“It is probably one of the largest floods ever identified,” said Phillip Gibbard, a geographer at the University of Cambridge who wasn’t involved in the study. At its peak, the flood would have discharged water at a rate of about 264 million gallons (a million cubic meters) a second, gushing at speeds of up to 62 miles (100 kilometers) an hour, the researchers say. This is roughly equivalent to ten times the combined flow rate of all the rivers in the world.

In addition to making Britain an island, the authors add, the huge flood had wide-ranging environmental consequences. For example, the gigantic pulse of freshwater entering the Atlantic Ocean likely caused a period of climate cooling in the Northern Hemisphere, Gibbard said. “The introduction of ice and freshwater into an ocean drives climate oscillations and causes marked cooling events,” he explained.

The flood also marooned many animals and plants, so those species gradually evolved into different forms than their mainland cousins.

In the early 1990s, a Russian drilling rig encountered something peculiar two miles beneath the coldest and most desolate place on Earth. For decades, the workers at Vostok Research Station in Antarctica had been extracting core samples from deep scientific boreholes, and analyzing the lasagna-like layers of ice to study Earth’s bygone climate. But after tunneling through 414,000 layers or so– about two miles into the icecap– the layers abruptly ended.
…
Unbeknownst to the Russians, their drill had mingled with the uppermost reaches of one of the largest freshwater lakes in the world; a pristine pocket of liquid whose ecosystem was separated from the rest of the Earth millions of years ago. As for what sort of organisms might lurk in that exotic environment today, no one can really be certain.
…
Extremophile organisms have turned up in the unlikeliest of places, including within volcanic vents on the ocean floor, in the rocks deep in the Earth’s crust, and in frozen arctic soil. It is not unreasonable to suggest that cold-tolerant creatures could thrive in the waters of Lake Vostok, overcoming the oxygen saturation with extraordinary natural antioxidants. But millions of years of evolutionary isolation in an extreme environment may have created some truly bizarre organisms. This notion is supported by the ice samples drawn from the ice just above Lake Vostok, where some unusual and unidentifiable microbial fossils have been found. But the possibility that they are merely contaminates has not yet been completely ruled out.