Science reveals the Atlantis-like story of Greater Adria, a continent the size of Greenland that vanished 140 million years ago, not under the sea but below the slowly moving continent of Europe:
For starters, Greater Adria had a violent, complicated history, notes Douwe van Hinsbergen, a geologist at Utrecht University in the Netherlands. It became a separate entity when it broke away from the southern supercontinent of Gondwana (which comprised what is today Africa, South America, Australia, Antarctica, the Indian subcontinent, and the Arabian Peninsula) about 240 million years ago and started to move northward, scientists believe. About 140 million years ago, it was a Greenland-size landmass, largely submerged in a tropical sea, where sediments collected and slowly turned into rock. Then, as it collided with what is now Europe between 100 million and 120 million years ago, it shattered into pieces and was shoved beneath that continent. Only a fraction of Greater Adria’s rocks, scraped off in the collision, remained on Earth’s surface for geologists to discover.
Another complication is that Greater Adria’s rocks are dispersed across more than 30 countries, in a swath from Spain to Iran.
Rather than simply moving north with no change in its orientation, Greater Adria spun counterclockwise as it jostled and scraped past other tectonic plates, van Hinsbergen’s team reports this week in Gondwana Research. Although the tectonic collision happened at speeds of no more than 3 to 4 centimeters per year, the inexorable smash-up shattered the 100-kilometer-thick bit of crust and sent most of it deep within Earth’s mantle, van Hinsbergen says.