Much of Broken Ridge is covered in a sediment called foraminiferal ooze, made of plankton that died, settled and was compacted by the tremendous pressure from the water above.
“Think like it’s been snowing there for tens of millions of years,” said William Sager, a professor of marine geophysics at the University of Houston in Texas.
Like snow, the layer of microscopic plankton shells tends to smooth out any rises or falls in the underlying rock. In places, the layer is up to half a mile deep.
But if the fuselage of the Boeing 777 did fall on to Broken Ridge, it would not sink much into the muck.
“The surface would be soft; it would squeeze between your toes, but it’s not so soft that you would disappear like snow,” Sager said. “Something big like pieces of an airplane, it’s going to be sitting on the surface.”
Searchers will be hoping that if the latest area turns out to be where the plane crashed — and that remains educated guesswork until searchers can put their hands on aerial debris sightings and check what it is — the fuselage did not go down on the southern edge of Broken Ridge.
That’s where the ocean floor drops precipitously — more than 21/2 miles in places, according to Robin Beaman, a marine geologist at Australia’s James Cook University. It’s not a sheer cliff, more like a very steep hill that a car would struggle to drive up. At the bottom of this escarpment is the narrow Diamantina trench, which measurements put as deep at 19,000 feet, though no one is sure of its greatest depth because it has never been precisely mapped.
“Let’s hope the wreck debris has not landed over this escarpment — it’s a long way to the bottom,” Beaman said.