Geology chapter 4.

a dike is_________.

a sheetlike intrusion that cuts across preexisting layers.

a sill is ________

a sheetlike intrusion that lies parallel to surrounding laters of sedimentary rock.

if a body of magma becomes more felsic, its viscosity will ______.

increase.

A bob-like igneous rock body that has cooled beneath the surface of Earth is called______.

A pluton

igneous rocks _______.

A. are formed through the freezing melt. B. can be produced at the surface of Earth as well as deep below the surface C. are most common type of rocks within earth. >>D. ALL OF THE ABOVE <<

Obsidian ________.

A. is volcanic glas B. possess conchoidal fracture C. typically is felsic in composition >>D. ALL OF THE ABOVE <<<

most commonly, felsic igneous rock _______.

Are lighter in color than mafic rocks.

all other factors being equal, intrusive rocks that form deep within earth _______ than intrusive rock that cool near the surface.

Cool more slowly

If the volatile content of magma is increased, its viscosity will______.

Decrease.

when rock is melted within Earth, typically the entire volume of rock is transformed from a solid state to a liquid. (true of false).

FALSE

which type of magma has the greatest silica content?

Felsic

when magma crystallizes _______ are formed.

Intrusive igneous rocks.

The difference between Lava and magma is that _______.

Magma is found beneath the Earth's surface, whereas lava has reached the surface.

Very early in the Earth;s history, it was so hot that the surface was likely entirely molten (true or false)

TRUE

as compared to coarse-grained igneous rock, all fine-grained igneous rocks _____.

cool and solidify more slowly.

Volatiles refer to substances that _________.

have a tendency to evaporate and are stable as gases.

Important volatiles in magmas include_____.

water and carbon dioxide.