1.
The element found in some sediments which suggest that a meteorite or asteroid impact
occurred nearby is:
Correct Answer
B. B) iridium.
Explanation
Iridium is the correct answer because it is an element that is rare in the Earth's crust but abundant in meteorites and asteroids. The presence of iridium in sediments suggests that a meteorite or asteroid impact occurred nearby, as these extraterrestrial objects contain high levels of iridium. Uranium, manganese, and strontium are not directly associated with meteorite or asteroid impacts.
2.
"Black smokers" are associated with ________.
Correct Answer
D. D) all of these
Explanation
"Black smokers" are hydrothermal vents found along oceanic ridges. These vents emit hot water that is rich in minerals. Therefore, the correct answer is D) all of these, as they are associated with oceanic ridges, hot water, and mineral-rich waters.
3.
The oceans cover approximately ________ percent of Earth's surface.
Correct Answer
A. A) 70
Explanation
The correct answer is A) 70. This means that approximately 70 percent of Earth's surface is covered by oceans. This is a significant percentage, indicating that the majority of the Earth's surface is made up of water bodies. The oceans play a crucial role in regulating the Earth's climate, supporting diverse ecosystems, and providing resources for human populations.
4.
Which one of the following concerning mid-ocean ridges is false?
Correct Answer
D. D) sediments include thick siliceous ooze deposits and sandy turbidite beds
Explanation
Mid-ocean ridges are sites for submarine eruptions of basaltic lava and where young lithosphere is added to the edges of spreading, oceanic plates. Additionally, terrigenous sediment coverings are very thin or absent. However, sediments in mid-ocean ridges do not include thick siliceous ooze deposits and sandy turbidite beds.
5.
Which of the following contains calcium carbonate (CaCO3)?
Correct Answer
E.
E) foraminiferans
Explanation
Foraminiferans are microscopic marine organisms that have shells made of calcium carbonate (CaCO3). These shells accumulate on the ocean floor over time and can form limestone deposits. Therefore, foraminiferans contain calcium carbonate.
6.
The most likely place to find abundant manganese nodules is on the:
Correct Answer
A. A) abyssal plain far from a continent.
Explanation
Manganese nodules are typically found on the abyssal plain, which is a flat and deep region of the ocean floor far from any continents. This is because the formation of manganese nodules requires specific conditions, such as low sedimentation rates, slow growth rates, and a stable environment, which are more likely to be found in the abyssal plain. The continental rise, crest of a mid-ocean ridge, and continental shelf are not as suitable for the formation of manganese nodules due to different geological and environmental factors. Therefore, the most likely place to find abundant manganese nodules is on the abyssal plain far from a continent.
7.
Minerals that crystallize directly from seawater are examples of ________.
Correct Answer
A. A) hydrogenous sediment
Explanation
Minerals that crystallize directly from seawater are known as hydrogenous sediment. These minerals form through the process of precipitation from the seawater itself. This is in contrast to biogenous sediment, which is made up of organic material from living organisms, and terrigenous sediment, which consists of particles eroded from land. Therefore, the correct answer is A) hydrogenous sediment.
8.
Submarine canyons form the deepest parts of the ocean basins.
Correct Answer
B. False
Explanation
Submarine canyons do not form the deepest parts of the ocean basins. The deepest parts of the ocean basins are actually found in areas called trenches, which are long, narrow depressions on the seafloor. Submarine canyons, on the other hand, are steep-sided valleys that cut into the continental slope. While they can be quite deep, they are not typically as deep as trenches. Therefore, the statement that submarine canyons form the deepest parts of the ocean basins is false.
9.
Manganese nodules do not accumulate below 4500 meters depth because the manganese
minerals are highly soluble in seawater below that depth.
Correct Answer
B. False
Explanation
Manganese nodules do accumulate below 4500 meters depth because the manganese minerals are not highly soluble in seawater below that depth.
10.
Compared to the Southern Hemisphere, a higher percentage of the Northern Hemisphere is
water covered.
Correct Answer
B. False
Explanation
The statement is false because a higher percentage of the Southern Hemisphere is water covered compared to the Northern Hemisphere. The Southern Hemisphere has a larger proportion of its surface covered by water due to the presence of large oceans like the Pacific, Atlantic, and Indian Ocean. In contrast, the Northern Hemisphere has a greater landmass with continents like North America, Europe, and Asia. Therefore, the Southern Hemisphere has a higher percentage of water coverage.
11.
The continental rise lies at the bottom of the continental slope.
