Geology Reference
In-Depth Information
Important Terms
aphanitic texture (p. 93)
assimilation (p. 92)
batholith (p. 99)
Bowen's reaction series (p. 89)
concordant pluton (p. 98)
country rock (p. 92)
crystal settling (p. 91)
dike (p. 98)
discordant pluton (p. 98)
felsic magma (p. 87)
hot spot (p. 91)
igneous rock (p. 87)
intermediate magma (p. 87)
laccolith (p. 98)
lava (p. 86)
lava fl ow (p. 87)
mafi c magma (p. 87)
magma (p. 86)
magma chamber (p. 89)
magma mixing (p. 92)
mantle plume (p. 91)
phaneritic texture (p. 93)
pluton (p. 97)
plutonic (intrusive igneous) rock
(p. 87)
porphyritic texture (p. 93)
pyroclastic (fragmental) texture
(p. 94)
pyroclastic materials (p. 87)
sill (p. 98)
stock (p. 99)
stoping (p. 99)
vesicle (p. 94)
viscosity (p. 88)
volcanic neck (p. 99)
volcanic pipe (p. 99)
volcanic (extrusive igneous) rock
(p. 87)
Review Questions
1. An igneous rock such as granite with minerals large
enough to see without magnifi cation has a __________
texture.
a. ____ assimilated;
b. ____ phaneritic;
c. ____ volcanic;
d. ____ pyroclastic;
e. ____ clastic.
2. Which one of the following is a tabular discordant
pluton?
a. ____ batholith;
b. ____ laccolith;
c. ____ sill;
d. ____ dike;
e. ____ stock.
3. Magma characterized as intermediate
a. ____ fl ows more readily than mafi c magma;
b. ____ has between 53% and 65% silica;
c. ____ crystallizes to form rhyolite;
d. ____ is one from which ultramafi c rocks
crystallize;
e. ____ makes up most of the mantle.
4. Which pair of the following igneous rocks has the same
composition?
a. ____ diorite-andesite;
b. ____ peridotite-pegmatite;
c. ____ gabbro-rhyolite;
d. ____ basalt-granite;
e. ____ obsidian-scoria.
5. One process that brings about chemical changes in
magma is
a. ____ magma mixing;
b. ____ crystal inversion;
c. ____ discordant separation;
d. ____ mafi c differentiation;
e. ____ ultramafi c accumulation.
6. Islands such as the Hawaiian chain form at hot spots
that overlie a
a. ____ volcanic neck;
b. ____ convergent plate boundary;
c. ____ divergent plate boundary;
d. ____ granite batholith;
e. ____ mantle plume.
7. Which one the following statements about batholiths is
correct?
a. ____ They are mostly concordant;
b. ____ They are made up of basalt and gabbro;
c. ____ They form mostly at convergent plate
boundaries;
d. ____ They formed from a single huge mass of magma;
e. ____ They have a mushroom-like geometry and are
concordant.
8. The igneous rock tuff is composed of
a. ____ pyroclastic materials;
b. ____ calcium-rich plagioclase and pyroxene;
c. ____ obsidian and pumice;
d. ____ granite and vesicles;
e. ____ phenocrysts.
9. The phenomenon by which pieces of country rock are
detached and engulfed by rising magma is
a. ____ assimilation;
b. ____ crystal settling;
c. ____ stoping;
d. ____ Bowen's reaction series;
e. ____ viscosity.
10. A fl uid's resistance to fl ow is called its
a. ____ plutonic inertia;
b. ____ composition;
c. ____ texture;
d. ____ melting point;
e. ____ viscosity.
11. What factors control the viscosity of magma and lava?
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