Physical geography; The Planet Earth - Multiple-Choice Questions and Answers

1 - The Earth is not quite spherical, because:

a. the polar radius is a little larger than the equatorial radius

b. the equatorial radius is a little larger than the polar radius

c. there are mountains in the northern hemisphere that make the surface uneven

d. there are depressions on the surface making it look more like a golfball

2 - The ocean makes up about _____ percent of the Earth's surface. a. 30

b. 45

c. 60

d. 71

e. 91

3 - The cryosphere includes _____. 

a. all forms of water on the Earth's surface

b. the highest layers of the atmosphere

c. all forms of frozen water

d. the deepest regions of the ocean

e. all of these

4 - The biosphere includes all of the following except: 

a. plants

b. animals

c. atmosphere

d. people

e. ecosystems

5 - What feature covers the largest portion of the Earth's surface? 

a. Antarctica

b. Asia

c. Africa

d. North America

e. Pacific Ocean

6 - The large, flat portion of the ocean basin at great depth is called the: 

a. ocean floor

b. ocean basement

c. abyssal plain

d. lower plains

e. Davey Jones' locker

7 - The very gently sloping, relatively shallow, submerged plain at the edge of the continent is the: 

a. continental slope

b. continental shelf

c. continental rise

d. shallow sea

8 - The deepest part of the ocean floor occurs along the: 

a. abyssal plain

b. trenches

c. middle of the Pacific

d. middle of the Indian Ocean

9 - Mid-oceanic ridges are: 

a. active volcanic features

b. found in most oceans basins

c. high, uplifted features

d. geologically active

e. all of the above

10 - Which is the largest landmass on Earth? 

a. Africa

b. Eurasia

c. North America

d. South America

e. Antarctica

11 - The hydrosphere includes the: 

a. ocean

b. atmospheric water

c. surface water

d. ground water

e. all of these

12 - Because of the shape of the Earth, you would weigh: 

a. more at the equator than at the poles because you are closer to the center of the Earth

b. more at the poles than at the equator because you are closer to the center of the Earth

c. more on a mountain top than at sea level because gravity increases with elevation

d. exactly the same at the equator as at the poles since the Earth is perfectly round

13 - This portion of the ocean consists of large and long, submarine volcanic mountain features. a. abyssal plain

b. seamounts

c. midoceanic ridges

d. Atlantis

ANSWERS:

1 - b. the equatorial radius is a little larger than the polar radius.

2 - d. 71.

3 - c. all forms of frozen water.

4 - c. atmosphere.

5 - e. Pacific Ocean.

6 - c. abyssal plain.

7 - b. continental shelf.

8 - b. trenches.

9 - e. all of the above.

10 - b. Eurasia.

11 - e. all of these.

12 - a. more at the equator than at the poles because you are closer to the center of the Earth.

13 - c. midoceanic ridges.

Review Questions and Answers; Sedimentary Rocks

1. What are the minimum and maximum sizes of sand grains?

Answer: Sand grains range in size from 1/16 mm to 2 mm.

2. The material that makes up a rock such as conglomerate cannot be deposited by a slow-flowing river. Why? 

Answer: Conglomerate cannot be deposited by a slow-flowing river because clasts larger than 2 mm are not transported by slow-moving water.

3. Describe the two main processes of lithification. 

Answer: Sediments are buried beneath other sediments where, because of the increased pressure, they become compacted and water is forced out from between the grains. With additional burial they are warmed to the point where cementing minerals can form between the grains (less than 200˚C).

4. What is the difference between a lithic arenite and a lithic wacke? 

Answer: Lithic arenite has less than 15% silt- and clay-sized particles, while a lithic wacke has more than 15%. Both have more than 10% rock fragments and more rock fragments than feldspar.

5. How does a feldspathic arenite differ from a quartz arenite? 

Answer: Feldspathic arenite has more than 10% feldspar and more feldspar than rock fragments. Quartz arenite has less than 10% feldspar and less than 10% rock fragments. Both have less than 15% silt and clay.

6. What can we say about the source area lithology, and the weathering and transportation history of a sandstone that is primarily composed of rounded quartz grains? 

Answer: Source area lithology: rock that contains quartz (such as granite or sandstone). Strong weathering is required to remove feldspar, and long fluvial transportation to round the grains.

7. What is the original source of the carbon that is present within carbonate deposits such as limestone? 

Answer: The carbon within carbonate deposits such as limestone ultimately comes from the atmosphere.

