The Sea Floor - Mediapolis Community School

The Sea Floor - Mediapolis Community School

The Sea Floor CH 2 pg 19 Geosphere Geological processes influenced terrestrial and

marine environments Earth is broken into layers.. Crust Mantle Core (inner/outer)

Geological Layers of Earth Crust - 1% Earths mass thinnest layer Continental Granite, less dense, floats on top oceanic Oceanic Basalt, dense, thinner than continental

Lithosphere is part of the upper mantle Mantle - layers beneath the crust Lithosphere (broken into plates; tectonic) Asthenosphere (plates float on top)

Silly putty Heated and becomes less dense so material rises then as it cools material sinks creating circulating currents called convection currents Causes plates to move

Geological Layers of Earth Core - innermost layer Outer core Dense liquid Moves counter clockwise thought to

create magnetic field Inner core Solid due to pressure Iron and Nickel Oceans

71% of Planet Regulate climate and atmosphere Geography of the Ocean Basin 2/3 of the earths land area in the Northern Hemisphere

The Southern Hemisphere 80% of the ocean Five Large Basins Pacific Ocean deepest (approx. 14000 ft) and the largest

narrowing Atlantic Ocean Slowly getting bigger Indian Ocean

Arctic Ocean Southern Ocean Difference between ocean and sea? The Origin and Structure of the Ocean Basins (1912) Continental Drift Theory

All the continents had once been joined in a single supercontinent called Pangea Approx 180 m.y.a. (1950s and 1960s) Plate tectonics Plates did drift lead to the discovery of the

Mid-Ocean Ridge Evidence

Pieces of a puzzle Matching sequences of rock & mountains Distribution of organisms Magnetic fields

Igneous rock Magnetite and iron The Mid-Ocean Ridge System of volcanic mounts that encircles the globe Largest geological feature on earth

Submarine mountains can break the surface of the water to form islands (ex. Iceland) Eastern Pacific Ridge (Subduction) Subduction vs Divergent

Creation of the Sea Floor Pieces of oceanic crust separate mid-ocean ridges by creating cracks called rifts. Rifts release the pressure on the mantle Reduced pressure allows hot mantle material to rise up through the rift.

The magma pushes up around the rift It cools as it enters the surrounding water Creating a ridge Atlantic Ocean getting larger (Divergent) Creating New Seafloor

Repeating process makes the seafloor move away from the mid-ocean ridge Mid-ocean ridge form the edges of continents As the plates move the continent is carried with it (2.5 ~ 7cm/year)

Seafloor younger closest to the ridge Aleutian Islands pg 28 Trenches curve due to Earths spherical shape Volcanic islands follow trenches

Island Arcs Hot Spots pg 36 Hawaiian Islands (plate movement) vs Aleutian Islands (subduction) Hawaiian Islands are formed as a result of

the movement of plate over a hot spot Magma oozes from the thinner oceanic crust Cools and creates a seamount Eventually breaks the surface Southern islands are younger

Continental Volcanoes pg23 Collision between ocean and continental plates result in volcanoes Continent vs Continent Himilayas & Great Smokey Mountains

Transform Boundaries Shear boundary Plates that slide past each other Friction prevents the plates from sliding smoothly They lock up and stress builds up until the

plates break free Cause an earthquake San Andres Fault (pg 29) The Ocean Floor Sea floor is dominated by plate tectonics

Sea floor is divided into two main regions; Continental margin Deep-sea floor Continental Margins Region between the continental crust and

oceanic crust Continental Shelf Continental Slope Continental Rise Continental Shelf

Shallow makes up 8% of the oceans surface area 400-600 ft deep Rich in life ends at the shelf break Continental crust

covered in sea water Continental Slope Exact edge of the continent Starts at the shelf break Descends to the deep-sea

Continental Rise Sediment forms at the base of the continental slope Deep-Ocean Basins

10,000 16,500 ft deep abyssal plain Mariana Trench West Pacific Depth of 36,163ft (7 miles)

Hydrothermal Vents

Fractures in crust water seeps down Heated water pushes its way up Creating a hydrothermal vent Temp ranging from (50 550o)

The water contains minerals and sulfides As the water cools the minerals solidify and deposit themselves around the vents creating chimneys, commonly called black smokers.

Tallest chimney so far rises 200 ft above sea floor

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