Warm Up 2/6/09 1. 1. What technology do scientists use to measure ocean depth? a. sonarc. rope b. submersibled. laser 2. 2. Differences in ocean-surface.

Warm Up 2/6/09Warm Up 2/6/09

1. What technology do scientists use to measure ocean depth?a. sonar c. ropeb. submersible d. laser

2. Differences in ocean-surface height can be measured by ____.a. satellites c. submersiblesb. sonar d. none of the above

3. Approximately how much of Earth’s surface is covered by land?a. 60 percent c. 30 percentb. 70 percent d. 50 percent

Answers: 1) a. 2) a. 3) c.

Ocean Floor Ocean Floor FeaturesFeatures

Chapter 14, Section 2Chapter 14, Section 2

Profile of North Atlantic Profile of North Atlantic OceanOcean

Continental MarginsContinental Margins Continental Margin – the zone of

transition between a continent and the adjacent ocean basin floor

In the Atlantic Ocean, thick layers of undisturbed sediment cover the continental margin. This region has very little volcanic or earthquake activity

In the Pacific Ocean, oceanic crust is plunging beneath continental crust. This force results in a narrow continental margin that experiences both volcanic activity and earthquakes

Passive Continental Passive Continental MarginMargin

Continental Shelves, Slopes, Continental Shelves, Slopes, and Risesand Rises

Continental Shelf – the gently sloping submerged surface extending from the shoreline

Continental shelves contain important mineral deposits, large reservoirs of oil and natural gas, and huge sand and gravel deposits

Continental Slope – the seaward edge of the continental shelf

The continental slope is a relatively narrow feature along the continental shelf

Submarine Canyon – deep, steep-sided valleys cut into the continental slope

Turbidity Currents – occasional movements of dense, sediment-rich water down the continental slope

Turbidity currents are known to be an important factor in sediment transfer in the ocean

Continental Rise – a gradual incline which merges with the steep continental margin, occurs in regions where trenches do not exist

Continental Shelves, Slopes, Continental Shelves, Slopes, and Rises Continuedand Rises Continued

Submarine CanyonsSubmarine Canyons

Concept CheckConcept Check

Compare and contrast the continental slope and continental rise.

Continental slope marks the steep boundary between continental crust and oceanic crust. The continental rise occurs at the end of the continental slope and has a more gradual incline.

Ocean Basin FloorOcean Basin Floor Ocean Basin Floor – area between the

continental margin and the mid-ocean ridge Deep-ocean trenches are long, narrow creases

in the ocean floor that form the deepest parts of the ocean

Trenches form at sites of plate convergence where one moving plate descends beneath another and plunges back into the mantle

Abyssal Plains – deep, extremely flat features and are the most level places on Earth

The sediments that make up abyssal plains are carried there by turbidity currents or deposited as a result of suspended sediments settling

Ocean Basin Floor Ocean Basin Floor ContinuedContinued

Seamounts – the submerged volcanic peaks which dot the ocean floor

Once underwater volcanoes reach the surface, they form islands

After millions of years, the tops are eroded away and the once active islands sink back into the ocean, forming guyots

Abyssal PlainAbyssal Plain

Concept CheckConcept Check

What are abyssal plains? Deep, extremely flat regions of the

ocean floor.

Mid-Ocean RidgesMid-Ocean Ridges Mid-Ocean Ridge – found near the center

of most ocean basins; an interconnected system of underwater mountains that have developed on newly formed ocean crust

Seafloor Spreading – occurs at divergent plate boundaries where two lithospheric plates are moving apart

New ocean floor is formed at mid-ocean ridges as magma rises between the diverging plates and cools

Hydrothermal vents form along mid-ocean ridges and are zones where mineral-rich water escapes through cracks in oceanic crust into the surrounding cooler water

Profile of North Atlantic Profile of North Atlantic OceanOcean

Assignment (Due 2/13)Assignment (Due 2/13)

Read Chapter 14 (pg. 394-413) Do Chapter 14 Assessment #1-33 (pg. 417-418)

Cool DownCool Down What is formed at mid-ocean ridges? New ocean floor Compare and contrast seamounts and

guyots. A seamount is an underwater volcano that

has not reached the surface yet. A guyot is a volcanic island that has been eroded and sunk back under the water’s surface.

What is one thing new that you learned today? Explain what it is.