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Oceanography 101 - Introductory Oceanography (Lab) » Spring 2024 » Lab 2 Isostasy Post-Lab Quiz

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Question #1

What method of measuring volume could you use to measure the volume of an object that has an irregular shape, like a rock?

A. There really is no way to get the exact volume for something like a rock

B. Weigh the object on a scale

C. Displacement method by submerging in water-filled graduated container

D. Ruler method: measure the three dimensions

E. Eyeball method by comapring it several objects of known volume

F. Reconstitution method by grinding up and placing in a graduated container

Question #2

Imagine a brick that measures 20 cm long by 12 cm wide by 7 cm thick. What is the volume of the brick in cubic centimeters (cm3)

A. 1,070 cm3

B. 1,320 cm3

C. 880 cm3

D. 2,640 cm3

E. 1,940 cm3

F. 1,680 cm3

Question #3

The brick that measures 20 cm long by 12 cm wide by 7 cm thick is weighed and the scale shows a mass of 3940 grams (g). What is the density of the brick in grams per cubic centimeter (g/cm3)? Rounded to the nearest tenth.

A. 3.9 g/cm3

B. 2.9 g/cm3

C. 3.4 g/cm3

D. 4.5 g/cm3

E. 2.1 g/cm3

F. 2.4 g/cm3

Question #4

A block of wood measures 32 cm long by 14 cm wide by 2 cm thick AND has a mass of 540 grams (g). What is the density of the block in grams per cubic centimeter (g/cm3)?

A. 0.2 g/cm3

B. 0.4 g/cm3

C. 1.3 g/cm3

D. 0.9 g/cm3

E. 0.6 g/cm3

F. 1.6 g/cm3

Question #5

A piece of rock has a mass of 64 grams and displaces 24 cubic centimeters of water when placed in a graduated cylinder. What is the density of the rock in grams per cubic centimeter (g/cm3)?

A. 2.7 g/cm3

B. 3.6 g/cm3

C. 4.1 g/cm3

D. 1.8 g/cm3

E. 4.7 g/cm3

F. 22 g/cm3

Question #6

What is the density of liquid water?

A. 1.5 g/cm3

B. 2.5 g/cm3

C. 0.5 g/cm3

D. 2.0 g/cm3

E. 1.0 g/cm3

F. 3.0 g/cm3

Question #7

You measure the mass of a piece of magnetite at 81 grams. You then add 312 cm3 of water to a graduated cylinder. You place the sample into the the graduated cylinder and the water level now reads 327 cm3 Calculate the density of the magnetite sample.

A. 5.9 g/cm3

B. 5.7 g/cm3

C. 5.4 g/cm3

D. 5.1 g/cm3

E. 4.9 g/cm3

F. 4.4 g/cm3

Question #8

You measure the density of three rock samples. They had the following densities: 2.8 g/cm3 2.6 g/cm3 2.7 g/cm3 What is the average density of three rock samples? Hint: Add three up and divide total by 3.

A. 2.7 g/cm3

B. 2.8 g/cm3

C. 1.3 g/cm3

D. 2.6 g/cm3

E. 2.9 g/cm3

Question #9

What is the correct average density of the three magnetite samples in your worksheet exercise? Hint: Add up the densities of the three samples and divide the total by 3.

A. 4.6 g/cm3

B. 5.4 g/cm3

C. 4.4 g/cm3

D. 4.8 g/cm3

E. 5.0 g/cm3

F. 5.2 g/cm3

Question #10

What is the correct average density of the three granite samples in your worksheet exercise? Hint: Add up the densities of the three samples and divide the total by 3.

A. 2.7 g/cm3

B. 2.5 g/cm3

C. 3.3 g/cm3

D. 2.9 g/cm3

E. 2.3 g/cm3

F. 3.1 g/cm3

Question #11

What is the calculated volume of the Oak wood block in the worksheet exercise? Round to the nearest 1/10th (first place to the the right of the decimal point).

