Exam 1 Geology

What does it mean if an igneous rock has an aphanitic texture?

The igneous rock exhibits mineral crystals too small to see with the naked eye.

in addition to viscosity, which of the following parameters has an influence on whether a volcanic eruption will be effusive or violent?

amount of gas in the magma

what are shield volcanoes generally made of?

basalt flows

which of the following types of lava will most likely lead to a volcanic eruption of an effusive nature?

basaltic

what is magma chamber called after the conduit has solidified and been exposed by erosion?

batholith

which of the following terms is best described as massive pluton?

batholith

minerals must be solid, have an orderly atomic structure, have a recognized chemical composition, be naturally occurring, and _______

be generally inorganic in origin

Batholiths are known to form of mountain ranges such as the Sierra Nevada. What is the implication of this observation?

because batholiths form deep within earth, the occurrence of one at the surface implies that it has since been uplifted Sandor the rocks above have been removed.

what causes a lack of cleavage in some minerals?

bonds of equal strength in all directions

which of the following are types of volcanoes?

cinder cone shield volcano composite volcano

which of the following is the volcanic feature in which magma rises through before it is released at the surface?

conduit

what is the term for a tabular igneous pluton that occurs in an orientation that is discordant with the bedding surfaces of adjacent sedimentary rocks?

dike

Which of the following environments would produce igneous rocks?

divergent boundaries convergent boundaries hot spots

what discourages minerals from achieving habit?

enclosed spaces

what type of magma erupts out of dome complexes?

felsic magma

the amount or quality of light that is reflected from a mineral surface is known as _____

luster

what lies underneath volcanic features at Earth's surface?

magma chambers and volcanic conduits

regardless of their size, most rocks are made up of ______

minerals

in general, how often do most cinder cones erupt?

most cinder cones erupt once

Intrusive and extrusive igneous rocks are classified based on what criteria?

How quickly the molten rock cools and crystallizes, and where this occurs with respect to Earth's surface.

What is streak?

The color of a powdered form of a mineral produced by rubbing it across a hard surface.

what is the term for a tabular igneous pluton that occurs in an orientation that is concordant with the bedding surfaces of adjacent sedimentary rocks?

sill

crystal habit is the shape that a mineral develops by the repetition of ______

the basic unit cell of a mineral

why are shield volcanoes wider than composite volcanoes?

the lava that flows out of shield volcanoes is more fluid than the lava that flows out of composite volcanoes

the subduction of oceanic crust under continental crust predominately produces which of the following types of volcanic eruption?

violent and explosive

what is a volcanic conduit called after the conduit has solidified and been exposed by erosion?

volcanic neck

Why are volcanic rocks often exposed to Earth's surface as hills, ridges, and mountains surrounded by areas of lower elevation?

volcanic rocks are often more resistant to prion than surrounding rock

igneous rocks are mainly composed of ______ minerals.

silicate

what is the range of shield volcano heigh

300 to 10,000 meters

what is the range of dome complex height?

500 to 2,000 meters

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 required to generate an igneous rock with a fine-grained texture?

A fine-grained texture is the product of rapid cooling and crystallization of lava.

which of the following objects has a size similar to that of lapilli?

A marble (15mm)

What causes the same mineral to occur in varieties that are different colors?

A small amount of impurities in the crystal structure.

what is cleavage?

Cleavage is the splitting of minerals along natural planes of weakness

Why is glass not considered a mineral?

Glass has a disorderly atomic structure.

How are igneous rock formed?

Igneous rocks are formed by the cooling and crystallization of molten rock.

what is one way a glassy texture forms?

Lava cools rapidly.

which of the following is true about magic igneous rocks?

Mafic igneous rocks are rich in Fe, Mg, and Ca.

Volcanic ash is best described as which of the following?

Microscopic pieces of rock ejected by a volcano

Which of the following textures describes an igneous rock with anomalously large crystals?

Pegmatitic

Which of the following textures indicates two stages of cooling and crystallization?

Porphyritic

what information do geologists use to classify volcanoes?

Shape and type of deposits

what does an igneous rock with a pyroclastic texture tell a geologist?

The rock was likely formed by a violent volcanic eruption.

what best describes mineral habit?

The shape a mineral grows into, given sufficient space.

which igneous composition contains mostly olivine crystals with minor amounts of pyroxene?

Ultramafic

Which of the following describes a texture containing bubble-shaped cavities?

Vesicular

while working in the field, you find a dike cutting across some sedimentary rocks. what grain size would you expect to find in this pluton?

fine-grained

Igneous rocks of felsic composition have _______ and ______ relative to magic igneous rocks.

greater silica; lower melting temperature

what is the basic foundation of Moh's hardness scale?

if a mineral scratches an object, then the mineral is harder than the object.

A phaneritic texture is characteristic of a(n)_____ igneous rock that cooled ________.

intrusive; below the surface

which of the following volcanic materials flows out of a volcanic vent?

lava

cinder cones are made of _____

pyroclastic deposits

what are composite volcanoes made of?

pyroclastic deposits

The principle mineral used in making glass is

quartz

a hot spot that occurs in oceanic crust is likely to produce which of the following types of eruptions

quiet and effusive

Hardness describes a mineral's _______

resistance to being scratched

which of the following types of magma has the highest viscosity?

rhyolitic

what type of volcanoes are the highest

shield volcanoes