Chemistry and Physics

Hunting For WW2 Submarines Helps To Prove Tectonic Plate Theory

Black and white image of a WW2 Germany U-boat being suspended in the air as it is lifted from the ocean
Sayumi Panditharatne

Did you know that, 300 million years ago, Britain used to be geographically very close to the equator, with temperatures hotter than the most recent summer days? Why are we closer to the north pole now? And why do mountains exist underwater?

In our pre-occupied lifestyles here on land, it’s easy to be oblivious to what happens literally right under our feet. Plate tectonics are a fascinating feature of our planet that has major influences on the Earth and its inhabitants. Its discovery came from an unexpected source: the Second World War.

Our planet is made up of four layers: the crust, the mantle and the outer and inner core. Large slabs of the upper mantle and the crust, known as the lithosphere, are called plates. The theory of plate tectonics describes that the lithosphere is dynamic, constantly moving and shifting, and not fixed in place as previously thought. This seminal discovery led to our understanding of the geological events which created the Earth as it is now.

Rapid technological developments during the Second World War backed Wegener’s theory

Alfred Wegener, a German meteorologist, was the first to theorise plate movements in the continental drift. In the early 20th century, he postulated that the Earth’s land masses may be “drifting” across the oceans, and that the supercontinent Pangaea broke up in the Triassic Period and formed separate continents.

This is evident when making the observation that the east coast of South America and the west coast of Africa fit together like a jigsaw puzzle. In 1915, he published his book ‘The Origins of Continents and Oceans’, but the havoc of the First World War found the publication held in low regard.

After Wegener’s death in 1930, rapid technological developments during the Second World War just happened to back up his theory in the years to come. Submarines were Germany’s strongest asset to winning naval battles in WWI, and by WWII, the allies began advancing their own submarines to counteract German attacks. One of their priorities was locating German axis submarines to destroy them. This brought about new technologies, one of them being the improved fluxgate magnetometer.

At the time, it was well understood that the Earth had its own magnetic field, imaginary lines of force that span the north pole and loop back to the south pole, due to currents generated by molten nickel and iron in the Earth’s core. The fluxgate magnetometer is a device which measures the strength, direction and changes in the magnetic field. The U.S. Navy used this to observe any anomalies in the magnetic field, for instance a distortion in the field due to the presence of metal objects such as submarines.

Russian-born American geophysicist Victor Vacquier, who was working on the fluxgate magnetometer, received funding from the U.S. Navy to make the device mobile in order to detect submarines. He and his team designed the device to be fitted on to the tails of aeroplanes. Now that the device was also more sensitive, it made locating enemy submarines possible by monitoring small changes to the Earth’s magnetic field.

After the end of WWII, due to the precision and new airborne feature of the magnetometer, scientists were interested in what the device could reveal about the magnetic field of the seafloor. In the 1960s, they used sensors carried by ships to analyse the magnetic patterns in underwater rocks.

Unexpectedly, when constructing maps from the data gathered, a pattern which resembled “zebra stripes” with alternating black and white “stripes” was generated, representing changes in the magnetic field through time. The black and white stripes accounted for rocks imprinted when the magnetic field was normal and reversed in direction, respectively.

This strange pattern was evidence that the sea floor moved, therefore solidifying the plate tectonics theory. The zebra patterns were seen in mid-ocean ridges- underwater mountains risen from the ocean floor which separate the plates from each other. The Earth’s crust pulls these apart, which causes the spreading of the sea floor.

Well, why are plate tectonics so important? For one, they have critical effects on the planet and the life of its inhabitants. Volcanic eruptions, earthquakes, landslides and tsunamis are consequences of sudden movements of the ocean floor. When two plates slide against each other, friction can cause one to become stuck. One plate can collide against the other with a release of energy similar to a spring bouncing back. In the case of tsunamis, it results in massive waves.

The discovery of the phenomenon of plate movements was one of the most significant scientific discoveries of all time

Tectonic plate activity is also considered to be a cause of the chronic changes in the Earth’s climate. At sloth-like rates, typically millimetres per year, the continents drift apart and collide. This causes a change in the planet’s ocean currents with the creation of mountains, which alters wind currents. This is an occurrence that has taken place over millions of years, forming the Earth to its present state.

Moreover, plate tectonics also considerably impact geopolitics – the influence of geographical factors on international relations – with or without plate-induced natural disasters, from 9.0 magnitude earthquakes in Japan, to oil monopoly in Saudi Arabia, to political instability in Russia.

The discovery of the phenomenon of plate movements was one of the most significant scientific discoveries of all time. Before studying plate tectonics, scientists could not explain how some parts of the Earth, such as Japan, were more prone to earthquakes than others, or how fossils discovered in entirely different continents were similar or identical to each other.

With all the drastic destruction that came with the Second World War, so came sophistications in science and technology. The fluxgate magnetometer is an example of this, an indispensable tool that rose from WWII, helping us illuminate our understanding of many unknowns. Studies of the Earth’s geology in the years that followed were made possible by the discovery of this ‘ground-breaking’ device.

Sayumi Panditharatne

Featured Photo by ww2gallery from Flickr. Image license found here. No changes were made to this image.

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