A. 60.9 cm3

B. 111.1 cm3

C. 90.4 cm3

D. 136.3 cm3

E. 142.4 cm3

F. 162.4 cm3

Question #12

What is the calculated density of the Oak wood block in the worksheet exercise? Round to the nearest 1/100th (second place to the the right of the decimal point).

A. 0.66 g/cm3

B. 0.85 g/cm3

C. 0.54 g/cm3

D. 0.98 g/cm3

E. 0.73 g/cm3

F. 1.18 g/cm3

Question #13

What is the calculated volume of the Pine wood block in the worksheet exercise? Round to the nearest 1/10th (first place to the the right of the decimal point).

A. 232.6.8 cm3

B. 222.6 cm3

C. 295.8 cm3

D. 315.8 cm3

E. 205.8 cm3

F. 285.8 cm3

Question #14

What is the calculated density of the Pine wood block in the worksheet exercise? Round to the nearest 1/100th (second place to the the right of the decimal point).

A. 0.71 g/cm3

B. 0.53 g/cm3

C. 1.14 g/cm3

D. 1.30 g/cm3

E. 0.89 g/cm3

F. 0.41 g/cm3

Question #15

Which crust is denser: continental or oceanic?

A. They have the same density

B. Continental

C. Oceanic

Question #16

Which crust is thicker: continental or oceanic?

A. Continental

B. Oceanic

C. They have the same thickness

Question #17

What is the most common rock type in oceanic crust?

A. Peridotite

B. Basalt

C. Shale

D. Marble

E. Granite

Question #18

What is the most common rock type in continental crust?

A. Granite

B. Sandstone

C. Shale

D. Basalt

E. Marble

Question #19

Which of the following is the most important factor in isostasy?

A. Time of day

B. Time of year

C. Density

D. Temperature

E. Thickness

Question #20

You float a wood block and find that 65% of the block is submerged underwater, and 35% sticks out of the water. What is its density? Hint: a wood block that has half in and half out has a density of 0.5 g/cm3

A. 0.65 g/cm3

B. 0.75 g/cm3

C. 0.35 g/cm3

D. 0.55 g/cm3

E. 0.85 g/cm3

F. 0.45 g/cm3

Question #21

If your Oak wood block has a density of 0.85 g/cm3, then how much of the block will stick out of the water? Hint: If the oak block had a density of 0.65 g/cm3, then 35% of the block would stick out of the water.

A. 50%

B. 35%

C. 85%

D. 65%

E. 15%

Question #22

Imagine a thick (tall) iceberg and a thin (short) iceberg, floating in water next to each other. Will the percentage of each iceberg's underwater portion (in relation to the entire iceberg) be equal or different than the other one?

A. Both icebergs will have the same percentage of it's thickness underwater.

B. There is no way to tell - no two icebergs are alike.

C. The two icebergs will have the different proportions of it's thickness underwater. - the taller one will have a greater percentage underwater than the short one.

D. The two icebergs will have the different proportions of it's thickness underwater. - the shorter one will have a greater percentage underwater than the taller one.

Question #23

How much total thickness of crust would you need to have beneath a 5-kilometer high mountain belt to hold it up? Hint: Use the 1:8 rule where every vertical kilometer of mountain needs 7 kilometers of crustal root to hold it up. However, you must add an additional 30 kilometers of crust to that value for total thickness. Note that the thickness of crust that has no mountain (like Florida) is roughly 30 kilometers.

A. 35km

B. 55km

C. 45km

D. 70km

E. 85km

Question #24

Assume that the height of a mountain belt started at an elevation of 3 kilometers above sea level. How much vertical thickness of rock must erosion remove to reduce the mountain belt down to an elevation of 1 kilometer above sea level? Assume isostatic adjustment was made to achieve isostatic equilibrium.

