What is the hypothesis of seafloor spreading?
seafloor spreading, theory that oceanic crust forms along submarine mountain zones, known collectively as the mid-ocean ridge system, and spreads out laterally away from them.
What is the major evidence that seafloor spreading?
Several types of evidence supported Hess’s theory of sea-floor spreading: eruptions of molten material, magnetic stripes in the rock of the ocean floor, and the ages of the rocks themselves.
How did Harry Hess discover seafloor spreading?
Hess discovered that the oceans were shallower in the middle and identified the presence of Mid Ocean Ridges, raised above the surrounding generally flat sea floor (abyssal plain) by as much as 1.5 km. This created new seafloor which then spread away from the ridge in both directions.
How does the hypothesis of seafloor spreading help explain why continents are able to move?
Significance. Seafloor spreading helps explain continental drift in the theory of plate tectonics. When oceanic plates diverge, tensional stress causes fractures to occur in the lithosphere. Plates that are not subducting are driven by gravity sliding off the elevated mid-ocean ridges a process called ridge push.
What evidence helped give strong support for the hypothesis of seafloor spreading at mid-ocean ridges?
This hypothesis was supported by several lines of evidence: (1) at or near the crest of the ridge, the rocks are very young, and they become progressively older away from the ridge crest; (2) the youngest rocks at the ridge crest always have present-day (normal) polarity; and (3) stripes of rock parallel to the ridge …
What is the major evidence that seafloor spreading creates new lithosphere?
The record of magnetic reversals is carried away from each side of the spreading center of a mid-ocean ridge, showing that the molten rock is creating new lithosphere.
What supports Hess’s theory of seafloor spreading?
Magma flows to the opening and then cools to form new sea floor. Sea floor continues to spread apart as new crust is added. Evidence supported Hess’s theory of sea-floor spreading: eruptions of molten material, magnetic stripes in the rock of the ocean floor, and the ages of the rocks themselves.
What observation first led to the theory of seafloor spreading?
Hess’s discovery on the warmer temperature near the mid-Atlantic ridge when he began the ocean mapping, led to his evidence about the molten material underneath the ocean. The condition on the mid-oceanic ridge was substantially different from other surfaces away from the region because of the warmer temperature.
How does Harry Hess theory on how the seafloor spreads support Alfred Wegener’s continental drift theory?
Supporting Wegener’s theory of continental drift, Hess explained how the once-joined continents had separated into the seven that exist today. Hess also theorized that because the continental crust was lighter, it didn’t sink back into the deep earth at trenches as did the oceanic crust.
What evidence helped support the theory of seafloor spreading?
Evidence for Sea-Floor Spreading. Several types of evidence supported Hess’s theory of sea-floor spreading: eruptions of molten material, magnetic stripes in the rock of the ocean floor, and the ages of the rocks themselves. This evidence led scientists to look again at Wegener’s hypothesis of continental drift.
How do scientists prove the seafloor is spreading?
Evidence of Sea Floor Spreading Molten material. Hess’s discovery on the warmer temperature near the mid-Atlantic ridge when he began the ocean mapping, led to his evidence about the molten material underneath the ocean. Seafloor drill. The seafloor drilling system led to the evidence that supports the seafloor-spreading hypothesis. Radiometric age dating and fossil ages.
What is the theory of seafloor spreading?
The Theory of Seafloor Spreading. Seafloor spreading is a geologic process where there is a gradual addition of new oceanic crust in the ocean floor through a volcanic activity while moving the older rocks away from the mid-oceanic ridge.
What is Harry Hess’s theory of seafloor spreading?
This theory later became known as ‘Sea Floor Spreading’. Hess envisaged that oceans grew from their centres, with molten material (basalt) oozing up from the Earth’s mantle along the mid ocean ridges. This created new seafloor which then spread away from the ridge in both directions.