Ocean Floor Chapter 23

How much of the earth is covered by water? About 71%

Name the five oceans on earth? The ____________ Ocean The ___________ Ocean The ____________ Ocean

Southern or

What’s under all that water???

The earths crust of course! Composed of the igneous rock (basalt)

Oceanic Crust is made of one type of rock: igneous basalt 7 km (5 miles ) thin Composed of dark, igneous rock –Basalt (black, ocean basin) –3.0 g/ml density –180 million years young (or less)

What does the ocean crust look like ? touring the ocean floor How do we know what is under the ocean? (Think back to how Wegener’s Hypothesis was able to be proven…WWII…) Write and define the following ocean floor features (start reading on page 514) Mid Ocean Ridge Rift Valley Hydrothermal Vents Seamount Island Arc Abyssal Plain Continental Shelf Continental Slope Continental Rise Submarine Canyon SONAR

The same as the continental crust: it has mountains, canyons, hills, valleys ridges, plains …

Ocean ridges rise up above the ocean floor and contains many faults and fractures.

Rift Valley in a Mid Ocean Ridge

At mid-ocean ridges volcanic vents spew smoke and hot gases, and heat the surrounding water where a few types of marine life can survive and flourish. Hydro-thermal vents nBVe1vsA&index=3&feature=plcp

Thousands of seamounts dot the ocean floor. Sea mounts: under the sea volcanic mountains Smaller hills punctuate the abyssal plains are most common in the Atlantic Ocean

The Hawaiian Island arc are part of a long chain of seamounts that stick out above the water in the Pacific Ocean

Abyssal plains are large flat basin with little of no slope. The rugged ocean floor is filled-in and smoothed by layers and layers of sediment.

Just as a heavy snowfall covers all the features of the street, Sediment covers all the rugged features on the ocean floor smoothing it flat

Abyssal plains Are extremely level. They are the flattest places on earth! cover about one-half of the deep-ocean floor. The flatness of these plains is the result of the accumulation of a blanket of sediments, up to 5 kilometers thick! ( which overlies the basaltic rocks of the oceanic crust.)

Continental Margin The Continental Margin is the underwater part of the continental crust. Continental Margin

Where does the continent stop and the ocean floor begin?? Pg 514 The continental shelf and continental slope are attached to the continent, Where as the sediments of the continental rise sit on the ocean floor. Continental Ocean

23.2 Passive and Active Continental Margins

Profile of a PASSIVE continental margin: they are not located at a plate boundary

The shallow, continental shelf can extend for many miles

Passive, peaceful beaches

U.S. East coast has a very wide PASSIVE continental shelf On your map, find and label passive continental margins in pink.

Gulf of Mexico has passive margins consisting of MILES of continental shelf and shallow seas

Continental shelf East coast of S. America Australia

Often there is a steep, deep drop off at the edge of the continental shelf to the ocean floor called the continental slope.

Where are the sandy beaches and shallow water? Instead we see steep, rocky slopes

The U.S. Pacific coast is an ACTIVE continental margin that has steep rocky mountains with little beaches.

Mountains and volcanoes are found along ACTIVE continental margins where the dense ocean crust is forced under the continental crust. At CONVERGENT (coming together) boundaries

The Andes Mountains in South America are the worlds longest mountain range. It is an active continental margin. The Peru-Chili TRENCH runs along the western edge of the continent

Active continental margins have steep slopes and deep trenches Steep continental slope Deep trench Coastal mountains Abyssal plain

Deep trenches are located around the Pacific ocean

It's the deepest spot in the world! "Grand Canyon of the Pacific” It’s 1,580 miles long and 43 miles wide. It is 11,033 meters, 36,201 feet or 6.86 miles deep (below sea level) The pressure at the deepest part of the Mariana Trench is over 8 tons per square inch. (compared to 14 pounds/sq. in. on the surface). If Mount Everest, the highest mountain on Earth, were placed in the trench it would be covered by over one mile of water! The Mariana Trench

How deep is it? Mariana Trench Is the deepest Place on the Earth! Mt. Everest could fit in the Mariana Trench and still not stick out above the water! 29,000 ft 36,200 ft (6.8 miles!)

The west coast of the U.S. has steep, sloping canyons

Monterey, California A submarine canyon Page

Erosion of soil/sediment (due to water) forms canyons

A steep canyon cuts into the narrow continental shelf and extend out onto the ocean basin.

Monterey Bay, California Monterey Canyon at over two miles is twice as deep as Arizona’s Grand Canyon.

Match that ocean feature! 1.Under sea volcanoes. 2.Flattest part of the ocean. 3.Deepest places in the ocean. 4.Shallow water at edge of a continent. 5.Margin where earthquakes and volcanoes occur. 6.Where the magma pushes up. 7.43,000 miles long! 8.Where the continent ends. a.Active margin b.Passive margin c.Ridge d.Rift valley e.Trench f.Seamount g.Abyssal plain h.Continental rise i.Continental shelf j.Continental slope

Name that feature! __ __ E C D H A F B G

Bell work 1. Where is new ocean floor being created? 2. Where is ocean floor being destroyed (recycled)? 3. Where is new land being added to continents? a. Abyssal plain b. Trenches c. Continental slope d. Mid-ocean ridges d. ridges b. trenches c. Continental slope

Video Quiz on ocean features

Bell work What percent of salt does the ocean contain? ___________% salt What body of water is the saltiest? What percent? ___________%