OCEANS:Physical Features

CGF3M Nov. 19, 2013

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- VIDEO

Sea Floor Features

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.

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

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.

OCEAN EXPLORATIONThe next frontier?

TED TALK

Why should we explore our oceans?

Read the article“Looking for Lifeat the Bottom ofthe Sea”, answerthe questions.