We know less about the deep ocean than we do about the surface of Mars. But if we want to really understand how humans are impacting the Earth, we need to start looking down deep into the muck. That's why scientists created the first digital map of the seafloor's geologic composition.
Other seafloor maps have used satellites and remote sensing instruments to trace underwater mountains and canyons. But the latest map, published in the journal Geology, is the first to describe the diverse sedimentary composition of the seafloor. And that's important, because patterns in sediments can help scientists unravel past environmental changes and predict our planet's future.
To construct the map, Adriana Dutkiewicz and her colleagues at the University of Sydney analysed the composition of nearly 15,000 seafloor samples, taken over half a century by research ships. The team settled on thirteen major classes of sediment, from silica-rich sands and silts to diatom oozes — the mass graveyards of the tiny marine organisms that produce 30% of the oxygen we breathe.
Diatoms tend to bloom in cooler, higher latitude waters following pulses of nutrients. Tracing their footprints on the seafloor may shed light on when conditions were cooler at the surface. The calcium carbonate-rich sediments produced by corals, certain mollusks and microorganisms are extremely pH sensitive, and could offer clues about past ocean acidity.
"The deep ocean floor is a graveyard with much of it made up of the remains of microscopic sea creatures called phytoplankton," Dutkiewicz said in a statement. "The composition of these remains can help decipher how oceans have responded in the past to climate change."
As a side-bonus, mapping projects are one of the rare instances in which geologists get to express their artistic side — which is why we wind up with images of the Earth that look a bit like kindergarten art projects.
Image via EarthByte Group, School of Geosciences, University of Sydne