It may have begun rising more than 30 million years ago.
Plate tectonics is relatively new, put forth in the last 30 years or so — its forerunner was the now-discarded continental drift theory. The theory states that Earth's outer shell is made up of huge slabs of rock called plates that glide over the planet's inner layer, or mantle. As these plates shift, they sometimes collide with other plates, making for some interesting, and even deadly, results on Earth's surface, from erupting volcanoes, to earthquakes, to new mountain ranges. Here's a look at Live Science's news and features related to this constantly moving jigsaw puzzle.
The mantle under the Manus Basin appears to contain highly distilled ancient water that is mixing with modern seawater.