Geology 101: Introduction to Geology
Exam #1


The drawing below shows a view of the Earth cut open to reveal all the major layers. Use it to answer questions 1 through 3.

1. Which arrow points to the crust?
a. A
b. B
c. C
d. D
e. E

2. Volcanic rocks are created when magmas reach the surface. Which arrow points to the part of the Earth where most of those magmas come from?
a. A
b. B
c. C
d. D
e. E

3. Which arrow points to the part of the Earth that is almost entirely molten?
a. A
b. B
c. C
d. D
e. E

4. Which type of bonding is most important in minerals?
a. covalent
b. metallic
c. van der Waals
d. hydrogen
e. ionic

5. Metallic, non-metallic, pearly, silky, resinous and earthy are all terms used to describe a minerals
a. hardness
b. cleavage
c. crystallinity
d. luster
e. streak

6. Why are silicates the most abundant group of minerals in the Earths crust?
a. because silicon and oxygen are the two most abundant rocks in the Earths crust
b. because they are not stable at high pressure
c. because silicon and oxygen are the two most abundant minerals in the Earths crust
d. because silicon and oxygen are the two most abundant elements in the earths crust
e. because they are not stable at low pressure

7. All ferromagnesian minerals
a. are silicates
b. contain little silica
c. contain significant amounts of Fe and Mg
d. are found in the Earths core
e. all of the above

8. There have been many estimates of the age of the Earth. Often the estimates depend on how you think the Earth evolved. How old did the catastrophists think the Earth was?
a. about 2 years
b. about 340 years
c. about 4000 years
d. about 16 million years
e. about 4.6 billion years

9. How old is the Earth?
a. about 2 years
b. about 340 years
c. about 4000 years
d. about 16 million years
e. about 4.6 billion years

10. The Andes Mountains are associated with a _________________.
a. mid ocean ridge
b. subduction zone
c. transform fault
d. hot spot
e. continental rift

11. Ruby and sapphire are gems. They both are the same mineral, and that mineral is ____________.
a. diamond
b. emerald
c. beryl
d. corundum
e. quartz

12. Which of the following is a carbonate mineral?
a. quartz, SiO₂
b. corundum, Al₂O₃
c. tremolite, Ca₂Mg₅Si₈O₂₂(OH)₂
d. calcite, CaCO₃
e. all of the above

13. The type of bonding in which atoms give up electrons to become cations, or gain electrons to become anions, is called _____________ bonding.
a. covalent
b. metallic
c. van der Waals
d. hydrogen
e. ionic

14. What is the most common member of the amphibole group of minerals?
a. quartz
b. biotite
c. calcite
d. hornblende
e. corundum

15. Which common mineral can generally be identified because it fizzes when a drop of hydrochloric acid is put on it?
a. quartz
b. biotite
c. calcite
d. hornblende
e. corundum

16. Granite is a coarse grained igneous rock containing lots of quartz and K-feldspar. What is the name of a fine grained rock that contains the same minerals?
a. granite
b. basalt
c. andesite
d. tuff
e. rhyolite

17. Which of the following is a type of pyroclastic rock?
a. granite
b. basalt
c. andesite
d. tuff
e. rhyolite
                                      
18. Bowens Reaction Series describes
a. the temperatures at which various minerals melt
b. the temperatures at which various minerals crystallize from a magma
c. general chemical relationships between various igneous minerals
d. one way a magma may become differentiated
e. all of the above

19. Why are crystals in pegmatites so large?
a. Because they form at high temperature
b. Because the form over long periods of time
c. Because they form from silica rich magmas
d. Because the magmas they form from are very rich in fluids
e. Because they are low pressure rocks

20. When magma reaches the surface, we call it
a. glass
b. volatile
c. basalt
d. lava
e. pegmatite

21. How does the composition of melt produced by partial melting compare with the composition of the parent rock?
a. it will be more basaltic
b. it will be denser
c. it will be more mafic
d. it will be richer in silicon and alkali elements (more silicic)
e. all of the above

22. The largest of all intrusive igneous bodies is called a ___________________.
a. volcano
b. stock
c. dike
d. batholith
e. sill

23. ______________ is vesicular ejecta that is the product of basaltic magma.
a. bombs
b. obsidian
c. pumice
d. scoria
e. lahar

24. __________________ is a light colored vesicular rock commonly having the composition of granite.
a. bombs
b. obsidian
c. pumice
d. scoria
e. lahar

25. Which of the following is an example of hot spot volcanism?
a. Cascade Mountains
b. Appalachian Mountains
c. Hawaiian Islands
d. Andes Mountains
e. all of the above

26. Which magmas are most likely to result in violent eruptions?
a. those that are very viscous
b. those that are rich in silicon
c. those that are rich in H₂O, CO₂ and other gases
d. those that have a granitic composition
e. all of the above are correct

