Volcanic rock rafts could have been cradles of life

Now, a team of British and Australian scientists suggest that rafts of pumice, which is essentially solidified lava froth, were instrumental as vessels for first life. This pale volcanic rock, which is rich in gas bubbles, is the only known rock type that naturally floats on the surface of the sea, the researchers said.

They argue that pumice floating on the sea would offer a way to bring together the diverse ingredients needed for life to develop, LiveScience reported. Researcher Martin Brasier, an astrobiologist at Oxford University, said that a raft of such rock would potentially be “exposed to, among other things, lightning associated with volcanic eruptions, oily hydrocarbons and metals produced by hydrothermal vents, and ultraviolet light from the sun” as it floated on the water.

“All these conditions have the potential to host or even generate the kind of chemical processes that we think created the first living cells,” he said. This porous rock has the greatest ratio of surface area to volume of any type of rock, offering plenty of space for key life chemicals to glom onto; these would include metals, phosphates and organic compounds.

Its many pores, Brasier said, could have essentially served as miniature caldrons of primordial soup, each acting as an ideal “floating laboratory” for the development of the earliest micro-organisms.

The pumice rafts eventually would have beached themselves along shorelines, said the researchers who detailed their findings in the September issue of the journal “Astrobiology”.