Correct Answer
A. True
Explanation
The continental rise is a feature that occurs at the bottom of the continental slope. It is formed by the accumulation of sediment that has been transported down the slope by gravity. As the sediment reaches the base of the slope, it spreads out and forms the continental rise. Therefore, it is true that the continental rise lies at the bottom of the continental slope.
12.
Sand, silt, and clays deposited on the ocean floor are described as terrigenous sediments
Correct Answer
A. True
Explanation
Terrigenous sediments are formed from weathered rocks on land that are transported to the ocean by rivers, wind, or glaciers. These sediments can include sand, silt, and clay particles. Therefore, it is correct to say that sand, silt, and clays deposited on the ocean floor are described as terrigenous sediments.
13.
A pelagic clay contains lots of material that settles to the seafloor through the water column and
are:
Correct Answer
E. E) less than 30% neritic material.
Explanation
A pelagic clay contains lots of material that settles to the seafloor through the water column. The correct answer, E) less than 30% neritic material, suggests that the pelagic clay does not contain a significant amount of material from the neritic zone, which is the shallow, nearshore area of the ocean. This indicates that the majority of the material in the pelagic clay comes from other sources, such as the open ocean or deeper parts of the ocean.
14.
The crests of mid-oceanic ridges ________.
Correct Answer
D. D) contain active rift zones
Explanation
The correct answer is D) contain active rift zones. Mid-oceanic ridges are underwater mountain ranges where tectonic plates are moving apart. These ridges are characterized by the presence of active rift zones, where new crust is being formed through volcanic activity. This volcanic activity leads to the creation of new oceanic crust and the formation of rift valleys. Therefore, the crests of mid-oceanic ridges contain active rift zones.
15.
Which of the following is associated with ocean ridges?
Correct Answer
D. D) all of these
Explanation
Ocean ridges are associated with all of the given options. Rift zones are areas where tectonic plates are moving apart, creating a gap that is filled with magma from the mantle, resulting in volcanic activity. This volcanic activity leads to the formation of volcanic structures such as underwater volcanoes and seamounts. The continuous movement of the tectonic plates also creates mountainous topography along the ocean ridges, with underwater mountains and ridges being formed. Therefore, all of the given options are associated with ocean ridges.
16.
Which of the following is not an important control on oceanic sediment accumulation?
Correct Answer
E. E) All of the above factors are important.
Explanation
All of the factors mentioned in options A, B, C, and D are important controls on oceanic sediment accumulation. The degree of preservation determines how well the sediment is preserved over time, the rate of deposition influences the amount of sediment that accumulates, input from other sediment types can affect the composition of the sediment, and dilution can influence the concentration of sediment in the water. Therefore, all of these factors play a role in controlling oceanic sediment accumulation.
17.
Concerning the distribution of land and water, which of the following statements is true?
Correct Answer
A. A) the Southern HemispHere has much more water surface than the Northern HemispHere
Explanation
The correct answer is A) the Southern Hemisphere has much more water surface than the Northern Hemisphere. This is because the Southern Hemisphere has a larger proportion of its surface covered by oceans, with the Pacific Ocean and the Atlantic Ocean being the largest. In contrast, the Northern Hemisphere has a larger proportion of its surface covered by landmasses, including the continents of North America, Europe, and Asia. Therefore, the Southern Hemisphere has a greater amount of water surface compared to the Northern Hemisphere.
18.
Which one of the following salts is most abundant in seawater?
Correct Answer
A. A) sodium chloride
Explanation
Sodium chloride is the most abundant salt in seawater because it is the primary component of saltwater and is present in high concentrations. It is formed when sodium ions from sodium hydroxide react with chloride ions from hydrochloric acid. Sodium chloride is essential for various biological processes and is commonly used for seasoning and preserving food.
19.
Submarine canyons found on the continental slope and are believed to have been created
________.
Correct Answer
D.
D) none of these
Explanation
The given answer states that submarine canyons found on the continental slope were not created by any of the options provided in the question. This means that the correct explanation for the creation of submarine canyons is not mentioned in the options given. Therefore, the answer is none of these.
20.
Submerged, flat-topped seamounts are known as guyots.
Correct Answer
A. True
Explanation
Guyots are submerged, flat-topped seamounts that were once volcanic islands. Over time, erosion and subsidence caused them to sink beneath the ocean surface. The flat top of a guyot is typically the result of wave action and coral reef growth when the seamount was still above water. Therefore, the statement that submerged, flat-topped seamounts are known as guyots is true.
21.
Seafloor hot springs occur mainly in oceanic, abyssal plains.
