* Astronomy

Volcanic rock discovery could reveal secrets of Earth's history

Geologists in Scotland have discovered a completely new type of volcanic rock, which they believe will help to pinpoint the precise time in Earth's history at which life emerged from the oceans and began to colonise the land.



Discovered in Torridon by an amateur geologist who works at St Andrews University, the rocks have been identified as important because they contain the bacteria and microbes which are thought to have formed the first terrestrial life on the planet.
Other such deposits found in Scotland have so far proved very difficult to date.
Experts currently believe that the Metazoan period - which was when simple forms of life such as bacteria and algae first appeared on land - was somewhere in the region of 1,000 million years ago.



However, because the new rocks contain an element called zircon - which is radioactive and can be far more accurately dated - scientists believe that they will be able to narrow the figure down further by tens of millions of years.



Richard Batchelor, an administrator at St Andrews University, said: "(From our examination) we believe the rocks contain fossilised microbes, and these would have formed on the surface in little mud pools.
"This is the key," Mr Batchelor explained. "The surface of the rocks has been scrunched up, and this represents indirect evidence for these bacteria.
"It is very strong evidence of the fact that there was life on the surface of the land in a very specific time band that we will be able to date, so it's an important discovery."

The volcanic rocks will now be examined and dated using mass spectrometry techniques.

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