IGNEOUS PROCESSES

Question 1

Which of the following is considered a warning sign of imminent eruption?

Answer 1

earthquake activity

Question 2

Obsidian is classified as having a __________ texture.

Answer 2

glassy

Question 3

Which type of volcano erupts with the most force?

Answer 3

composite

Question 4

Which of the following describes an elongated crack that may serve as a conduit for lava to erupt on the surface?

Answer 4

Fissure

Question 5

Earthquakes can tell us a lot about the possibility of an eruption. If there are too few earthquakes ________.

Answer 5

it may mean the magma has stopped moving implying it is about to give way.

Question 6

Most hotspots are ________.

Answer 6

basaltic

Question 7

Magma may cool and crystallize to become solid igneous rock

Answer 7

very slowly (in centuries to a million years) when it forms a deep pluton.

Question 8

Why does magma tend to rise upward once it forms?

Answer 8

The magma is less dense than the surrounding rock.

Question 9

A moving, glowing, descending cloud of hot gases and volcanic pieces

Answer 9

is called a pyroclastic flow or nuée ardente.

Question 10

Which of the following is not a characteristic of pyroclastic flow?

Answer 10

They move very slow and are not dangerous.

Question 11

Which describes the melting that takes place when deep hot rock rises to shallower depths without cooling?

Answer 11

Decompression melting

Question 12

Which type of volcano is the largest but not necessarily the most eruptive?

Answer 12

shield

Question 13

Which eruption or volcano type is likely to produce the most violently ejected pyroclastic fragments?

Answer 13

Stratovolcano

Question 14

Pyroclastic flow can be composed of all but which of the following?

Answer 14

water

Question 15

A sill runs ________ to the surrounding rock.

Answer 15

parallel

Question 16

The image below (immediately to the right of the person’s head) is an example of a small __________.

Answer 16

dike

Question 17

The difference between magma and lava is that __________.

Answer 17

magma is found beneath the surface, whereas lava is found at the surface

Question 18

Granite, a course-grained, felsic intrusive igneous rock is most similar in mineral composition to __________, which is a fine-grained, felsic extrusive equivalent.

Answer 18

rhyolite

Question 19

In the figure provided below, what type of igneous intrusion is the horizontal rock unit indicated by the arrow?

Answer 19

sill

Question 20

Which of the following is not a way in which geologists can monitor a volcano with the goal of making short-term predictions about volcanic activity?

Answer 20

radioisotope dating

Question 21

Which of the following is not considered a type of pyroclastic debris?

Answer 21

pahoehoe

Question 22

Magma tends to __________.

Answer 22

move upward, away from where it formed

Question 23

Which type of magma has the greatest silica content?

Answer 23

felsic

Question 24

Bubbles trapped in lava after the molten material are cooled are called __________.

Answer 24

vesicles

Question 25

Ash, and larger fragments of pumice are all examples of __________.

Answer 25

pyroclastic debris

Question 26

An irregular-shaped and bloblike igneous rock body that cooled beneath the surface of Earth is a __________.

Answer 26

pluton

Question 27

Columnar jointing forms primarily because of __________

Answer 27

Contraction and cracking of rock during the cooling process

Question 28

Compared with coarse-grained igneous rocks, fine-grained igneous rocks __________.

Answer 28

cool and solidify more quickly

Question 29

Decompression melting occurs at both __________ and __________.

Answer 29

mid-ocean ridges; hotspots

Question 30

All things equal, a magma will have __________ viscosity than a lava.

Answer 30

lower

Question 31

__________ form from piles of pyroclastic debris (mainly lapilli) that fountain out of a vent during an effusive eruption.

Answer 31

Cinder cones

Question 32

Despite the fact that the temperatures within Earth are hot enough to melt rock, Earth is mostly solid. Why do the rocks within Earth NOT melt?

Answer 32

The pressure is too high.

Question 33

A batholith is a(n) __________.

Answer 33

large compound igneous intrusion

Question 34

The interior of Earth consists almost entirely of __________ rock.

Answer 34

solid

Question 35

Viscosity controls how __________.

Answer 35

fast a fluid flows