Question 1 Read the descriptions of the features labeled on this figure in the Chapter 9 Investigation in your textbook and determine the order in which the rocks and geologic features formed (e.g.,...

Question 1

Read the descriptions of the features labeled on this figure in the Chapter 9 Investigation in your textbook and determine the order in which the rocks and geologic features formed (e.g., make a list of the letters from oldest to youngest).
What is the oldest rock unit in the area?


Answer

tan sandstone (A)

greenish shale (B)

dike (D)

granite (G)

gray limestone (K)

1 points


Question 2

Indicate the relative age of these three rock units, with 1 being the oldest of the three and 3 being the youngest.


Answer
tan sandstone (A)
greenish shale (B)
coarse sandstone (C)
1 points


Question 3

Indicate the relative age of these three rock units, with 1 being the oldest of the three and 3 being the youngest.
Answer
tan sandstone (A)
gray limestone (K)
reddish sandstone (S)
1 points


Question 4

Indicate the relative age of these three rock units, with 1 being the oldest of the three and 3 being the youngest.
Answer
greenish shale (B)
granite (G)
volcano (V) and lava flow (L)
1 points


Question 5

Indicate the relative age of these four geologic events, with 1 being the oldest of the four, and 4 being the youngest.
Answer
formation of the dike (D)
movement along the fault (F)
deposition of older river gravels (R)
eruptions forming the volcano (V) and lava flow (L)
1 points


Question 6

How did the unconformity between the granite (G) and overlying coarse sandstone (C) form?
Answer

Magma rose into the crust, stopping at the base of the sandstone and baking the sandstone.

The sandstone was eroded into a gentle landscape, and then the granite came in later.

Faulting or folding placed the sandstone over the top of the granite.

The granite formed at depth and was uplifted and eroded, and the sandstone was deposited on top.

1 points


Question 7

The Chapter 9 Investigation in the textbook has a table of fossils and their geologic period. Based on this table, which rock unit contains the oldest fossils?
Answer

tan sandstone (A)

greenish shale (B)

coarse sandstone (C)

gray limestone (K)

older river gravels (R)

reddish sandstone (S)

1 points


Question 8

Use the data in the following table to calculate the number of half lives that have passed since the granite (G) formed. How many half lives have passed?
Answer

1
2
3
4
5
250
500
750

0.5 points


Question 9

Using the number of half lives that have passed since the granite (G) formed and the half life of the isotope used in dating the granite, what is the age of the granite?
Answer

1 million years

2 million years

50 million years

250 million years

1,000 million years (1 billion years)

2,000 million years (2 billion years)

0.5 points


Question 10

Use the data in the following table to calculate the number of half lives that have passed since the dike (D) formed. How many half lives have passed?
Answer

1
2
3
4
5
250
500
750

1 points


Question 11

Using the number of half-lives that have passed since the dike (D) formed and the half-life of the isotope used in dating the dike, what is the age of the dike?
Answer

1 million years

2 million years

50 million years

250 million years

1,000 million years (1 billion)

2,000 million years (2 billion)

Below is a virtual ocean with several features depicted on the ocean floor. Match the name for each feature using the choices provided.
Answer

Feature A Read Answer Items for Question 1 Feature B Read Answer Items for Question 1 Feature C Read Answer Items for Question 1 Feature D Read Answer Items for Question 1 Feature E Read Answer Items for Question 1 Feature F Read Answer Items for Question 1 Feature G Read Answer Items for Question 1 Feature H Read Answer Items for Question 1 Feature I Read Answer Items for Question 1 Feature J Read Answer Items for Question 1 Feature K Read Answer Items for Question 1

Answer A. island arc B. back-arc basin C. submarine canyon and fan D. oceanic fracture zone E. passive margin with relatively wide continental shelf F. probable location of hot spot G. oceanic plateau H. abyssal plain I. passive continental margin with narrow continental shelf J. oceanic trench K. mid-ocean ridge

2 points


Question 2

For each of the labeled features, match the name of the feature with the appropriate description of how that feature formed.
Answer

oceanic trench Read Answer Items for Question 2 island arc Read Answer Items for Question 2 oceanic plateau Read Answer Items for Question 2 linear island chain Read Answer Items for Question 2 submarine canyon and fan Read Answer Items for Question 2 continental shelf Read Answer Items for Question 2 back-arc basin Read Answer Items for Question 2 abyssal plain Read Answer Items for Question 2 mid-ocean ridge Read Answer Items for Question 2 fracture zone Read Answer Items for Question 2

