Download Seafloor Spreading Notes Harry Hess He was a geology Professor

Seafloor Spreading Notes
Harry Hess
 He was a geology Professor at Princeton
 He was also a Navy Captain in World War 2
 Used the SONAR on his ship, which was meant for finding enemy
submarines, to map the Ocean Floor
 He discovered the Pacific Ocean floor had Mt. Ranges and
Trenches
Seafloor Spreading Theory
 After extensive research, Hess believed that the oceans spread
from their centers at Mid Ocean Ridges
 Magma/Lava oozed up from the Earth’s mantle along the mid
ocean ridges into the ocean.
 This created new Seafloor which then spread away from the
ridge in both directions.
 As spreading continued, the older ocean floor cooled and sank
Why Isn’t Earth Growing ?
 While Hess believed that as the Ocean floor was growing from the
middle
 He also believed it was being destroyed and recycled near the
Continents at Deep Ocean Trenches
 This process is called Subduction
Mid Atlantic Ridge
 Worlds largest Mid Ocean Ridge
 Believed to be the force Wegener was looking for to explain how
continents drifted apart
 Stretches about 12,000 miles from the Tip of Africa to the Arctic
Ocean
 Can reach nearly 1000 miles wide
 Over 1 mile high in certain spots
Mariana Trench
 The Mariana Trench lies near the Philippines in the Pacific Ocean
 It is a crescent-shaped scar in the Earth’s crust that measures
more than 1500 miles long and 43 miles wide
 The distance between the surface of the ocean and the trench’s
deepest point is nearly 8 miles
 If Mt. Everest were dropped into the Mariana Trench, its peak
would still be more than a mile underwater.