Chapter Chapter 19 19

Section 2 Section 2 Review Review

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1. Describe the three 1. Describe the three main main sections of the sections of the

continental continental margins.margins.

• The continental shelf is the The continental shelf is the submerged part of the continent. submerged part of the continent.

• The continental slope is the The continental slope is the steep, seaward edge of the steep, seaward edge of the shelf. shelf.

• The continental rise is a raise The continental rise is a raise wedge of sediment at the bottom wedge of sediment at the bottom of the slope.of the slope.

Continental MarginContinental Margin

2. 2. Describe where the Describe where the boundary between the ocean boundary between the ocean crust and the crust and the continental continental crust is located.crust is located.

• The boundary is generally The boundary is generally offshore at the base of the offshore at the base of the continental slope.continental slope.

Continental SlopeContinental Slope

3. Explain how turbidity 3. Explain how turbidity currents are currents are

related to related to submarine canyons.submarine canyons.

• Submarine canyons may form Submarine canyons may form where large amounts of where large amounts of sediment tumble down a slope sediment tumble down a slope as part of a turbidity current.as part of a turbidity current.

Turbidity CurrentsTurbidity Currents

4. List four main 4. List four main features features of the deep- of the deep-ocean ocean basins, basins, and describe one and describe one characteristic of each characteristic of each

feature. feature.

• Trenches: very deep, formed by Trenches: very deep, formed by subductionsubduction

• Abyssal plains: vast, flat areas Abyssal plains: vast, flat areas more than 4 km. deep and more than 4 km. deep and covered with a fine sedimentcovered with a fine sediment

4. (Continued)4. (Continued)

•Mid-ocean ridges: form Mid-ocean ridges: form where plates move apart and where plates move apart and have a narrow rift have a narrow rift

•Seamounts: submerged Seamounts: submerged volcanoes that may rise volcanoes that may rise above the ocean to form above the ocean to form volcanic islandsvolcanic islands

Seafloor FeaturesSeafloor Features

5. Compare seamounts, 5. Compare seamounts, guyots, and guyots, and

atolls.atolls.• A seamount is an underwater A seamount is an underwater

volcanic mountain.volcanic mountain.

• Guyots and atolls form from Guyots and atolls form from islands. When an island sinks islands. When an island sinks and the top erodes flat you get a and the top erodes flat you get a guyot. Before the island sinks guyot. Before the island sinks completely an atoll may form completely an atoll may form around the sinking volcano in around the sinking volcano in the shallow water.the shallow water.

Seafloor FeaturesSeafloor Features

Formation of an Formation of an AtollAtoll

An atollAn atoll

6.6. Explain the difference between Explain the difference between the meanings of the terms the meanings of the terms continental margin, continental continental margin, continental shelf, continental slope, and shelf, continental slope, and continental rise.continental rise.

• The continental margin is the The continental margin is the name for all parts combined; name for all parts combined;

• the continental shelf, continental the continental shelf, continental slope, and the continental rise.slope, and the continental rise.

Continental MarginContinental Margin

Image: Continental margin –Image: Continental margin –California coastCalifornia coast

TheThe End? End?