Geology Exam 3

TRUE/FALSE QUESTIONS (A=TRUE, B=FALSE)

2. Rocks are defined as naturally-formed aggregates of minerals or mineral-like TRUE

1. The atomic number of an element is equal to the number of protons in each atom. TRUE

substances.

3. A mineral specimen with a Mohs’ hardness of 5 can scratch a mineral specimen TRUE

with a hardness of 8.

4. The only way of identifying a mineral is by its color. FALSE

5. The sequence in which minerals crystallize in a cooling igneous melt is called TRUE

Bowen’s Reaction Series.

6. Extrusive (ie. volcanic) igneous rocks are typically fine grained because they FALSE

crystallized slowly, deep below the Earth’s surface.

7. Most convergent plate boundaries coincide with the crests of submarine mountain FALSE

ranges called mid-oceanic ridges.

8. Most of the world’s earthquakes and volcanoes are located along plate TRUE

boundaries.

9. A “tectonic” plate is the thin outer rigid shell of the Earth that overlies a more TRUE

ductile layer in the upper Mantle.

10. Passive margins are found on the edges of most of the landmasses bordering the FALSE

Pacific Ocean.

11. The sea floor is older than the Earth. TRUE

12. The magma that is created within a subduction zone forms either island arcs or

belts of igneous activity, called continental arcs, on the edges of continents.

13. Mt. Fuji in Japan and Mt. St. Helens in Washington State are examples of shield

volcanoes.

14. Olympus Mons, possibly the largest volcano in the Universe, is found on Mars.

15. Basaltic magmas crystallize at higher temperatures than granitic magmas. TRUE

16. Pillow structures, pillow-shaped rounded masses, form where lava is cooled under TRUE

water

17. A dike is an igneous intrusion that is emplaced PARALLEL to the layers of country

rock in which it intrudes. FALSE

MULTIPLE CHOICE

18. Hot, liquid rock beneath the surface of the Earth is termed ____________.

A. lava

B. magma

C. volatiles

D. brimstone

19. In order for a particular type of material to be classified as a mineral, it must ___.

A. be a solid

B. occur naturally

C. have a crystalline structure

D. have a definite chemical composition

E. All of the answers are correct.

20. The two most abundant elements in Earth’s crust are __.

A. oxygen and silicon

B. carbon and hydrogen

C. carbon and oxygen

D. hydrogen and oxygen

E. iron and magnesium

21. _____ are igneous rocks that are silica-deficient but high in iron and magnesium.

A. mafic

B. intermediate

C. felsic

D. granite

E. oxide

22. ______ are extremely coarse-grained with crystal up to 10 meters across.

A. Granites

B. Ultramafic

C. Basalts

D. Pegmatites

E. Marbles

23. Fractional crystallization is the process of:

A. Splitting a mineral in half.

B. Crystallizing different minerals from a magma at different temperatures.

C. Crystallizing all minerals within a magma at the same time.

D. Combining mafic and felsic magma together.

24. Evidence in support of continental drift includes _____.

A. glacial striation patterns

B. fossil distribution on different continents

C. fit of continental margins

D. matching of geologic patterns on continents

E. all of the choices are correct

25. One possible mechanism to drive (enable) plate tectonics is _____.

A. meteor impacts

B. earthquake energy

C. mantle convection

D. gravity sliding

E. Benioff drive

26. Sea-floor spreading implies that sea-floor rocks should be _______________.

A. the same age throughout

B. youngest on the crest of mid-ocean ridges

C. younger as water becomes colder

D. younger toward the trench

E. youngest on the continental shelf

27. The San Andreas Fault is an example of an example of a(n)

A. convergent plate boundary

B. divergent plate boundary

C. transform plate boundary

D. subduction zone

E. oceanic lithosphere

28. Plate tectonics is a unifying idea that helps explain where and why there are ___

on Earth.

A. earthquakes

B. volcanoes

C. mountain belts

D. oceanic ridges and trenches

E. All of the answers are correct.

29. Plates are known to be moving away from each other ___.

A. across mountain ranges like the Himalayan Mountains

B. across subduction zones

C. across mid-ocean ridges

D. across the stable interior of continents

E. along transform faults

30. The formation of magma within Earth is NOT caused by which of the following

processes?

A. decompression (drop in pressure)

B. loss of heat to the atmosphere at volcanoes

C. addition of volatiles (such as water)

D. transfer of heat from adjacent magma or very hot rocks

31. As compared to coarse-grained igneous rocks, all fine-grained igneous rocks

____________.

A. cool and solidify more quickly

B. cool and solidify more slowly

C. solidify at higher temperatures

D. solidify at lower temperatures

32. The lava shown in the image on the right, with a smooth, ropey texture, is called:

A. Pahoehoe

B. Aa

C. Haleakela

D. Poy

E. Pele’s hair

33. Most commonly, felsic igneous rocks ____________.

A. contain more iron and magnesium than intermediate rocks

B. are lighter in color than mafic rocks

C. are darker in color than mafic rocks

D. are found in oceanic crust

34. A ___ is a hot, turbulent mixture of expanding gases and volcanic ash that flows

rapidly down the side of a volcano.

A. pyroclastic cloud

B. mud flow

C. lava flow

D. pyroclastic flow

E. hyaloclastic flow

35. Explosive or voluminous eruptions may cause the volcano to collapse on the floor of

the (now empty) magma chamber, producing a broad depression termed a _______.

A. crater

B. lahar

C. caldera

D. fissure

36. Shield volcanoes have _______ bases and _______ inclined slopes.

A. narrow; gently

B. broad; steeply

C. broad; gently

D. narrow; steeply

37. Which of the following is a typical plate tectonic rate (similar to the rate of

movement of the Pacific Plate at Hawaii)?

A. 100 mm/yr

B. 100 m/yr

C. 100 mi/hour

D. 100 km/ yr

MATCH THE LETTERS IN THE FIGURE WITH THE APPROPRIATE PLATE

TECTONIC FEATURES

38. San Andreas fault transform plate boundaryB

39. subduction zoneD

40. passive continental marginC

41. continental rift zoneA

42. convergent plate boundary between 2 continental platesE

THE FOLLOWING 3 QUESTIONS REFER TO THE GRAPH BELOW.

43. Mafic rocks would be found on the

A. Left side of the figure.

B. Right side of the figure

C. In the Potassium feldspar region

D. None of the above

44. Rocks that form at the LOWEST temperatures are found on the:

A. Left side of the figure.

B. Right side of the figure

C. None of the above

45. Which of the following statements is definitely FALSE.

A. Gabbro can consist of mostly olivine and pyroxene.

B. Diorite consists of pyroxene, plagioclase, and quartz.

C. Granite contains more quartz than does diorite.

D. Potassium feldspar can be a primary component of granite.

Use the letters on the right to answer the following questions.

46. Where would you crystalize mafic minerals?A

47. What part of Bowen’s Reaction series do you crystalize the LOWESTB

temperature minerals?

48. Basalt would form in what region?A

49. Diorite would form in what region?C

50. Granite would crystallize in what region? A