Correct Answer
B. False
Explanation
Seafloor hot springs, also known as hydrothermal vents, do not occur mainly in oceanic abyssal plains. They are actually found in various locations such as mid-ocean ridges, volcanic arcs, and back-arc basins. These hydrothermal vents are formed when seawater seeps into the seafloor and is heated by magma, creating hot springs that release mineral-rich fluids and support unique ecosystems.
22.
The Atlantic and Pacific basins have oceanic ridges; the Indian Ocean has no oceanic ridge
Correct Answer
B. False
Explanation
The statement is false because the Indian Ocean does have an oceanic ridge known as the Mid-Indian Ridge. This underwater mountain range runs through the Indian Ocean and is a site of tectonic activity, similar to the oceanic ridges found in the Atlantic and Pacific basins. Therefore, the statement that the Indian Ocean has no oceanic ridge is incorrect.
23.
Turbidites and siliceous oozes are both biogenous sediments.
Correct Answer
B. False
Explanation
The statement is false because turbidites are not biogenous sediments. Turbidites are actually a type of sedimentary rock that is formed from the deposition of sediment carried by turbidity currents. These currents are fast-moving underwater avalanches that transport and deposit a mixture of different types of sediments, including both biogenous and non-biogenous materials. On the other hand, siliceous oozes are biogenous sediments that are primarily composed of the remains of siliceous organisms such as diatoms and radiolarians. Therefore, while siliceous oozes are biogenous sediments, turbidites are not.
24.
The surface waters in regions where evaporation rates are high, such as the Red Sea, have higher
than average salinities
Correct Answer
A. True
Explanation
In regions with high evaporation rates, such as the Red Sea, the water evaporates quickly, leaving behind the dissolved salts and minerals, which increases the salinity of the remaining surface water. This is why the surface waters in these regions have higher than average salinities.
25.
The BEST definition of the outer edge of the continental shelf is that point where ________.
Correct Answer
B. B) the water depth reaches 100 fathoms
Explanation
The outer edge of the continental shelf is defined as the point where the water depth reaches 100 fathoms. This means that as we move away from the shore, the depth of the water gradually increases until it reaches 100 fathoms, indicating the end of the continental shelf. This definition helps to distinguish the continental shelf from the deeper oceanic waters beyond.
26.
Which one of the following would you NOT associate with turbidity currents?
Correct Answer
C. C) formation of seamounts
Explanation
Turbidity currents are fast-moving currents that transport sediment and can cause erosion. They are typically associated with the excavation of submarine canyons and the deposition of graded beds. Density currents, which are caused by differences in water density, can generate turbidity currents. However, the formation of seamounts is not typically associated with turbidity currents. Seamounts are underwater mountains that are formed by volcanic activity, not by the movement of sediment in turbidity currents.
27.
________ diatom ooze
Correct Answer
A. A. biogenous
Explanation
The given answer is "a. biogenous". Diatom ooze is a type of sediment that is primarily composed of the remains of diatoms, which are microscopic algae with hard silica shells. These diatoms live in marine environments and when they die, their shells sink to the ocean floor and accumulate over time, forming diatom ooze. Since diatoms are living organisms, the sediment derived from their remains is considered biogenous.
28.
________ quartz sand
Correct Answer
B. B. terrigenous
Explanation
Terrigenous refers to sediments that originate from the land, such as weathered rock fragments, minerals, and organic material that are transported by rivers, wind, or glaciers and eventually deposited in the ocean. Quartz sand is a type of terrigenous sediment that is composed mainly of quartz grains. This explanation aligns with the given correct answer, "b. terrigenous."
29.
________ calcareous ooze
Correct Answer
A. A. biogenous
Explanation
Calcareous ooze refers to sediment that is primarily composed of the remains of marine organisms such as shells and skeletal fragments. These organisms produce calcium carbonate, which accumulates on the ocean floor over time. Therefore, the correct answer is "a. biogenous" as it accurately describes the origin of calcareous ooze from biological sources.
30.
________ abyssal plain clay
Correct Answer
B.
b. terrigenous
Explanation
Terrigenous refers to sediment that is derived from the land and transported to the ocean by rivers, wind, or glaciers. Abyssal plain clay is primarily composed of terrigenous sediment that has settled on the ocean floor over long periods of time. This sediment is typically made up of fine particles, such as clay, that have been weathered and eroded from rocks on land. Therefore, the correct answer is b. terrigenous.
31.
