To the Annual Review of Astronomy and Physics:

In 1872, scientists were taking a look at the sea floor using very long cables. They found a large mountain ridge in the middle of the Atlantic ocean that stretched a long way south. Now, they didn't think much of it at the time. However, in 1925, German scientists used sonar to confirm that there was in fact a mountain range stretching the entire length of the atlantic ocean. These ridges underwater kept being further explored, which is when I started to see for myself what the fuss was about. While I served the US army in WWII, I used sonar to map the pacific ocean's sea floor. There, I found many mountains, which was when I realised that new crust was constantly being formed, causing these imperfections on the seafloor. I call this process, seafloor spreading. I hypothesised that the Earth wasn't spreading just from Wegener's theory of continental drift, but also from seafloor spreading. My pieces of evidence for this are magnetic striping, the age of the seafloor and the thickness of the sediment. Magnetic striping is where the magnetic iron oxide mineral called magnetite lines up with Earth's magnetic field to point in the same direction. It is when strips of rock have alternating magnetism. This allows geologists to prove how new crust was formed. The age of the seafloor support's my theory by dating rocks and sediment that are both closer and further away from the main continents. Sediment thickness is another piece of evidence as it was found that the layers became thicker as you moved away from the ridges. This was interpreted by geologists and myself as showing that sediments had been falling for longer on the rocks on the sea floor furthest away from the ridges. These are the 3 types of evidence to support my theory.

Yours sincerely,
Harry Hess

To the Annual Review of Astronomy and Physics:

In 1872, scientists were taking a look at the sea floor using very long cables. They found a large mountain ridge in the middle of the Atlantic ocean that stretched a long way south. Now, they didn't think much of it at the time. However, in 1925, German scientists used sonar to confirm that there was in fact a mountain range stretching the entire length of the atlantic ocean. These ridges underwater kept being further explored, which is when I started to see for myself what the fuss was about. While I served the US army in WWII, I used sonar to map the pacific ocean's sea floor. There, I found many mountains, which was when I realised that new crust was constantly being formed, causing these imperfections on the seafloor. I call this process, seafloor spreading. I hypothesised that the Earth wasn't spreading just from Wegener's theory of continental drift, but also from seafloor spreading. My pieces of evidence for this are magnetic striping, the age of the seafloor and the thickness of the sediment. Magnetic striping is where the magnetic iron oxide mineral called magnetite lines up with Earth's magnetic field to point in the same direction. It is when strips of rock have alternating magnetism. This allows geologists to prove how new crust was formed. The age of the seafloor support's my theory by dating rocks and sediment that are both closer and further away from the main continents. Sediment thickness is another piece of evidence as it was found that the layers became thicker as you moved away from the ridges. This was interpreted by geologists and myself as showing that sediments had been falling for longer on the rocks on the sea floor furthest away from the ridges. These are the 3 types of evidence to support my theory.

Yours sincerely,
Harry Hess

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