1. OCEANS: Physical Features CGF3M Nov. 19, 2013

2. Beneath the oceans lie rugged mountains, active volcanoes, vast plateaus, and bottomless trenches The deepest point is 36,000 ft. in the Mariana Trench in the Western Pacific- VIDEOVIDEO

3. Sea Floor Features

4. Continental shelves (F) - around most continents. Gently sloping, shallow seas Continental slope (A) - lead down to the deepest part of the ocean Abyss (C) - The bottom of the ocean. Where ocean ridges form Ocean trenches (G) - deepest part of the ocean Seamounts (B) – underwater mountains Ridge (D) - Where the sea floor spreads (Divergent plate boundary) Volcanic Island (E) – A seamount that rises out of the ocean. Usually active.

5. How do we Know? Oceanographers have spent much time mapping the ocean floor- BUT it is still largely unknown. Early methods involved dropping a long piece of weighted rope down and measuring how much line was out when the weight reached the bottom Now, echo (SONAR) sounders are used- send out a pulse of sound energy, measure the time it takes to reflect back

6. SONAR has shown us that ocean ridges form a great mountain range, almost 64 000 km long, that weaves its way through all the major oceans. It is the largest land feature on Earth.

7. OCEAN EXPLORATION The next frontier? TED TALK TED TALK Why should we explore our oceans? Read the article “Looking for Life at the Bottom of the Sea”, answer the questions.