Researchers uncovered traces of a lost continent that disappeared under what is today Europe about 120 million years ago.
Geologists have seen hints of the continent, dubbed Greater Adria, for years. But the Mediterranean area is incredibly complicated, so piecing together its history took a decade of academic detective work. “The Mediterranean region is quite simply a geological mess,” geologist Douwe van Hinsbergen of Utrecht University, first author of the study in Gondwana Research says. “Everything is curved, broken, and stacked.”
The story that the rocks tell begins on the supercontinent Gondwana, which would eventually split into Africa, South America, Australia, Antarctica and India. Greater Adria broke away from the mother continent about 240 million years ago, beginning a slow drift northward. Roughly 140 million years ago, it was about the size of Greenland, mostly submerged in a tropical sea, collecting sediment that hardened into rock. Then, roughly 100 to 120 million years ago, it hit the southern edge of future Europe, spinning counterclockwise and moving at about 3 to 4 centimeters per year.
As Robin George Andrews at National Geographic reports, the destruction of Greater Adria was complex. It hit several subduction zones, or areas where tectonic plates meet. In this case, the Greater Adria plate was trumped by the European plate, and most of it dove down into Earth’s mantle. The overlying plate scraped the top layers of Great Adria off. That debris eventually formed mountain ranges in Italy, Turkey, Greece, the Balkans and in the Alps. A few bits of Greater Adria escaped the plunge into the mantle and still exist in Italy and Croatia.
Figuring out the story of Greater Adria was difficult, not only because of the geology but also due to human factors. Information about the continent is spread across many countries, from Spain to Iran. “Every country has their own geological survey and their own maps and their own stories and their own continents,” Hinsbergen tells Yasemin Saplakolu at LiveScience. “[With this study] we brought that all together in one big picture.”
They also spent time constructing the continent’s history by examining the orientation of tiny magnetic minerals created by bacteria trapped in the Adria rocks. From that data they were able to understand how much the rock layers rotated over time. They also pieced together structures like strings of volcanoes and coral reefs. New, more powerful software developed over the last 15 years or so also aided in reconstructing the lost land mass.
Sid Perkins at Science reports that the new study isn’t the only evidence for Greater Adria. In 2016, another team identified slabs of the continent in Earth’s mantle using seismic waves. Nor is it the only “lost continent” out there. A large land mass called Zealandia is submerged under two-thirds of a mile of water in the South Pacific and is considered the “eighth contienent” by some researchers. In 2017, other scientists announced that they found a sunken “mini-continent” under the island of Mauritius in the Indian Ocean.