The uncertainty of science: Based on data covering the last 19 million years, scientists now believe that the rate in which the Earth’s ocean sea floors are spreading has been slowing steadily.
Today, spreading rates top out around 140 millimeters per year, but peaked around 200 millimeters per year just 15 million years ago in some places, according to the new study. The study was published in the AGU journal Geophysical Research Letters, which publishes high-impact, short-format reports with immediate implications spanning all Earth and space sciences.
The slowdown is a global average, the result of varying spreading rates from ridge to ridge. The study examined 18 ridges, but took a particularly close look at the eastern Pacific, home to some of the globe’s fastest spreading ridges. Because these slowed greatly, some by nearly 100 millimeters per year slower compared to 19 million years ago, they dragged down the world’s average spreading rates.
You can read the actual paper here.
To put it mildly, the conclusion here is uncertain. The difference between 140 and 200 millimeters is less than two and a half inches. A hundred millimeters is less than four inches. Such small differences over millions of years could simple be caused by random fluctuations over time. Furthermore, the scientists did not actually detect the spreading rates from millions of years ago. They instead inferred it based on the data we do have of the changes in the Earth’s magnetic field over time.
Still, this result is very intriguing indeed. More than anything, it should help geologists develop better theories to explain plate tectonics, and what drives it. At the moment no theory adequate explains it.
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