Science Project

Alexander du Toit was a South African geologist who helped form the continental drift theory and plate tectonics. In 1932 he went to South America to compare the geology of the two continents. He saw that they were similar in multiple ways which supported Alfred Wegener's theory of continental drift.

When Hugo Benioff was a teenager he was interested in astronomy and most likely would have become an astronomer but he couldn't stand the night hours and the cold. In 1924 he became an assistant physicist with the seismological program at the Carnegie Institution in Pasadena. In 1929 Benioff made the first, world-famous seismograph and the linear strain seismograph. It was first built with a water pipe and didn't have much stability but it continued to change and evolve until 1934, which is when the final form was built. The seismograph was immediately successful. It was capable of very high magnification at a frequency of about 1 Hertz and was useful for the study of near and distant earthquakes. It made possible the precise determination of travel time, the discovery of new seismic phases, the extension of the magnitude scale to teleseismic events, and the availability of first-motion data to recover source mechanism. It is now used in every country in the world. In 1936 Benioff made instruments for seismic prospecting. Benioff proposed the idea of subduction of the seafloor.

Sir Edward Bullard made important contributions to every branch of twentieth-century geophysics. In 1967 he discovered that the Western Europe and American shorelines were closely matched at a depth of 500 fathoms. He also developed a theory to explain the origin of the Earth's magnetic field.

Around 1910, Wegner began looking into the proposal that in the Late Paleozoic era, all present-day continents had been one big supercontinent, which had broken apart. Wegner called this ancient world, Pangaea. The scientist then began stating that Pangaea’s continental parts had slowly moved thousands of miles apart over long periods of time. He called this movement die Verschiebung der Kontinente, or continental displacement which soon became known as continental drift. To prove his proposal, Wegner needed evidence. Wegner found closely related fossil organisms and similar rock strata in both the Americas and in Africa. Wegner’s theory of continental drift was practically forgotten until the 1960’s , where it was soon a part of the theory of plate tectonics.

Robert S. Dietz proposed the theory of seafloor spreading in 1961. He was a geophysicist and oceanographer. In 1952 he discovered the first fracture zone in the Pacific Ocean. That led him to hypothesize that new crust is formed at oceanic ridges and spreads outward several centimeters per year. His suggestion was soon confirmed.

Wadati brought up conversing evidence of deep earthquakes. He discovered what is known as the Wadati-Benioff Zone, an area of intermediate and deep earthquake zones along ocean trenches, which is now the foundation for the theory of plate tectonics.

Holmes had a hypothesis that the radioactive decay which occurs in the mantle, would generate heat. Then convection currents would be the reasons for moving continents.

Ocean floor mapping lets people know what the bottom topography of the ocean is like. Mapping the seafloor is called bathymetry.
A magnetometer is used to measure the strength or the direction of magnetic fields. Earth's magnetic field, mostly. Sheldon Breiner invented the magnetometer.
Geologists usually know the age of a rock by determining the age of the group of rocks or formation it is found in. The age of formations is marked on a geologic calendar known as the geologic time scale.

Hess proposed that molten material from earth's mantle constantly erupts along crests of mid ocean ridges. As the magma cools, it is pushed further and further away from the ridges. As time goes on, the older the rocks are, the closer they will be to the continent. The younger the rocks are, the closer they are to the ridges. This theory was called seafloor spreading.

These two geologists started working together when Vine was a PhD student under Matthews at Cambridge University. Their work was focused on the patterns of magnetic stripes on the ocean floor. They figured that if Henry Hess was right the symmetrical pattern of stripes wasn't an accident. They thought it indicated that the Earth's magnetic field switches direction over time. It goes from its current direction and switches to the reversed direction. Vine and Matthews saw that there was a symmetrical pattern of magnetic stripes on either side of the mid ocean ridges. It was suggested that the ocean floor was created at the mid ocean ridges, then split in half and pushed sideways. They published the idea in 1963 and it became known as the Vine-Matthews hypothesis. It became the first scientific test of seafloor spreading, and a crucial development in the theory of Plate Tectonics.