Features of the Ocean Floor Ms. Bridgeland 6 th Grade
Features of the Ocean Floor How do you imagine the ocean floor? It may be a surprise but…..
4 main features of the Ocean Floor 1) continental shelf –shallow area of ocean floor 2) continental slope-steep edge of the continental shelf 3) abyssal plain-smooth, flat region of the ocean floor 4) mid-ocean range-range of mountains that passes through all of Earth’s oceans
Features of the Ocean Floor
Abyssal Plain
1) Continental Shelf *A gently sloping, shallow area of the ocean floor that extends outward from the edge of a continent *Extends about 130 meters
Continental Slope The steep edge of the continental shelf Drops down at a sharp angle Marks the true edge of a continent, where the rock that makes up the continent stops and the rock of the ocean floor begins
Abyssal Plain The smooth, nearly flat region of the ocean floor Has thick layers of sediment, formed by the remains of dead organisms from the surface Remember: FLAT REGION
Abyssal Plain
Mid-ocean ridge A continuous range of mountains that winds around the Earth Passes through all of Earth’s oceans Nearly 80,000 kilometers long Longest mountain range on earth Consists of many peaks along both sides of a central valley
Mid-Ocean Ridge
Volcanic Islands When volcanoes on the ocean floor erupt, they can create mountains whose peaks break the surface of the ocean. As the lava cools, islands form
Volcanic Islands
Look for a Volcanic Island
Seamounts Mountains whose peaks do not break the surface of the ocean water
Seamount
Trenches A dark gash in the ocean floor A canyon A hole so deep that you cannot see the bottom
Look for the Trench
What do PLATES have to do with the ocean floor? PLATE MOVEMENTS HAVE SHAPED MANY OF THE MOST DRAMATIC FEATURES OF THE EARTH, BOTH ON LAND AND UNDER THE OCEAN
Seafloor Spreading Plates “diverge” or move apart Along the ridge, magma (lava) squeezes up through the cracks, and as it hardens, it adds a new strip of rock to the ocean floor
Divergent Plates
Seafloor Spreading
As magma (lava) squeezes up through cracks between diverging plates, magma hardens along the ride. The hardened magma adds a new strip of rock to the ocean floor This is called “seafloor spreading” because it produces new ocean floor
Seafloor Spreading
Converging Plates When plates are pushed together, one plate sinks under the other In a TRENCH, old ocean plates converge and sink
TRENCHES –convergent plates
Converging Plates