Ch 10

True or false: The youngest oceanic crust is located farthest from the mid-ocean ridge on the map shown. O True O False

False Reason: The oceanic crust gets progressively older farther away from the mid-ocean ridge.

Which of the following can be distracted from drill cores to determine the numeric age of the age of the sediment on the sea floor?

Fossils Volcanic materials

Select all that apply Which of the following can be extracted from drill cores to determine the numeric age of the sediment on the seafloor? 0 Oxygen isotopes 0 Fossils 0 Volcanic minerals

Fossils Volcanic minerals

Click and drag on elements in order Order the location of seafloor regions by elevation with the highest elevation at the top and the lowest elevation at the bottom Abyssal plain Mid-ocean ridge Oceanic trench

1. Highest -Mid-ocean ridge 2. Abyssal plain 3. Lowest- Oceanic trench

Match the time period with the correct event that shaped the Gulf of Mexico and the Caribbean

Jurassic Period ( ~ 200 to 145Ma) North America rifted apart from Africa and South America , as a result of seafloor spreading .

Hawaiian islands are a ___ chain

Linear

Multiple choice: Island arcs such as those in Indonesia are likely to have _______ volcanoes. O effusive shield O no O dangerous composite

Dangerous composite

The _______Plateau and the _______Plateau are oceanic plateaus that formed over 100 million years ago O Ontong Java; Kerguelen O Tahitian; Galápagos O Tristan da Cunha; Hawaiian

Ontong Java; Kerguelen

Multiple Choice Question: Where are the areas with the shallowest seafloor depths? O (T) trenches O (P) passive continental margins O (R) mid-ocean ridges

(P) passive continental margins

Multiple choice: The igneous rock type you are least likely to find on oceanic islands would be________ in composition. © Ovmafic O intermediate O felsic

FELSIC is Least

Ontong Java is the largest oceanic_____ on earth

Plateau

Multiple choice: How are satellites utilized to creates maps of the seafloor ?

Radar bounces off the sea surface , which has variations in it due to the gravitational forces of the underlying topography .

How are satellites utilized to creates maps of the seafloor? O Radar bounces off the sea surface, which has variations in it due to the gravi- tational forces of the underlying topography. O Lasers measure the changes in water density from the surface to the seafloor, which reflects the types of seafloor sediments. O Sonar penetrates the water column, and the sound waves bounce off the seafloor.

Radar bounces off the sea surface, which has variations in it due to the gravi- tational forces of the underlying topography.

Multiple Select Question Select all that apply Which creatures belong to the community of organisms that live at hydrothermal vents? O Giant clams O Silver-gray sharks O Red tube worms O White crabs

Red tube worms Giant clams White crabs

Fill in the blank

Relative numeric

Ordering Question Click and drag on elements in order Order the processes that formed Monterey Canyon along its length from onshore to the deep sea , with the first event at the top and the last event at the bottom.

1. The canyon was cut below sea level 2.canyon was cut by turbidity currents 3. Sediment deposits built up a submarine fan

Oldest oceanic crust is

180 million

How old is the oldest oceanic crust? O 4.56 billion years O 2 million years O 180 million O3 billion years

180 million years

Click and drag on elements in order Order the steps in the formation of a seamount from the first event at the top to the last event at the bottom.

1st a conical basaltic volcano forms an island. The volcanic mountain cools and subsides. The top of the volcano is flattened by wave erosion and continues to subside. last-The flat-topped volcano is buried by sediment.

Select all that apply Using the map determine where the sediment cover is the thickest on the seafloor. O Near river mouths O Along the continental margins O Near young ocean crust O At the mid-ocean ridges

Along Continental margins Near River mouths

Select all that apply Which of the following describe the formation of an island are? O An island arc most commonly forms at a hot spot on the ocean floor. O An island arc forms in association with an oceanic trench. O The magma that creates the islands is formed due to the release of water in the subducted plate. O The subducted oceanic plate melts to form the magma used to create the is- land arc.

