A 10,000 square kilometer (3,861 sq. mile) island sank beneath the waves long ago, in the frigid waters of the Atlantic north of Scotland.

No, it wasn’t Atlantis.

The landmass sank beneath the waves of the North Atlantic long before humans arrived on the scene.

The island was created when the Icelandic Plume, a bubble of magma beneath the Earth’s surface, forced the crust up and out of the water. The land was forced up in a series of three steps, each one pushing the land 200-400 meters higher.

The island popped up out of the water for about a million years. Long enough for land plants to colonize it. But it sank back down and now resides almost 2 kilometers (1.2 miles) beneath the ocean.

Contractors using echo-sounding technology to search for deep-sea oil found the lost world beneath the sediments and debris that accumulated in the 56 million years since the island sank northeast of the Orkney-Shetland islands.

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Echo-sounding involves the release of highly pressurized air beneath the water to create sound waves. The sound waves pass through sediments on the floor of the ocean. When the sound waves bounce back, a microphone records them. The data is then used to create a three dimensional map of what lies beneath the ocean.

Nicky White of the University of Cambridge and his team used those maps to observe the sunken island. They could even see what used to be rivers and mountains. Their findings were recently published in Nature Geoscience.

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The researchers also examined sediment samples from the sunken world and found traces of pollen and coal, suggesting land plants once resided there.

They speculate that the island may have even been part of a much larger landmass that once stretched from Scotland to Norway.

IMAGE 1: Orkney Islands, United Kingdom (Wikimedia Commons).

IMAGE 2: Shetland Islands from space (NASA).