Earth Science, Tarbuck Chap 6

Question 1

Mafic magmas have

Answer 1

Lower Silica Content, Lower Gas content, Erupt at higher temperatures

Question 2

Felsic Magmas have

Answer 2

Higher Silica Content, Higher Gas Content, Erupt at Lower temperatures

Question 3

Magmas generated by melting of mantle rocks tend to have what composition

Answer 3

Mafic Composition

Question 4

Largest quantity of basaltic magmas is erupted where

Answer 4

Mid-Ocean Ridges and Hot-Spot Volcanism

Question 5

What happens in Continental Crust that changes magma generated by partial melting to have a more intermediate composition

Answer 5

the magma usually is denser than overlying continental crust, resulting in the magma pooling at the crust-mantle boundary. This causes overlying crust to be melted and forming a more silica rich mix as the magma then continues to rise.

Question 6

The two primary factors that determine how magma erupts are its

Answer 6

Viscosity and Gas content

Question 7

What are Effusive Eruptions

Answer 7

Eruptions that are quiet/non-violent

Question 8

What does viscosity measure

Answer 8

a fluid’s mobility

Question 9

magma’s viscosity depends primarily on its

Answer 9

Temperature and Silica Content

Question 10

The more silica in a magma,

Answer 10

The more viscous it will be

Question 11

The hotter the magma,

Answer 11

the more fluid it will be

Question 12

The most abundant gasses in a magma is

Answer 12

Water vapor and carbon dioxide

Question 13

Most Felsic Magma tend to extrude ____ instead of lava

Answer 13

Volcanic Ash

Question 14

Fluid basaltic magma tend to generate 2 types of lavas, called ____ and ____

Answer 14

aa and Pahoehoe

Question 15

Describe aa flows

Answer 15

surfaces of rough jagged blocks
with dangerously sharp edge

Question 16

Describe Pahoehoe Flows

Answer 16

smooth surfaces that sometimes resemble twisted braids of ropes

Question 17

Difference between aa and pahoehoe flows

Answer 17

pahoehoe lavas are hotter and more fluid than aa flows

Question 18

What is a lava tube

Answer 18

Cave-like tunnels developed by Pahoehoe flows

Question 19

Describe pillow lavas

Answer 19

Tube-like Structures formed at mid-ocean ridges caused by excessive cooling and break through of magma

Question 20

Dissolved gasses in magma is called

Answer 20

Volatiles

Question 21

what are pyroclastic materials

Answer 21

rock and fragments of lava and glass

Question 22

What are pyroclastic materials also called

Answer 22

Tephra

Question 23

What is Lapilli

Answer 23

Tephra between 2-64 mm

Question 24

What is volcanic Ash

Answer 24

Tephra smaller than 2 mm

Question 25

2 tephra types larger than 64 mm

Answer 25

Volcanic Bombs and Volcanic Blocks

Question 26

What is a cinder cone

Answer 26

small, steep-sided volcanic landform made primarily of pyroclastic material,

Question 27

What is a fissure on a volcano

Answer 27

Crack developed by Magma forcing its way up to the surface

Question 28

what is a conduit on a volcano

Answer 28

Pipe-shaped channel/pipe that carries magma up through a fissure

Question 29

What is a vent on a volcano

Answer 29

surface opening of the volcano

Question 30

What are Calderas on a volcano

Answer 30

a large depression formed when a volcano erupts and collapses

Question 31

What is crater on volcano

Answer 31

bowl-shaped depression or hollow formed at the summit of the volcano created by explosions caused by volcanic activity

Question 32

Describe Parasitic Cones

Answer 32

flows formed by fissures that develop along the flanks (sides) or at the base of the volcano

Question 33

What are Fumaroles

Answer 33

Vents on the side of a volcano that only emit gas

Question 34

Describe Shield Volcanoes

Answer 34

accumulation of fluid basaltic lavas and exhibit the shape of a broad, slightly domed structure that resembles a warrior’s shield

Question 35

What are seamounts

Answer 35

Underwater volcanoes

Question 36

Most Shield Volcanoes begin on the Ocean Floor as ______

Answer 36

Seamounts

Question 37

Largest Shield Volcano

Answer 37

Mauna Loa

Question 38

What is a composite volcano also called

Answer 38

Stratovolcano

Question 39

What are Composite Volcanoes

Answer 39

volcanoes with intermediate-felsic composition

Question 40

Composite Volcanoes are made from what type of magma

Answer 40

Silica-Rich magma

Question 41

Intermediate Magma generates _____ volcanoes that eject lots of _________

Answer 41

Composite, Pyroclastic

Question 42

Composite Volcanoes often have ___ slopes

Answer 42

Steep

Question 43

Shield Volcanoes often have ____ slopes

Answer 43

Gentle

Question 44

Pyroclastic Flows are Also known as

Answer 44

Nuee Ardentes

Question 45

What is a pyroclastic flow

Answer 45

a dense, destructive mass of very hot ash, lava fragments, and gases ejected explosively from a volcano and typically flowing downslope at great speed

Question 46

Describe Lahars

Answer 46

Fluid Mudflow caused when volcanic debris becomes saturated with water and rapidly moves down volcanic slopes forming mostly around volcanoes with snow-laden peaks

Question 47

How can Volcanic Eruptions cause Tsunamis

Answer 47

Collapse of the Volcanic cone can fall into the water, causing a large wave

Question 48

How do volcanic eruptions affect the atmosphere

Answer 48

volcanoes eject dust-sized particles of volcanic ash and sulfur dioxide gas high into the atmosphere. The ash particles reflect sunlight back to space, producing temporary atmospheric cooling

Question 49

What are Volcanic Necks

Answer 49

roughly cylindrical forms of igneous rock when the magma in volcanic conduit cools after a volcano goes inactive. These can be seen when volcanoes are weathered down.

Question 50

What are Flood Basalts

Answer 50

Formed when Fissure Eruptions blanket wide areas in basalt.

Question 51

What are fissure eruptions

Answer 51

when lava eruptions are formed from ridges, or dikes, without a single conduit of lava.

Question 52

Intrusive Bodies of Magma are also called

Answer 52

Plutons

Question 53

An intrusion is said to be Discordant if

Answer 53

They cut across existing structures

Question 54

An intrusion is said to be Concordant if

Answer 54

they inject parallel to features such as sedimentary strata

Question 55

What is a Dike

Answer 55

discordant bodies that form when magma is forcibly injected into fractures and cut across bedding surfaces and other structures in the host rock

Question 56

What is a Sill

Answer 56

nearly horizontal, concordant bodies that form when magma exploits weaknesses between sedimentary beds or other rock structures

Question 57

What are dikes mostly do

Answer 57

serve as tabular conduits that transport magma upward

Question 58

What are sills mostly do

Answer 58

accumulate magma and increase in thickness

Question 59

Where do Dikes and Sills usually form

Answer 59

They form close to the surface, where the crust is brittle enough to fracture

Question 60

Largest intrusive bodies are

Answer 60

Batholiths

Question 61

Describe a batholith

Answer 61

mammoth linear structures several hundred kilometers long and more than 100 kilometers wide

Question 62

What is the Difference between Batholiths and Stocks

Answer 62

surface exposure less than 100 square kilometers

Question 63

What is a Laccolith

Answer 63

igneous rock forcibly injected between sedimentary strata, so as to arch the beds above while leaving those below relatively flat, kind of like a mushroom top.