________ turbidite deposits
Correct Answer
B. B. terrigenous
Explanation
Turbidite deposits are sedimentary deposits that form from turbidity currents, which are underwater avalanches of sediment. These currents are mainly composed of terrigenous sediments, which are derived from the erosion of land and transported by rivers and wind. Therefore, the correct answer is b. terrigenous.
32.
________ manganese nodule
Correct Answer
C.
c. hydrogenous
Explanation
The term "manganese nodule" refers to a type of rock formation that is primarily composed of manganese and other minerals. These nodules are formed through a process called hydrogenous deposition, which occurs when minerals precipitate out of seawater and accumulate on the ocean floor. This process is distinct from biogenous deposition, which involves the accumulation of organic material, and terrigenous deposition, which involves the accumulation of land-derived sediments. Therefore, the correct answer is c. hydrogenous.
33.
Calcium carbonate is most likely to dissolve in water with which characteristics?
Correct Answer
C. C) lots of carbon dioxide and cold temperatures
Explanation
Calcium carbonate is most likely to dissolve in water with lots of carbon dioxide and cold temperatures. This is because carbon dioxide reacts with water to form carbonic acid, which can dissolve calcium carbonate. Additionally, lower temperatures increase the solubility of calcium carbonate in water. Therefore, when there is a high concentration of carbon dioxide and the water is cold, calcium carbonate is more likely to dissolve.
34.
High energy environments are most likely to contain which one of the following?
Correct Answer
B. B) large particles such as gravel
Explanation
High energy environments, such as fast-moving rivers or coastal areas with strong waves, are more likely to contain large particles such as gravel. This is because the high energy of the environment makes it difficult for smaller particles to settle and accumulate. In these environments, the force of the water or waves can easily transport and deposit larger particles, resulting in the presence of gravel.
35.
A very important way to increase the settling rate of fine particles in the open ocean is via:
.
Correct Answer
B.
B) fecal pellets
Explanation
Fecal pellets can increase the settling rate of fine particles in the open ocean because they provide a physical structure for the particles to attach to and sink. As marine organisms consume organic matter, they produce fecal pellets that contain both organic material and inorganic particles. These pellets are denser than the surrounding water and can sink to the ocean floor, carrying the fine particles with them. This process helps to remove suspended particles from the water column and promotes sedimentation, ultimately increasing the settling rate of fine particles in the open ocean.
36.
The ________ Ocean is largest
Correct Answer
D. D) Pacific
Explanation
The Pacific Ocean is the largest ocean on Earth. It covers a vast area and has the greatest average depth compared to other oceans. It is also home to the Mariana Trench, the deepest known point in the world. The Pacific Ocean borders many countries and is a major route for international trade and transportation. Its size and importance make it the correct answer in this question.
37.
The ________ marks the transition between the warm surface layer and the deep zone of cold
water in the oceans.
Correct Answer
C. C) thermocline
Explanation
The thermocline is a layer in the ocean that separates the warm surface layer from the colder deep zone. It is characterized by a rapid decrease in temperature with increasing depth. This transition zone is important because it affects the distribution of heat and nutrients in the ocean, as well as the movement of marine organisms. The pycnocline refers to a layer of water where there is a rapid change in density, the halocline refers to a layer of water where there is a rapid change in salinity, and the salinocline refers to a layer of water where there is a rapid change in salt concentration. None of these options accurately describe the transition between warm and cold water in the ocean.
38.
The gently sloping submerged surface extending from the shoreline toward the deep ocean is
termed the ________.
Correct Answer
C. C) continental shelf
Explanation
The gently sloping submerged surface extending from the shoreline toward the deep ocean is termed the continental shelf. This is the area of shallow water that extends from the shoreline to the point where the ocean floor drops off into deeper water. It is typically characterized by gentle slopes and is an important area for marine life and economic activities such as fishing and oil exploration. The continental slope, submarine canyon, and continental rise are all different features that are found beyond the continental shelf.
39.
The continental rise is located ________.
Correct Answer
D. D) between an abyssal plain and continental slope
Explanation
The continental rise is located between an abyssal plain and a continental slope. The continental slope is the steep slope that connects the continental shelf to the abyssal plain, which is a flat and deep part of the ocean floor. The continental rise is a gentle slope that lies at the base of the continental slope and marks the transition between the continental crust and the oceanic crust. It is composed of sediment that has been transported from the continental shelf and slope by gravity and underwater currents.
40.
The ________ Ocean has more extensive abyssal plains than the Pacific Ocean because it has
fewer trenches to trap sediments moving down the continental slope.