A. Need to erode 28 kilometers of crust to achieve new isostatic equilibrium

B. Need to erode 16 kilometers of crust to achieve new isostatic equilibrium

C. Need to erode 7 kilometers of crust to achieve new isostatic equilibrium

D. Need to erode 21 kilometers of crust to achieve new isostatic equilibrium

Question #25

During the Pleistocene geologic period, large ice sheets formed repeatedly over parts of Canada and the northern US. The most recent ice sheet reached its maximum size about 20,000 years ago, and the ice accumulated nearly two miles thick in some places. How do you think the North American continent adjusted to this massive weight?

A. Nothing happened

B. Ice age, what ice age?

C. The North American continent isostatically adjusted to the added ice thickness by sinking lower into the mantle

D. The North American continent isostatically adjusted to the added ice thickness by buoying up out of the mantle

Question #26

The large ice sheets that once covered much of North America has have now mostly melted away. - only the Greenland ice cap remains. How do you think the North American continent has adjusted to this massive loss of ice on top of it over the last 6,000 years?

A. The North American continent isostatically adjusted to the thinning/removal of the continental ice sheets by buoying up out of the mantle

B. Ice age, what ice age?

C. The North American continent isostatically adjusted to the thinning/removal of the continental ice sheets by sinking lower into the mantle

D. Nothing happened - no vertical crustal adjustments have occurred since the ice caps started to thin and disappear.

Question #27

A tall mountain belt ends its mountain building period, and now begins to erode rapidly,. What will the crust do beneath the mountain belt over time as the mountain continues to erode?

A. Start to subside

B. Just sits there.

C. Just sits there.

D. Start to uplift

Question #28

The Hawaiian Islands are volcanoes that have built upward from basaltic lava eruptions on the Pacific Ocean floor. The big island of Hawaii is actually the Earth’s tallest mountain if you measure it from its base. Interestingly, the sea floor all around Hawaii is actually deeper than average for that region of the Pacific Ocean. Why is the ocean floor around the Big Island anomalously deep?

A. The Big Island was built in an ancient asteroid crater than formed on the deep sea bottom

B. The volcano's excess mass caused the underlying ocean crust to bend downwards to isostatically compensated

C. The Big Island was built in an ancient asteroid crater than formed on the deep sea bottom

D. The ocean crust has cooled down under the Big Island to cause crust to isostatically sink.

Question #29

When a mountain range like the Himalayas grows taller and thicker, what must the base of the crust (crustal root) beneath the mountain range do to isostatcially compensate for the taller and taller mountain range?

A. The base of the crust (crustal root) essentially does nothing while the mountain grows taller.

B. The base of the crust (crustal root) essentially does nothing while the mountain grows taller.

C. The base of the crust (crustal root) becomes thicker and sits deeper into the mantle to compensate for the increased mountain mass over it.

D. The base of the crust (crustal root) becomes thinner and sits more shallow in the mantle to compensate for the increased mountain mass over it.

Question #30

What does the 1-to-8 Rule exactly mean when it comes to isostatic adjustment and equilibrium for when crust changes its thickness?

A. The 1-to-8 Rule states that if the you add 1 unit of crust onto the top of a crustal package, then you must subtract 8 units of crust from the bottom of the crust to create isostatic equlibrium to the newly thickened crustal package for a total of 7 units of subtracted crustal thickness.

B. The 1-to-8 Rule states that if the you add 7 units of crust onto the top of a crustal package, then you must add 1 unit of crust to the bottom of the crust to create isostatic equlibrium to the newly thickened crustal package for a total of 8 units of added thickness to the crust.

C. The 1-to-8 Rule states that if the you add 1 unit of crust onto the top of a crustal package, then you must add 8 units of crust to the bottom of the crust to create isostatic equlibrium to the newly thickened crustal package for a total of 9 units of added thickness to the crust.

D. The 1-to-8 Rule states that if the you add 1 unit of crust onto the top of a crustal package, then you must add 7 units of crust to the bottom of the crust to create isostatic equlibrium to the newly thickened crustal package for a total of 8 units of added thickness to the crust.

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