LIFE may have survived a cataclysmic global freeze some 700 million years ago in pockets of open ocean.
Researchers claim to have found evidence in Australia that turbulent seas still raged during the period, where micro-organisms may have clung on for life. Conditions on what is dubbed Snowball Earth were so harsh that most life is thought to have perished.Details are published in the journal Geology.
The researchers in Britain and Australia claim to have found deposits in the remote Flinders Ranges in South Australia which bear the unmistakable mark of turbulent oceans.They say the sediments date to the Sturtian glaciation some 700 million years ago, one of two great ice ages of the Cryogenian period associated with the Snowball Earth hypothesis.
These sediments, they say, prove pockets of open ocean waters must have existed during the period, perhaps supporting microscopic life.
The Snowball Earth hypothesis suggests the land and oceans of our planet were thrown into a deep freeze, the like of which has never been seen before or since. “For the first time, we have very clear evidence that storms were affecting the sea floor,” said Dr Dan Le Heron of Royal Holloway, University of London. “That means we have to have pockets or oases within this Snowball Earth that are free of ice. “We see a very particular type of feature in sedimentary rocks called ‘hummocky cross-bedding’. These features can only form where storm waves sweep up sand from the ocean floor, slosh it back and create a bed of sandstone.”
Source: The Nation