An island arc forms in association with an oceanic trench. The magma that creates the islands is formed due to the release of water in the subducted plate.

.Trench rollback occurs as subduction continues and the trench rolls ___ the island arc. O toward O away from

Away from

What is the source of energy for giant tube worms and clams that live at hydrothermal vents? O Plants that grow on the seafloor O Bacteria that break down H,S O Sunlight

Bacteria that break down H,S

What is the source of energy for giant tube worms and clams that live at hydrothermal O Plants that grow on the seafloor O Bacteria that break down H2S O Sunlight

Bacteria that break down H2S

What rock type forms oceanic plateaus? O Granite O Basalt O Rhyolite

Basalt

Click and drag on elements in order Put the processes that occur when oceanic plates spread apart at the mid-ocean ridge in order, from the first event at the top to the last event at the bottom. ® Instructions Oceanic crust has a smooth surface covered by layered sediment. Blocks of oceanic crust are downdropped in normal faults Sediment settles onto new basalt. Oceanic crust has a smooth surface covered by layered sediment.

Basaltic lava erupts from the rift. Blocks of oceanic crust are downdropped in normal faults. Sediment settles onto new basalt. Oceanic crust has a smooth surface covered by layered sediment.

Magma that erupts at mid-ocean ridges forms pillow____ pushed away from the ridge crest and covered with clay-rich_____

Basalts Materials, sediment, or sediments

Multiple Choice Question The hot water emitted by______at mid-ocean ridges is actually recycled seawater that flows into the subsurface and is heated by a magma source.

Black smokers

Fill in blank A submarine volcano is created when ocean floor moves over a hot spot. When the volcano rises above sea level, a(n)__________is formed that eventually will be eroded and subside under the sea.

Blank 1: seamount or guyot

The CCD or______compensation depth, is the depth at which calcite disappears in the

Carbonate

Magmas that are intermediate in composition form island arcs with explosive _______ volcanoes made of andesite.

Composite

Fill in the Blank Question Geologists can learn about past environments and climates by collecting cylinder shaped drill _________from the seafloor.

Core

Hot water, metals, and sulfur discharge from __________ vents aka: as black smokers) at mid-ocean ridges.

Hydrothermal

The volcanic rocks on oceanic islands are______ to intermediate in composition.

Mafic

Multiple Choice Question The direct source of heat for the water emitted by black smokers at mid-ocean ridges comes from O magma O an unknown source O radioactive decay O friction

Magma

Oceanic plateaus form from basaltic volcanism originating from O trenches O mid-ocean ridges O mantle plumes

Mantle plumes

What was the first methodology used to gain an understanding of the undersea geology of the Gulf of Mexico and the Caribbean, in order to reconstruct the region's history?

Mapping of geology on land

Matching The spreading ridge with characteristic type

Mid-Atlantic Ridge—————————Well-defined central rift valley East Pacific Rise————Broad and lacking a central rift

Fill in the Blank Question: The enormous submarine canyon located off the coast of central California in _______________Bay is very well studied for both its geologic and biologic features , as well as being a national marine sanctuary .

Monterey

Baseball-sized spheres that precipitate out of seawater and fall to the seafloor are called manganese_________

Nodules

The red dots that coincide with volcanically active island chains, shown on the map, are_______called O island arcs O mid-ocean ridges O abyssal plains O hot spots

O hot spots

There is great debate, however, about which areas are really hot spots and how hot spots form.

One hot spot on which nearly all geologists agree is Iceland, which is barely visible on this globe.

4 methods used to explore topography and rocks of the sea floor

Satellites, submarines and submersibles, drilling, and sonar

Satellites usually collect data regarding______ properties

Sea surface

Satellites collect data about sea surface height; we use this information to create maps of ______.