Correct Answer
A. A) Arctic
Explanation
The Arctic Ocean has more extensive abyssal plains than the Pacific Ocean because it has fewer trenches to trap sediments moving down the continental slope.
41.
An echo sounder operates by measuring the time required for a ________.
Correct Answer
A. A) sound pulse travels from a ship to the seafloor and back
Explanation
An echo sounder operates by measuring the time required for a sound pulse to travel from a ship to the seafloor and back. This is done by emitting a sound pulse into the water and measuring the time it takes for the pulse to bounce off the seafloor and return to the ship. By knowing the speed of sound in water, the echo sounder can then calculate the distance to the seafloor.
42.
Which of the following contains silica (SiO2)?
Correct Answer
E. E) radiolarians
Explanation
Radiolarians contain silica (SiO2) in their exoskeletons. These marine planktonic organisms construct intricate skeletons made of silica, which are called tests. These tests are composed of SiO2 and are known for their intricate and delicate structures. Radiolarians play a significant role in the ocean ecosystem as they contribute to the silica cycle and are important in the formation of sedimentary rocks.
43.
The major force bringing continental sediments to the open ocean is (are):
.
Correct Answer
E.
E) wind
Explanation
Wind is the major force bringing continental sediments to the open ocean. Wind can transport sediments from land to the ocean through processes such as erosion, deflation, and suspension. These sediments can then be transported by wind currents and deposited in the open ocean. This process is particularly prominent in coastal areas where strong winds and large amounts of sediment are present.
44.
Which one of the following is NOT part of the continental margin?
Correct Answer
C. C) continental trench
Explanation
A continental trench is not part of the continental margin. The continental margin is the submerged outer edge of a continent, and it consists of three main parts: the continental shelf, the continental slope, and the continental rise. The continental trench, on the other hand, is a deep, narrow trench in the ocean floor that is formed by the subduction of one tectonic plate beneath another. It is typically found in areas where one tectonic plate is being forced beneath another, such as along subduction zones.
45.
Sediments which are poorly sorted and made of a variety of minerals could have been deposited
by:
.
.
Correct Answer
C. C) a glacier.
Explanation
Poorly sorted sediments that are made of a variety of minerals are typically associated with glacial deposits. Glaciers have the ability to transport and deposit a wide range of sediment sizes and types as they move and melt. As the glacier moves, it can pick up rocks and minerals of different sizes and compositions, creating a mixture of sediments that are poorly sorted. This is in contrast to other options such as a volcanic eruption, river delta, turbidity currents, or wind, which may deposit sediments that are more sorted or composed of a narrower range of minerals.
46.
Which of the following is NOT true of deep ocean trenches?
Correct Answer
D.
D) they are geologically very stable
Explanation
Deep ocean trenches are not geologically very stable. This is because they are located at subduction zones where tectonic plates collide and one plate is forced beneath another, causing intense geological activity such as earthquakes and volcanic eruptions.
47.
Seamounts ________.
Correct Answer
B. B) are volcanoes that form on the ocean floor
Explanation
Seamounts are underwater mountains that form on the ocean floor due to volcanic activity. They are not submarine canyons, oceanic trenches, or limited to the Pacific Ocean basin. The correct answer, option B, accurately describes seamounts as volcanoes that form on the ocean floor.
48.
How do calcareous oozes form?
Correct Answer
B. B) the particles are precipitated in warm, surface waters and sink to the bottom
Explanation
Calcareous oozes form when particles are precipitated in warm, surface waters and then sink to the bottom. This process occurs in areas with high levels of calcium carbonate, where the warm surface waters provide the necessary conditions for the particles to form and settle. As the particles sink to the bottom, they accumulate and contribute to the formation of calcareous oozes.
49.
________ develop where oceanic lithosphere bends downward and sinks into the mantle.
Correct Answer
B. B) Deep ocean trenches
Explanation
Deep ocean trenches develop where oceanic lithosphere bends downward and sinks into the mantle. This process, known as subduction, occurs when one tectonic plate is forced beneath another plate. As the denser oceanic plate sinks into the mantle, it creates a deep trench on the ocean floor. These trenches are the deepest parts of the ocean and are often associated with intense seismic activity and volcanic eruptions.
50.
Which ocean has the greatest average depth?
Correct Answer
C. C) Pacific
Explanation
The Pacific Ocean has the greatest average depth compared to the other options. This is because the Pacific Ocean is the largest and deepest ocean in the world, covering a vast area and containing the Mariana Trench, which is the deepest part of any ocean. The Indian Ocean, Atlantic Ocean, and Arctic Ocean have lesser average depths in comparison.