Ancient lava 'rafts' possible life source

OXFORD, England, Sept. 13 (UPI) -- Rafts of pumice, volcanic rock that can float, could have been cradles of life on ancient Earth, some British and Australian scientists suggest.

The environments and locations where life emerged sometime before 3.5 billion years ago remain largely mysterious, with candidates ranging from warm, shallow ocean waters to deep-sea hydrothermal vents.

English and Australian scientists have suggested pumice, a pale volcanic rock rich in gas bubbles that can float on the surface of the sea, could have harbored the diverse ingredients and processes necessary for the development of life, LiveScience.com reported Tuesday.

Such floating rafts of lava froth could have been exposed to, "lightning associated with volcanic eruptions, oily hydrocarbons and metals produced by hydrothermal vents, and ultraviolet light from the sun" as they bobbed on the ocean surface, researcher Martin Brasier, an astrobiologist at Oxford University, said.

"All these conditions have the potential to host or even generate the kind of chemical processes that we think created the first living cells."

The pumice rafts eventually would have washed ashore on ancient coastlines, researchers said.

"We know that life was thriving between the pores of beach sand grains some 3,400 million years ago," researcher David Wacey of the University of Western Australia said. "What we are saying here is that certain kinds of beach might have provided a cradle for life."