Question 1

In the figure below, which direction is the longshore drift?

Accepted Answer

The answer of In the figure below, which direction is...

Question 2

In the photograph below, notice how the waves are approaching the shore at an angle to the shoreline. This is an example of

Accepted Answer

The fact that the waves are approaching the shore at an angle to the shoreline indicates that they are being refracted, or bent, as they encounter a change in water depth or bottom structure. This is a common phenomenon that occurs when waves encounter headlands, bays, or other obstructions along a coastline. The refraction of waves causes them to undergo changes in speed, direction, and wavelength, which can affect their intensity and ability to erode or deposit sediments along the shore.

Question 3

Many rocky coasts occur along active margins. This is because

Accepted Answer

Active margins are characterized by tectonic activity, including plate subduction and uplift, which can create steep and rocky coasts. The repeated uplift can prevent waves from eroding the land surface down to sea level, resulting in rocky coasts. Additionally, subduction along active margins can consume coastal sediments, further limiting the supply of sediment for beach formation. However, this does not necessarily mean that active margins have fewer beaches overall, as beach formation can also occur through other processes such as longshore drift.

Question 4

What will eventually happen to the headlands in the figure below?

Accepted Answer

The answer of What will eventually happen to the headlands...

Question 5

A coastline characterized by steep-sided cliffs and associated with an active margin is likely to be

Accepted Answer

Emergent coastlines are associated with active margins where tectonic activity, such as uplift, can create steep-sided cliffs. This contrasts with submergent coastlines, which are typically associated with rising sea levels or subsidence.

Question 6

Which type of coastline would most likely contain estuaries or fjords?

Accepted Answer

Estuaries and fjords are formed due to submergent coastlines, caused by a rise in sea level or subsidence of the land. As the sea level rises, the water floods the river valleys creating estuaries. Fjords are formed by glacial erosion in a submergent coastline. Subductive coastlines are characterized by deep sea trenches and volcanic islands. Emergent coastlines are formed due to upliftment of land or a drop in sea level. Divergent coastlines are characterized by mid-ocean ridges and volcanic islands.

Question 7

When the sea level rises, an ocean may invade a river valley, producing a nearshore body of water of mixed and variable salinity, which is termed a(n)

Accepted Answer

An estuary is a semi-enclosed body of water where freshwater meets saltwater, typically formed where a river meets the ocean. As sea levels rise, an estuary may form in a river valley where the seawater mixes with freshwater to form a body of water with mixed and variable salinity. Choices A, B, and D are not accurate descriptions of this type of body of water. An atoll is a ring-shaped coral reef that surrounds a lagoon, but it is not typically formed from sea level rise. A lagoon is a shallow body of water separated from the ocean by a barrier island, reef, or spit, and it is not necessarily formed by sea level rise. Finally, a jetty is a man-made structure built to protect a harbor or shoreline, but it is not a type of body of water.

Question 8

A(n) __________ is a vegetated, flat-lying stretch of coast that floods at high tide, becomes particularly exposed at low tide, and does not feel the impact of strong waves.

Accepted Answer

A coastal wetland is a vegetated area along the coast that is flooded during high tide and exposed during low tide. It is typically protected from strong waves by other coastal features such as barrier islands or dunes. Marine terraces are typically higher and more rocky, and can feel the impact of waves. Coral reefs are also not typically flat lying, and can be exposed to strong waves. Estuaries are areas where freshwater and saltwater mix, and are not necessarily vegetated or exposed at low tide.

Question 9

Barrier islands are constantly moving in the direction of

Accepted Answer

Barrier islands are formed by sediment deposited by longshore drift, which is the movement of sediment along the coast by the action of waves approaching the shoreline obliquely. As a result, barrier islands move in the direction of longshore drift.

Question 10

The entire state of Florida is composed of fossiliferous limestone (indicative of a coral reef environment). This implies that in the recent past, Florida was

Accepted Answer

Fossiliferous limestone is indicative of a coral reef environment that forms in shallow, warm waters. The fact that the entire state of Florida is composed of this limestone indicates that it was submerged under the sea in the recent past, making it a submergent coast.

