Plate tectonics theory was born by looking at the ocean floor. During second world war, in the Atlantic, there was huge effort by both parties to obtain good quality maps of the ocean floor. This was to drive/combat the german U-boats.
In addition, "new" sensitive magnetic devises were developed to detect large bodies of steel (e.g. submarines).
After war (during 50's and 60's) these new data came out and researchers found several striking features: first, the ocean basis were not deeper in the middle but, on the contrary, were deeper just by the continents. In the middle they found a mountain chain that goes from pole to pole with an average height os 5000m (over seafloor, still submerged). Actually this is the larger mountain chain on Earth.
Second, they found that seafloor rocks have a permanent magnetization. This is not surprising giving their composition, but the ming blogging feature is that this magnetization has a clear pattern of stripes parallel to the mid Atlantic mountain chain.
These two observations, that didn't fit at all with the theories of Earth evolution of the moment, were the main triggers of the new Plate Tectonics theory.
Nowadays, despite there is little doubt on how the Earth and oceanic plates behave, it is not clear how is the exact mechanism driving tectonic plates.
The thermal state of tectonic plates, hot at the mid oceanic ridge and cold near continents, explains the observed bathymetry. Nevertheless there is no agreement in the geophysical community on how this cooling happen. The first order is absolutely clear, but if you go to the details two theories compete to explain observations (the so called "half-space cooling" vs. "Plate Model"). Detailed bathymetry is key to distinguish which one is closer to what happen in Nature. We need better observations that the currently available to advance in our understanding.
Plate tectonics theory was born by looking at the ocean floor. During second world war, in the Atlantic, there was huge effort by both parties to obtain good quality maps of the ocean floor. This was to drive/combat the german U-boats. In addition, "new" sensitive magnetic devises were developed to detect large bodies of steel (e.g. submarines). After war (during 50's and 60's) these new data came out and researchers found several striking features: first, the ocean basis were not deeper in the middle but, on the contrary, were deeper just by the continents. In the middle they found a mountain chain that goes from pole to pole with an average height os 5000m (over seafloor, still submerged). Actually this is the larger mountain chain on Earth.
Second, they found that seafloor rocks have a permanent magnetization. This is not surprising giving their composition, but the ming blogging feature is that this magnetization has a clear pattern of stripes parallel to the mid Atlantic mountain chain.
These two observations, that didn't fit at all with the theories of Earth evolution of the moment, were the main triggers of the new Plate Tectonics theory. Nowadays, despite there is little doubt on how the Earth and oceanic plates behave, it is not clear how is the exact mechanism driving tectonic plates.
The thermal state of tectonic plates, hot at the mid oceanic ridge and cold near continents, explains the observed bathymetry. Nevertheless there is no agreement in the geophysical community on how this cooling happen. The first order is absolutely clear, but if you go to the details two theories compete to explain observations (the so called "half-space cooling" vs. "Plate Model"). Detailed bathymetry is key to distinguish which one is closer to what happen in Nature. We need better observations that the currently available to advance in our understanding.