8. What long-term environmental change on Earth led to the deposition of banded iron formations? 

Answer: Most of Earth’s banded iron formations formed during the initial oxygenation of the atmosphere between 2.4 and 1.8 Ga because iron that had been soluble in the anoxic oceans became insoluble in the oxidized oceans.

9. Name two important terrestrial depositional environments and two important marine ones. 

Answer: Terrestrial depositional environments: rivers, lakes, deltas, deserts, glaciers. Marine depositional environments: continental shelves, continental slopes, deep ocean.

10. What is the origin of a foreland basin, and how does it differ from a forearc basin? 

Answer: A foreland basin forms in the vicinity of a large range of mountains where the weight of the mountains depresses the crust on either side. A forearc basin lies between a subduction zone and the related volcanic arc.

11. Explain the origins of (a) bedding, (b) cross-bedding, (c) graded bedding, and (d) mud cracks. 

Answer: (a) Bedding forms where there is an interruption or change in the depositional process, or a change in the composition of the material being deposited. (b) Cross-bedding forms in fluvial or aeolian environments where sand-sized sediments are being moved and ripples or dunes are present. (c) Graded bedding forms when transport energy decreases, depositing finer and finer particles. (d) Mud cracks form where fine-grained sediments (silt or clay) are allowed to dry.

12. Under what conditions will reverse-graded bedding form? 

Answer: Reverse-graded bedding forms during gravity flows, such as debris flows.

13. What are the criteria for the application of a formation name to a series of sedimentary rocks?

Answer: A formation is a series of beds that is distinct from other beds above and below it, and is thick enough to be shown on the geological maps that are widely used within the area in question.

14. Explain why some of the Nanaimo Group formations have been divided into members, while others have not.

Answer: The Nanaimo Group was actively mined for coal for many decades. During that time the names were given to members and individual beds that were important to the coal miners.

Review Questions and Answers; Metamorphism and Metamorphic Rocks

1. What are the two main agents of metamorphism, and what are their respective roles in producing metamorphic rocks?

Answer: Heat and pressure are the main agents of metamorphism. Heat leads to mineralogical changes in the rock. Pressure also influences those mineralogical changes, while directed pressure (greater pressure in one direction) leads to foliation.

2. What types of metamorphic rocks will form if a mudrock experiences very low, low, medium, and high-grade metamorphism? 

Answer: Very low grade: slate; low grade: phyllite; medium grade: schist; high grade: gneiss.

3. Why doesn’t granite change very much at lower metamorphic grades? 

Answer: Granite remains largely unchanged at lower metamorphic grades because its minerals are still stable at those lower temperatures.

4. Describe the main process of foliation development in a metamorphic rock such as schist. 

Answer: Foliation develops in schist when new platy minerals grow with their longest dimension at a right angle to the direction of greatest pressure.

5. What process contributes to metamorphism of oceanic crust at a spreading ridge? 

Answer: At a spreading ridge the heat from volcanism leads to the development of a groundwater convection system in the rock of the oceanic crust. Heated water rises in the hot regions and is expelled into the ocean, while cold ocean water is drawn into the crust to replace it. The heated water leads to the conversion of olivine and pyroxene into chlorite and serpentine.

6. How do variations in the geothermal gradient affect the depth at which different metamorphic rocks form?

Answer: The geothermal gradient varies as a function of tectonic setting, being greatest in volcanic regions and lowest along subduction zones. As a result the depth at which specific metamorphic grades is achieved will vary: the depth will be greater when the gradient is lower.

7. Blueschist metamorphism takes place within subduction zones. What are the particular temperature and pressure characteristics of this geological setting? 

Answer: The geothermal gradient is low within subduction zones because the cold subducting oceanic crust takes a long time to heat up. Pressure increases with depth at the normal rate, but temperature does not.

8. Rearrange the following minerals in order of increasing metamorphic grade: biotite, garnet, sillimanite, chlorite. 

Answer: Order of increasing metamorphic grade: chlorite, biotite, garnet, sillimanite.

9. What is the role of magmatic fluids in the metamorphism that takes place adjacent to a pluton? 

Answer: Water from any source facilitates metamorphism. Magmatic fluids typically contain dissolved ions at higher concentrations than in regular groundwater (especially copper, zinc, silver, gold, lithium, beryllium, boron and fluorine), leading to the formation of a unique set of minerals.