27. What type of volcano is most often associated with extensive pyroclastic deposits?
a. shield volcano
b. cinder cone
c. batholith
d. stratovolcano
e. caldera

28. In 1902, the town of St. Pierre, Martinique, was destroyed by a
a. lahar
b. shield volcano
c. mudslide
d. pyroclastic flow
e. NDSU geology class

29. According to Dexy, the #1 reason why we see magmas of different compositions at the earths surface has to do with
a. the source region the magma comes from
b. the effects of gravity
c. the pressure behind the magma
d. how much melting occurred to create the magma
e. whether the magma contained CO₂ or H₂O

30. Which of the following is a type of mafic plutonic rock?
a. basalt
b. andesite
c. rhyolite
d. gabbro
e. granite

31. Which of the following are island arcs?
a. Japan
b. Aleutian Islands
c. Tongas Islands
d. Marianas Islands
e. all of the above

32. Most geologists would consider ice a mineral, but not water. Why?
a. water is crystalline
b. water is not crystalline
c. ice is not a solid
d. ice is inorganic
e. water is inorganic

33. An elements atomic number is
a. the number of neutrons in its nucleus
b. the number of electrons in its nucleus
c. the number of neurons in its nucleus
d. the number of protons in its nucleus
e. any of the above because they are all the same

34. Of the common elements found in the Earths crust, which is the only one that easily becomes an anion?
a. carbon
b. chlorine
c. aluminum
d. oxygen
e. iron

35. Enstatite is a mineral with formula MgSiO₃. It is ionically bonded. Si has a charge of +4, and oxygen has a charge of -2. What is the charge of the Mg ion?
a. +1
b. +2
c. +3
d. -1
e. -2

36. Which of the following is a mafic mineral?
a. quartz
b. muscovite
c. K-feldspar
d. olivine
e. all of the above

37. Diamonds are thought of as being very valuable, but actually on a weight basis, the most valuable gems are _____________.
a. opals
b. pearls
c. rubies
d. emeralds
e. sapphire

38. If you were to take a journey to the center of the earth, you would find that:
a. both pressure and temperature increase as you go down
b. both pressure and temperature decrease as you do down
c. pressure increases but temperature decreases as you go down
d. temperature increases but pressure decreases as you go down
e. all of the above

39. Which is true?
a. rocks are made of minerals, and minerals are compounds made of elements
b. rocks are made of compounds, and compounds minerals are minerals made of elements
c. rocks are made of elements, and elements are the same thing as minerals made of compounds
d. rocks are made of minerals, and minerals are elements made of compounds
e. rocks are made of elements, and elements are made of silicon and oxygen

40. The boundary between the crust and the mantle is the
a. P wave shadow zone
b. inner core
c. outer core
d. Benioff zone
e. Moho

41. Geologists and physicists believe the core of the Earth is mostly
a. quartz
b. nickel
c. carbon
d. magnesium
e. iron

42. Why do magmas rise to the surface?
a. Coriolis force
b. they are aphanitic
c. magma is not as dense as solid rock
d. magma is denser than solid rock
e. as ash settles it pushes down on a caldera

43. A porphyritic rock is one
a. in which mineral grains are generally small
b. in which mineral grains are generally large
c. that contains large phenocrysts in a matrix
d. that forms from settled ash
e. that contains abundant glass such as obsidian

44. Which of these is/are associated with a subduction zone?
a. Columbia River flood basalts
b. Mt. Rushmore
c. Sierra Nevada batholith
d. Hawaiian islands
e. volcanic island arcs

45. In general, gems are
a. rare minerals
b. radioactive minerals
c. beautiful varieties of common minerals
d. not colored or dyed or altered in any way from the way they occur naturally
e. made of diamond

46. Maurice and Katya Kraft
a. were killed by a volcano
b. invented the reflecting goniometer
c. are the names of the (hypothetical) first minerals every discovered
d. were the first people to figure out that continents drift
e. are responsible for coming up with the system for dividing minerals into classes

47. What is the prime characteristic that mineralogists use to put minerals into classes?
a. hardness
b. how the minerals formed
c. color
d. size of mineral grains
e. chemistry

48. Two minerals that have identical composition but different atomic arrangements are called _________.
a. halides
b. silicates
c. kimberlites
d. facets
e. polymorphs

49. All silicate mineral have what in common?
a. they all form from magmas
b. they all contain silicon-oxygen tetrahedra
c. they all contain iron and magnesium
d. they all contain silicic acid
e. they all break down quickly at the Earths surface

50. The reason over 50 people died when Mt. St. Helens erupted is because
a. the eruption took place on Monday
b. the eruption was a fissure eruption
c. the eruption was a complete surprise
d. the basalt flowed over the ground at high speed
e. people didnt believe the warnings and were too close