Question 11

Which of the following is the BEST example of an organic coast?

Accepted Answer

A shallow coral reef is the best example of an organic coast because it is formed by living organisms such as corals, algae, and other marine life. It is a natural and dynamic system that provides habitat for many species and protects the shoreline from erosion. The other choices (A, B, and C) are more related to geologic processes and human interventions rather than biological processes.

Question 12

If sea level continues to rise and covers the city of Miami, the Florida coast will become a(n)

Accepted Answer

If sea level continues to rise and covers the city of Miami, the Florida coast will become a submergent coast, meaning that the land will be inundated by the rising sea level.

Question 13

A coral reef would MOST likely be found

Accepted Answer

Coral reefs are most likely to be found in warm, shallow waters surrounding tropical islands. These waters generally have clear visibility and high temperatures, which are necessary for the growth of corals. Volcanic islands are especially conducive to coral growth because the nutrient-rich water supports the diverse array of marine life that helps build the reef structure. Tidal flats are characterized by muddy sediments that are not suitable for coral growth, while high-latitude waters are often too cold for coral reefs to form. Active margins, where tectonic plates are colliding, are more likely to have steep drop-offs and strong currents that make it difficult for coral reefs to thrive.

Question 14

In the figure below, which direction is the longshore current?

Accepted Answer

The answer of In the figure below, which direction is...

Question 15

Along beaches, groins have

Accepted Answer

Groins are structures built perpendicular to the shore in order to reduce beach erosion. However, they can cause increased erosion rates immediately down current from the groin, as they disrupt the natural movement of sediment along the beach. This can lead to a buildup of sediment up current from the groin, but a decreased supply of sediment down current from the groin, resulting in erosion.

Question 16

The balance between sediment supplied and sediment removed on a beach is known as

Accepted Answer

The balance between sediment supplied and sediment removed on a beach is referred to as the sediment budget. This takes into account the sources of sediment such as rivers, cliffs, and offshore deposits, as well as the processes that remove sediment such as wave erosion, longshore drift, and storms. By evaluating the sediment budget, researchers can better understand how a beach is evolving over time, and whether it is stable or eroding.

Question 17

Sea level is currently rising at 3.2 mm/yr, and scientists predict that global warming could cause a rise in sea level of 7 m if left unabated. How long will it take the sea to rise 7 m at the current rate?

Accepted Answer

To find the time it takes for the sea to rise 7 meters at a rate of 3.2 mm/year, convert 7 meters to millimeters (7,000 mm) and divide by the rate: 7,000 mm / 3.2 mm/year = 2,187.5 years. However, the closest choice is 2,121 years, which is likely a rounding or approximation error.

Question 18

Which of the following features is characteristic of a rocky coast?

Accepted Answer

Sea stacks are towering columns of rock that are separated from the coast by erosion from waves and wind. This is a characteristic feature of a rocky coast. Sand spits, lagoons, and accretionary prisms are more commonly associated with sandy coasts.

Question 19

Which of the following scenarios is most likely to result in an emergent coast?

Accepted Answer

An emergent coast is formed when the land rises relative to sea level. This can happen due to uplift associated with active margin tectonics, such as along a continental collision zone or subduction zone. The other options, global sea level rise, subsidence caused by groundwater removal, and the formation of a coral reef, would all lead to a submergent coast, where the land is being inundated by rising sea levels or sinking relative to sea level.

Question 20

A coast that grows seaward as a result of regular sedimentation is a(n)

Accepted Answer

An accretionary coast is a coast that grows seaward as a result of regular sedimentation. This can occur due to deposition from rivers or ocean currents, and it results in the gradual expansion of the land mass in the coastal zone. Active continental margins, on the other hand, are characterized by tectonic activity and the formation of mountains and volcanic arcs. Erosional coasts are characterized by the gradual retreat of the shoreline due to wave erosion, while coastal plains are low-lying areas that are relatively flat and adjacent to the ocean.

Quiz 16: Marine Geology: the Study of Ocean Basins and Coasts