10. How does metasomatism differ from regional metamorphism? 

Answer: Metasomatism involves fluids from magmatic or groundwater sources that play an important role in transporting ions into the system, and leading to the formation of new minerals. Regional metamorphism takes place over a larger area, depends more on plate tectonic conditions, and does not involve flushing the system with large amounts of fluid.

11. How does the presence of a hot pluton contribute to metasomatism? 

Answer: A hot pluton heats the surrounding water, causing groundwater to convect. This can result a great deal of water, in some cases with elevated levels of specific ions, passing through the rock. Water from magma within the pluton also contributes to metasomatism.

12. What determines whether metasomatism will produce skarn? 

Answer: Limestone must be present to produce skarn.

13. For each of the following metamorphic rocks, indicate the likely parent rock and the grade and/or type of metamorphism: chlorite schist, slate, mica-garnet schist, amphibolite, marble.

Answer: Parent rocks and metamorphic grades and types:

Practice Questions and Answers: Metamorphic Rocks

1. Base your answer to the following question on the information below.

A student on a field trip in New York State collected a sample of metamorphic bedrock containing bands of coarse-grained crystals of plagioclase feldspar, pyroxene, quartz, and mica.

Identify the metamorphic rock found by the student.

2. Which rock is only formed by regional metamorphism?

A) slate 

B) hornfels 

C) dunite 

D) marble

3. Base your answer to the following question on the geologic cross section below. Location A is within the metamorphic rock.

The metamorphic rock at location A is most likely

A) marble 

B) quartzite 

C) phyllite 

D) slate

4. Wavy bands of light and dark minerals visible in gneiss bedrock probably formed from the

A) cementing together of individual miner grains 

B) cooling and crystallization of magma 

C) evaporation of an ancient ocean 

D) heat and pressure during metamorphism

5. Base your answer to the following question on The rock shown below has a foliated texture and contains the minerals amphibole, quartz, and feldspar arranged in coarse-grained bands.

Which rock is shown?

A) slate 

B) dunite 

C) gneiss 

D) quartzite

6. Base your answer to the following question on the graph below, which shows the crustal temperature and pressure conditions under which three different minerals with the same chemical composition (Al2SiO5) crystallize.

Under which crustal temperature and pressure conditions will andalusite form?

A) 300°C and 6000 atmospheres 

B) 500°C and 2000 atmospheres 

C) 600°C and 4000 atmospheres 

D) 700°C and 8000 atmospheres

7. Which physical characteristic best describes the rock phyllite?

A) glassy texture with gas pockets 

B) clastic texture with angular fragments 

C) bioclastic texture with cemented shell fragments 

D) foliated texture with microscopic mica crystals

8. During the Permian Period, sedimentary bedrock in the Appalachian Region was subjected to high temperature and pressure. Calcite deposits that had existed in this environment would most likely have formed

A) schist 

B) gabbro 

C) marble 

D) gneiss

9. Which nonfoliated rock forms only in a zone of contact metamorphism?

A) conglomerate 

B) hornfels 

C) pegmatite 

D) quartzite

10. Which rock is foliated, shows mineral alignment but not banding, and contains medium-sized grains of quartz and pyroxene?

A) phyllite 

B) schist 

C) gneiss 

D) quartzite

11. The diagram below shows four rock samples.

Which sample best shows the physical properties normally associated with regional metamorphism?

A) A 

B) B 

C) C 

D) D

12. Which sequence of change in rock type occurs as shale is subjected to increasing heat and pressure?

A) shale → schist → phyllite → slate → gneiss 

B) shale → slate → phyllite → schist → gneiss 

C) shale → gneiss → phyllite → slate → schist 

D) shale → gneiss → phyllite → schist → slate

13. How do the metamorphic rocks schist and quartzite differ?

A) Quartzite contains the mineral quartz and schist does not. 

B) Quartzite forms from regional metamorphism and schist does not. 

C) Schist is organically formed and quartzite is not. 

D) Schist is foliated and quartzite is not.

14. Base your answer to the following question on the cross section below which shows the surface and subsurface rock formations near New York City.

A) Palisades sill 

B) Fordham gneiss 

C) Inwood marble 

D) Manhattan schist

15. The diagram below represents a rock with a distorted layer structure.

The distorted structure of this rock is most likely the result of

A) a long period of weathering 

B) glacial activity 

C) wind erosion 

D) extreme pressure

Answer Key

1. gneiss 

2. A 

3. B 

4. D 

5. C 

6. B 

7. D 

8. C 

9. B 

10. B 

11. A 

12. B 

13. D 

14. C 

15. D