Quick Answer: What Was Harry Hess’S Theory Of Seafloor Spreading?

What is the theory 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.


At what depth do opposing continental coastlines have the best jig saw fit?

The best fit is obtained if the coastlines are matched at a depth of 1,000 metres below current sea level.

What is the evidence that supports the theory of plate tectonics?

Evidence from fossils, glaciers, and complementary coastlines helps reveal how the plates once fit together. Fossils tell us when and where plants and animals once existed. … This distribution of fossils led to theories that the southern continents were once joined in a supercontinent called Gondwana.

What is the average speed of seafloor spreading?

approximately 5 centimeters a yearThe average speed of seafloor spreading is approximately 5 centimeters a year. This growth rate can be compared to the growth rate of human fingernails (Krupicka). The global ridge system consists of oceanic ridges. Seafloor spreading occurs at these elevated oceanic ridges and has high heat flow and volcanism.

What is the difference between continental drift and seafloor spreading?

Continental drift is a very similar process to seafloor spreading. Continental drift is the gradual movement of continental plates over the Earth’s surface over time. … Seafloor spreading is the formation of new areas of oceanic crust due to the upwelling of magma as oceanic aparts pull apart.

Where does seafloor spreading occur?

Sea-floor spreading is what happens at the mid-oceanic ridge where a divergent boundary is causing two plates to move away from one another resulting in spreading of the sea floor. As the plates move apart, new material wells up and cools onto the edge of the plates.

Where is the youngest material in the seafloor found?

The youngest crust of the ocean floor can be found near the seafloor spreading centers or mid-ocean ridges. As the plates split apart, magma rises from below the Earth’s surface to fill in the empty void.

Why was Alfred Wegener’s theory not accepted?

The main reason that Wegener’s hypothesis was not accepted was because he suggested no mechanism for moving the continents. He thought the force of Earth’s spin was sufficient to cause continents to move, but geologists knew that rocks are too strong for this to be true.

What are the 3 theories of plate tectonics?

Plates interact at three types of plate boundaries: divergent, convergent and transform. Most of the Earth’s geologic activity takes place at plate boundaries. At a divergent boundary, volcanic activity produces a mid ocean ridge and small earthquakes.

What are the two theories behind why tectonic plates move?

The convection currents move the plates. Where convection currents diverge near the Earth’s crust, plates move apart. Where convection currents converge, plates move towards each other. The movement of the plates, and the activity inside the Earth, is called the theory of plate tectonics.

Who proposed the theory of seafloor spreading?

Harry HessSea-floor spreading — In the early 1960s, Princeton geologist Harry Hess proposed the hypothesis of sea-floor spreading, in which basaltic magma from the mantle rises to create new ocean floor at mid-ocean ridges.

Who gave seafloor spreading theory?

Alfred Wegener produced evidence in 1912 that the continents are in motion, but because he could not explain what forces could move them, geologists rejected his ideas. Almost 50 years later Harry Hess confirmed Wegener’s ideas by using the evidence of seafloor spreading to explain what moved continents.

What was Arthur Holmes theory?

Holmes primary contribution was his proposed theory that convection occurred within the Earth’s mantle, which explained the push and pull of continent plates together and apart. He also assisted scientists in oceanographic research in the 1950s, which publicized the phenomenon known as sea floor spreading.

What did Alfred Wegener use as evidence for his theory that the continents were once one giant land mass?

Evidence for continental drift Wegener knew that fossil plants and animals such as mesosaurs, a freshwater reptile found only South America and Africa during the Permian period, could be found on many continents. He also matched up rocks on either side of the Atlantic Ocean like puzzle pieces.

What did Harry Hess contribute to the theory of plate tectonics?

Dr. Hess’ most significant contribution to the plate tectonic theory began in 1945 when he was the commander of the U.S.S. … In the paper Hess described how hot magma would rise from under the crust at the Great Global Rift. When the magma cooled, it would expand and push the tectonic plates apart.

What are 3 pieces of evidence for the theory of 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. This evidence led scientists to look again at Wegener’s hypothesis of continental drift.

How does the theory of plate tectonics support the theory of seafloor spreading?

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. … At a spreading center, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed.

What was Hess’s theory?

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.