: What is a volcanic conduit called after the conduit has solidified and been exposed by erosion?

volcanic neck

Part A: When will magma rise to Earth's surface?

when the magma is less dense than adjacent rock