Chill winds keep the ravages of time at bay

Posted by pt91 at Nov 30, 2010 11:55 AM |
As the winter cold sets in across Britain, it might be a sobering thought that geologists at Leicester have discovered that fierce glacial winds are behind the preservation of fossils in Africa.

Dr Sarah Gabbott, Dr Jan Zalasiewicz and their colleagues from our Department of Geology have investigated a site near Table Mountain in South Africa.

The researchers conducted microscopic analysis of the shale layers using a specially designed ‘Petroscope’, obtained with funding from the Royal Society, that revealed remarkable and so far unique structures – myriads of silt grains, neatly wrapped in the remains of marine algae. 

The significance of this find casts light on both why there was such an abundance of life in the shale and how the remains of such life, normally consisting only of bone and shell, were so well preserved. The authors explain:

The silt grains are sedimentary aliens - much bigger than the marine mud flakes in which they are embedded.  They could only have been blown by fierce glacial winds on to the sea surface from that distant landscape.  Arriving thick and fast, they carried nutrients into the surface waters, fuelling its prolific life.  The deep waters, though, were overwhelmed by rotting, sinking vegetation, becoming stagnant and lifeless – ideal conditions to preserve the animal remains, down to their finest details. A cold wind, here, was key to both life and death.”

The research, conducted in collaboration with Stellenbosch University, has been published in Geology.