Seafloor topography

Match the seafloor feature with its description. Feature: Seamount Abyssal plain Oceanic trench Description: Deepest part of the ocean Deep seafloor with smooth topography Isolated mountain

Seamount —————-isolated mountai Abyssal plain————Deep seafloor with smooth topography Oceanic trench———Deepest part of the ocean

Match the seafloor feature with the description of its formation.

Seamount—-Submarine volcanic eruptions Trench—-Downwarping of an oceanic plate as it plunges beneath another plate Mid-ocean ridge—-Rifting at divergent plate boundaries

Manganese nodules form on the deep sea floor as other manganese and metals precipitate from ____

Seawater

Multiple choice Rocks beneath the sealer can be imaged with sound waves using a method called _________profiling

Seismic reflection

What method produces images of the materials beneath the seafloor using sound waves?

Seismic-reflection profiling

Select all that apply Why does a well-defined, deep rift form at some spreading ridges, such as the one featured in the image? - The spreading rate is fast. - A large magma source lies underneath. - Large, normal faults form. -The spreading rate is slow.

Slower spreading rate Large norma faults

Island arcs form in association with what type of tectonic setting? O Subduction zones O Continental rift zones O Convergent zones

Subduction zones

Select all that apply Why does the seafloor decrease in elevation with distance from the mid-ocean ridge? -The seafloor cools down. - The seafloor becomes younger. -The seafloor heats up. -The seafloor becomes denser.

The seafloor cools down. The seafloor becomes denser.

Select all that apply: Why does the seafloor decrease in elevation with distance from the mid-ocean ridge? O The seafloor cools down. O The seafloor heats up. O The seafloor becomes denser. OThe seafloor becomes younger.

The seafloor cools down. The seafloor becomes denser.

Multiple Select Question Select all that opply What do the areas shown in red on the map have in common O The regional volcanoes are not considered dangerous O They are all island arce, O They are unrelated to plate tectonics. O They formed adjacent to deep trenches.

They are all island arcs. They formed adjacent to deep trenches.

Multiple Choice Question Deep-sea sediments lack carbonate minerals because______ O all the carbonates here are used by organisms O carbonates are not formed in seawater O they are located beneath the CCD

They are located beneath the CCD

Multiple Choice Question: Why are island arcs curved? O They form next to trenches on a spherical Earth. O Gravity pulls the plates toward the poles. O They are small segments offset by faults.

They form next to trenches on a spherical Earth.

Multiple select question Select all that apply Which of the following statements describe black smokers? O They form sulfide-rich chimneys. OThey form from magma. O They form along mid-ocean ridges. OThey form mineral deposits rich in copper and zinc.

They form sulfide-rich chimneys. They form along mid-ocean ridges. They form mineral deposits rich in copper and zine.

What do the island chains of Hawaii, Tahiti, and Tristan da Cunha have in common? O They are part of an oceanic plateau. O They are part of island arcs. © They formed from hot spots.

They formed from hot spots

True or False Question: Most oceanic measurements made from satellites are of ocean surface properties , rather than deep - ocean properties .

True

True or false: There is virtually no sediment cover on the youngest crust at the mid-ocean ridges. O True O False

True: Reason: The sediment cover on ocean crust gets progressively thicker away from mid-ocean ridges.

The area behind an island arc that develops a spreading center and rifts is a(n) _______ O back-arc basin O abyssal plain O trench O passive margin

back-arc basin

Hawaii is the most famous island chains

formed by movement of a plate over a hot spot

The Sea of Japan formed as a deep basin between Asia and Japan because____. O of trench subduction O of back-arc seafloor spreading O it is part of a continental platform

of back-arc seafloor spreading

On the map shown, R has the youngest oceanic crust because it is at a ______.

spreading center

Hot spots form linear island chains because_______. O the plate moves relative to the underlying hot spot O they occur along the mid-ocean ridges O they are aligned with trenches formed by subduction

the plate moves relative to the underlying hot spot

Multiple choice: Hot spots, indicated by the red dots on the map, coincide with O abyssal plains O volcanically active island chains O mid-ocean ridges

volcanically active island chains