Download Rocks Winter 2016

READING QUESTIONS: Rocks
PSCI 131
Winter 2016
NAME________________________
DUE: Monday, April 25th
74 pts
Igneous Rocks: “Formed by Fire” (p. 34-43)
1. What is magma? __________________________________________________________________
2. Extrusive igneous rocks form at the Earth’s ________________, and intrusive igneous rocks form deep
____________________. (2 pts)
3. Fill in the blanks (p. 34): “The rate of cooling strongly influences _______________. If magma cools
very _____________, ions can migrate over great distances. Consequently, _________ cooling results
in the formation of fewer, _________________ crystals. On the other hand, if cooling occurs
________________, the ions lose their motion and quickly combine. This results in a large number of
________ crystals all competing for the available ions. Therefore, rapid cooling results in the formation
of a solid mass of _____________ intergrown crystals. (7 pts)
4. To what mineral group do almost all minerals found in igneous rocks belong? ____________________
5. Fill in the blanks (p. 38): “If molten rock containing some ____________ crystals moves to a different
_________________________ - for example, by erupting at the surface – the remaining ___________
portion of the lava cools more __________________. The resulting rock, which has _____________
crystals embedded in a matrix of ___________________ crystals, is said to have a
______________________ texture.” (7 pts)
6. List the four igneous compositional groups in order of decreasing silica content, and in order of
increasingly darker color. (4 pts)
Most silica
a. ______________________________
Lightest color
a. _______________________________
b. ______________________________
b. ______________________________
c. ______________________________
c. ______________________________
d. ______________________________
d. ______________________________
Least silica
Darkest color
7. Match each of the following igneous textural terms to the correct definition: (3 pts)
a. Coarse-grained
Composed of unordered atoms
_____
b. Fine-grained
Crystals large enough to be seen without a microscope
_____
c. Vesicular
Contains voids left by escaping magma gases
_____
d. Glassy
Composed of two distinctly different crystal sizes
_____
e. Porphyritic
Fragmental; composed of ash and larger rock fragments
_____
f. Pyroclastic
Crystals too small to see without a microscope
_____
8. Fill in this igneous classification chart with the correct rock names. Refer to Figure 7 on page 39. (4 pts)
Granitic
Andesitic
Basaltic
Ultramafic
Coarse-grained
Fine-grained
9. According to Bowen’s Reaction Series (p. 42), which of the following is the correct order of mineral
crystallization from a cooling magma?
a. Pyroxene, then amphibole, then olivine, then biotite
b. Olivine, then pyroxene, then amphibole, then biotite
c. Olivine, then amphibole, then biotite, then pyroxene
d. Biotite, then amphibole, then pyroxene, then olivine
10. Fill in the blanks (p. 42-43): “Crystal settling… occurs when the earlier formed minerals [in a magma]
are more ___________ (heavier) than the liquid portion and ________ towards the bottom of the magma
chamber… When the remaining molten material solidifies… it will form a rock with a
________________________________ much ________________ from the parent magma. (4 pts)
Sedimentary Rocks: Compacted and Cemented Sediment (p. 43-49)
11. About _____% of rock exposed at Earth’s surface is sedimentary rock.
12. What two minerals are most abundant in detrital sedimentary rocks? ____________________________
(2 pts)
13. Match each detrital sedimentary rock to its description. (3 pts)
a. Conglomerate
Sandstone with abundant feldspar grains
______
b. Breccia
Very fine-grained sediment
______
c. Sandstone
Medium-grained sediment, little or no feldspar grains
______
d. Arkose
Fine-grained sediment
______
e. Siltstone
Coarse-grained, angular sediment
______
f. Shale
Coarse-grained, rounded sediment
______
14. For each sedimentary rock listed, indicate whether it is biochemical or chemical. (3 pts)
a. Coquina
_______________________
b. Chalk
_______________________
c. Rock salt
_______________________
d. Crystalline limestone
_______________________
e. Travertine
_______________________
f. Fossiliferous limestone
_______________________
15. Fill in the blanks (p. 47-48): “____________________ refers to the processes by which sediments are
transformed into solid sedimentary rocks. One of the most common processes is
_______________________. As sediments accumulate through time, the weight of the overlying
sediments __________________ the deeper sediments. As the grains are pressed closer and closer,
_______________________ is greatly reduced…Compaction is most effective in converting very
____________________________ into sedimentary rocks.” (5 pts)
16. Fill in the blanks (p. 48): “Because sand and coarse sediments are not easily compressed, they are
generally transformed into sedimentary rock by the process of ______________________. The
cementing materials are carried in a ____________________________ that percolates through the pore
spaces between particles. Over time, the cement _________________________ onto the sediment
grains, fills in the open spaces, and acts like a ___________ to join the particles together.” (4 pts)
17. Give an example of one rock type that is lithified by compaction, and one that is lithified by cementation.
(2 pts)
a. Compaction: ____________________________
b. Cementation: ___________________________
Metamorphic Rocks: New Rock from Old (p. 50-54)
18. Fill in the blanks (p. 50): “Metamorphism…is a process that leads to changes in the
_____________________, _________________ (for example, grain size), and sometimes |
____________________________________ of rocks…Most metamorphic changes occur at the
elevated ____________________ and ____________________ that exist in the zone beginning
________________________ below Earth’s surface and extending into the _______________.” (7 pts)
19. During metamorphism, rocks usually get hot enough to melt completely. TRUE or FALSE
20. How does contact metamorphism take place? (2 pts) _________________________________________
____________________________________________________________________________________
____________________________________________________________________________________
21. List the four agents of metamorphism. (2 pts)
a. _________________________________
b. _________________________________
c. _________________________________
d. _________________________________
22. Which agent is the most important, and why? (3 pts) ________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
23. What is the difference between differential stress and confining pressure? (2 pts)
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
__________________________________________________________________________________
24. Fill in the blanks (p. 53): “Foliation refers to any nearly ___________ arrangement of mineral grains or
structural features within a rock…In metamorphic environments, foliation is ultimately driven by
________________________________ that _________________ rock units, causing mineral grains in
preexisting rocks to develop __________________ alignments.” (4 pts)
25. EXTRA CREDIT: Label each photo below with the type of foliation shown (rock cleavage,
compositional banding, or alignment of flat minerals – each will be used once). (3 pts)
_____________________________
_____________________________
_____________________________