Historical
Geology R.
Lopez
The Rock Cycle and Igneous
Rocks
1)
Read
the discussion on igneous rocks on pages 40-42.
2)
Be
able to sketch and discuss the rock cycle diagram.
3)
What
is the origin of the term “igneous”, and what do all igneous rocks have in
common?
4)
What
are sediments, what are they composed of, and where are they deposited?
5)
What
is the difference between sediments and sedimentary rock?
6)
What
does the process of lithification involve?
7)
What
is the most distinctive feature of sedimentary rocks as a group?
8)
What
is the origin of the term “metamorphic”, and how do metamorphic rocks form?
9)
Igneous
rocks are classified based principally on what two characteristics?
10)
Why
is grain size important? Contrast grain
sizes of volcanic and plutonic rocks.
11)
Draw
a simple cross-section showing a magma chamber, pluton, sill, dike, and country
rock. How do sills and dikes
differ? How do intrusive and extrusive
igneous rocks differ? (see Fig. 2-11 page 41)
12)
What
is pyroclastic? What is fall-out
tuff? What is ash-flow tuff?
13)
What
is a batholith? Name one batholith in
California.
14)
Describe
a porphyritic texture, and what does it tell you about the cooling history of
the rock?
15)
Name
the principal igneous rock-forming silicate minerals, and group them as “light”
(felsic) or “dark” (mafic) minerals.
16)
Know
the directions that SiO2, FeO, dark minerals, and light minerals increase or
decrease according to rock type on the chart.
17)
Peridotite
is important for at least two reasons.
What are they?
18)
What
is the most abundant type of volcanic rock on earth? Be able to make a simple cross-section sketch of oceanic crust at
a mid-ocean ridge and show where basalt and gabbro are found.
19)
What
are pillow basalts and what is their significance? (See text, Fig 6.14 p. 143, Fig 9.1b p. 214, and Fig 8.7c p.
196).
20)
Be
able to sketch the plate tectonic setting of the common rock types (granite,
rhyolite, granodiorite, andesite, diorite, basalt, and gabbro) and say a few
words about their origin.