Answer A. Two oceanic plates diverge, allowing mantle to rise, melt, and form new oceanic crust. B. Formed where two oceanic plates converge, and melting caused by the subducted plate results in volcanoes on the overriding plate. C. A rising plume of mantle melts and causes melting of adjacent lithosphere, and magma erupts onto the seafloor. D. Differences in the age of seafloor cause oceanic crust on one side of this feature to be higher in elevation than oceanic crust on the other side, but the feature is not a plate boundary. E. Formed by bending down of a slab as it enters a subduction zone. F. Sediment is transported by turbidity currents from the edge of the continent into deeper water. G. Migration of an island arc and trench causes oceanic crust behind the arc to stretch, rift, and spread. H. Movement of a plate over a hot spot results in a linear chain of volcanic islands and seamounts. I. Cooling of the lithosphere causes subsidence of oceanic crust, which is then covered by deep-water sediments. J. A broad area of continental crust that has been thinned and overlain by marine sediments.

2 points


Question 3

What possible relationship exists between features B and C? Choose the
best
answer from the descriptions provided.
Answer

Two oceanic plates diverge, forming a rift, which allows magma to reach the surface.

Oceanic crust is subducted and releases water, which causes magma to rise into the overriding plate.

A rising mantle plume causes widespread melting when it first encounters the lithosphere; magmatism continues as the plate moves over the hot spot.

Spreading causes two plates to slip past one another along transform faults; differences in elevation reflect differences in the age of the crust.

0.5 points


Question 4

What possible relationship exists between features E and F? Choose the
best
answer from the descriptions provided.
Answer

Two oceanic plates diverge, forming a rift, which allows magma to reach the surface.

Oceanic crust is subducted and releases water, which causes magma to rise into the overriding plate.

A rising mantle plume causes widespread melting when it first encounters the lithosphere; magmatism continues as the plate moves over the hot spot.

Two oceanic plates converge along an irregular boundary, which causes tears and wrinkles in the crust.

0.5 points


Question 5

What possible relationship exits between features J and K? Choose the
best
answer from the descriptions provided.
Answer

Oceanic crust is subducted and releases water, which causes magma to rise into the overriding plate.

Turbidity currents scour deeply into oceanic crust in the middle of the ocean, causing grooves and ridges.

Spreading causes two plates to slip past one another along transform faults; differences in elevation reflect differences in the age of the crust.

Two oceanic plates converge along an irregular boundary, which causes tears and wrinkles in the crust.

0.5 points


Question 6

Based on the features you identified on the ocean floor, choose the most appropriate cross section from those presented below.
Answer

Cross section A

Cross section B

Cross section C

Cross section D

1 points


Question 7

Where was the oceanic plateau relative to the hot spot 20 million years ago? Choose the most appropriate answer from the list below.
Answer

Farther away from the hot spot.

Same distance away from the hot spot.

Closer to the hot spot.

On top of the hot spot.

0.5 points


Question 8

What was the length of the linear chain of islands 20 million years ago? Choose the most appropriate answer from the list below.
Answer

Longer than today.

Same length as today.

Half as long as today.

It did not yet exist.

0.5 points


Question 9

Which way is the plate on which the oceanic plateau rests moving relative to the hot spot at depth (assume that on the main figure you are looking north)? Choose the most appropriate answer from the list below.
Answer

west

northwest

north

northeast

south

southwest

east southeast

0.5 points


Question 10

How wide was the narrow sea between the western continent and adjacent volcanic islands 20 million years ago? Choose the most appropriate answer from the list below.
Answer

Wider than it is today.

Same width as it is today.

A little narrower than it is today.

Much narrower than it is today.

0.5 points


Question 11

How wide was the narrow ocean between the central and eastern continents 20 million years ago? Choose the most appropriate answer from the list below.
Answer

Wider than it is today.

Same width as it is today.

A little narrower than it is today.

Much narrower than it is today.

0.5 points


Question 12

How wide do you think the narrow ocean between the central and eastern continents will be 20 million years in the future? Choose the most appropriate answer from the list below.
Answer

Nearly twice as wide as it is today.

A little wider than it is today.

The same width as it is today.

Much narrower than it is today.

0.5 points


Question 13

What do you think might happen to the oceanic plateau 20 million years into the future? Choose the most appropriate answer from the list below.
Answer

It may become much larger than it is today.

It may collide with and become part of the central continent.

It may subside and become part of the abyssal plain.

It may collide with the trench.