Seafloor Spreading Facts: Theory, Dangers And Much More For You

Seafloor spreading is a geological process.

Volcanic activity often leads to a new oceanic crust formation on the oceanic floor. This activity causes older rocks to move away from the mid-oceanic ridge, due to which seafloor spreading occurs.

It means that the tectonic plates of the Lithosphere shift and split apart from each other. This theory was one of the first hypotheses to discuss the concept of the movement and development of the seafloor.

This theory played an essential role in the development of plate tectonics. It was a raging field of discussion during the late 20th century. The researchers are still working on understanding the formation of new oceanic crusts and the differences in rock densities around the ridge.

After the Second World War, various vessels equipped with SONAR helped with the research. The experts were able to collect ocean-depth profiles as they traveled across. Mary Tharp, an American oceanic cartographer, created several maps. The maps revealed the presence of the newly-formed Mid-Atlantic Range in 1953.

It was about 10,000 mi (16,093 km) long. This incident intrigued the interest of several geophysicists across the world. That included Harry H. Hess.

Earth science experts state that the material in this range's upper mantle rises through the oceanic plate gap. This concept leads to the development of a new crust. It develops as the plates move away. Further, the new crust also moves away from the ridge, making it a hub for volcanos and earthquakes.

Theory Of Seafloor Spreading

Harry H. Hess, an American geophysicist, proposed the theory of seafloor spreading in 1960. Hess could map the ocean floor using a SONAR. He soon discovered the Mid-Atlantic Ridge, also known as the mid-ocean ridge. The temperature near the Mid-Atlantic Ridge was comparatively warmer than the surface away from the ridge.

Hess then concluded that this warmer temperature must have been caused by the magma leaking out from this ridge. The ocean crust melts into magma. This magma could go back to the mantle or burst through a crack. If it goes back to the mantle, seafloor spreading becomes inevitable.

This new theory complimented Alfred Wegener's Theory of Continental Drift proposed in 1912. It is a hypothesis about the shifts in the position of the Earth's surface. This theory also implies that the age of the seafloor and the rocks have not been the same throughout the ages. They have been subject to constant changes over time.

According to Hess, this process of seafloor spreading occurs at the mid-ocean ridges. It is where volcanic activity creates new oceanic crusts and thus begins the oceanic floor's spreading. Hess' theory proposed that the seafloor moves and carries continents.

The theory further states that the radioactive chemicals in the earth's mantle will generate a huge amount of heat. Due to this, convection currents will also emerge. These rising currents form the oceanic ridges on the seafloor, and trenches are formed where the failing limbs meet.

Molten material erupts from the mantle, pushing out the older rocks as it spreads. A new ocean floor begins to form along the ocean crust's cracks. This entire process of seafloor spreading continues to add new and extra layers to the ocean floor.

Dangers Of Seafloor Spreading

There are some limitations to the seafloor spreading theory by Harry H. Hess. Hess' theory never quite explained the features of the ocean floor. Also, it did not explain the movement of these across different continents. This theory also didn't mention anything about the lithospheric tectonic plates.

The most important danger of seafloor spreading is that there is a probability that the sea level could rise. It could be a consequence of this process, which will lead to a depletion in landmass. It can further lead to settlement issues for the growing population. Furthermore, this will also affect the agricultural practices of the landmass.

Another danger is that the carbon dioxide in the atmosphere will also be affected. It would be because of the active volcanoes present. Frequent seismic movement within the seafloor can cause oceanic earthquakes. These can easily cause tsunamis. These, in turn, will affect the coastal areas of the landmass.

Past Seafloor Spreading Events

Seafloor spreading can occur along the mid-ocean ridges. They are enormous mountain ranges rising from the ocean floor. For instance, the South American and African plates are divided by the Mid-Atlantic Ridge.

It also separates the North American plate from the Eurasian plate. The Pacific plate is divided from the North American, Cocos, Nazca, and Antarctic plates by the East Pacific Rise. This mid-ocean ridge runs through the eastern Pacific Ocean.

The Southeast Indian Ridge shows the diverging border between two places. Those are the southern Indo-Australian and Antarctic plates. All mid-ocean ridges exhibit inconsistent seafloor spreading.

The African and Arabian tectonic plates split apart to form the Red Sea. It is a new geographical feature. The Red Sea and the Mediterranean Sea will eventually converge. It happens due to the seabed spreading, completely separating the two continents.

The seafloor spreading in the three major ocean basins shows the relative age of the ocean crust. The ocean basins include the Pacific, Arctic, and Atlantic. The continents migrate apart due to the sea spreading.

It produces an ocean floor that is increasingly younger. The width of the ocean basin is expected to increase. For instance, the continents that border the Atlantic Ocean are thought to be drifting away from the Mid-Atlantic Ridge.

Wherever deep-sea trench systems surround continents, like in the Pacific Ocean, the ocean floor plunges lower. It leads to underthrusting of the continents. This happens before they start re-entering and disintegrating in the Earth's mantle, where it came from.

As the weak upper mantle faces convection, the seafloor spreading starts. There is also a discussion about the ocean floor moving on its own as it expands from a mid-ocean ridge.

The earth science experts and geological society members expect to learn more about this process based on further research. They are working on the new crust formation and subduction zones to support this theory.

FAQs

What are the three types of evidence for seafloor spreading?
There are three main pieces of evidence for seafloor spreading. The list includes molten materials, seafloor drilling, and magnetic stripes.

What causes seafloor spreading?
Mantle convection is responsible for seafloor spreading and other tectonic activity.

Where does seafloor spreading begin?
Seafloor spreading happens at divergent plate borders.

How is the crust moving at a zone of seafloor spreading?
The tectonic plates gradually move away from each other. It happens as the seafloor spreading occurs along divergent plate borders. The crust eventually cracks and magma seeps through.

Who came up with the theory of seafloor spreading?
Harry H. Hess, an American geophysicist, presented the seafloor spreading concept in 1960. Hess made predictions based on Tharp's research and other discoveries regarding the deep seafloor.

What evidence supports seafloor spreading?
Investigations into oceanic magnetic anomalies have supported the theory of seafloor spreading.

What is the evidence for seafloor spreading?
Radiometric age dating, fossil ages, seafloor drilling, magnetic stripes, and analyses of the molten material were used to gather evidence for seafloor spreading.