The Solid Earth - Chapter 7: Intrusive Igneous Activities

Question 1

Intrusive igneous bodies form when ___ crystallizes within the earth’s crust

Answer 1

magma

Question 2

Name two ways that intrusive igneous rocks are classified according to shape

Answer 2

tabular (sheetlike)

massive

Question 3

Name two ways that intrusive igneous bodies are classified based on orientation to host rock

Answer 3

discordant (cutting across sedimentary beds)

concordant (parallel to sedimentary beds)

Question 4

Discordant sheetlike bodies produced when magma is injected into fractures that cut across rock layers

Answer 4

Dikes

Question 5

Dikes are typically (more/less) vulnerable to weathering than surrounding rock

Answer 5

less

Question 6

Tabular bodies formed when magma is injected along sedimentary bedding surfaces

Answer 6

Sills

Question 7

Horizontal sills are thought to form from ___ lava

Answer 7

fluid

Question 8

Which type of sill is the most common - vertical or horizontal?

Answer 8

Horizontal

Question 9

Sills are most often composed of ____ magma which is typically quite fluid

Answer 9

Basaltic

Question 10

Sills form only at rather ___ depths where the pressure exerted by the weight of overlying strata is relatively low

Answer 10

shallow

Question 11

The cracks that form as a consequence of contraction that occurs during the cooling of molten rock

Answer 11

columnar joints

Question 12

These are similar to sills because they form when magma is intruded between sedimentary layers in a near surface environment

Answer 12

Laccoliths

Question 13

By far these are the largest intrusive igneous bodies

Answer 13

Batholiths

Question 14

The magma that forms laccoliths is more ___

Answer 14

viscous

Question 15

Smaller intrusive bodies that behave like batholiths

Answer 15

stocks

Question 16

Batholiths are usually composed of rock types having chemical compositions near the ___ end of the spectrum

Answer 16

granite

Question 17

True or false: batholiths frequently compose the cores of mountain systems. Here uplift and erosion have removed the surrounding rock to expose the resistant igneous body

Answer 17

True