Cover Article in Geological Society Journal is by ODU's Nora Noffke
Old Dominion University geobiologist Nora Noffke is the author of the cover article in the October issue of the Geological Society of America journal, GSA Today. The article is headlined, "Turbulent Lifestyle: Microbial Mats on Earth's Sandy Beaches-Today and 3 Billion Years Ago."
Noffke, who is an associate professor of ocean, earth and atmospheric sciences, was invited to write the article. It describes research she has pioneered showing that microbial mats that cover tidal flats today also existed 3 billion years ago. She has found evidence of Earth's earliest life in the geological record in South Africa.
Her work has helped to coin the term "microbially induced sedimentary structures," also called MISS.
Earlier this year, the journal Nature published a review of Noffke's research, accompanied by photos of 3 billion-year-old sandstones that Noffke discovered close to the village of Nhlazatse, South Africa. They contain preserved geological structures that hold clues about the microbes believed to have been the planet's first life forms. In the GSA Today article, Noffke states that 16 types of MISS are generally recognized, and she gives detailed explanations and illustrations for several.
Her research shows that MISS are reliable biosignatures, contributing significantly to the information provided by other geobiological evidence in dating earliest life.
Revelations about the Nhlazatse discoveries were published originally in a special January 2008 issue of the journal Geobiology, providing some of the sturdiest evidence yet that life forms had colonized sandy coasts of Earth by the time of the Archean Age, which ended 2.5 billion years ago.
Noffke's discoveries over the past decade have helped to answer questions scientists have long grappled with: Which microbes were the earliest living organisms, and where in the geological record can we find irrefutable evidence of the existence of such tiny life forms? She says most likely cyanobacteria-photoautotrophic and oxygen-producing microbes-had colonized some sandy coasts by 3 billion years ago and, amazingly, that they still can be found on coastal shorelines today.
The latest research on rocks in South Africa has turned up a virtual treasure trove of geological samples supporting her case that the microbial mats we see today covering tidal flats also were present as life was beginning on Earth. The mats, which are woven of cyanobacteria, can cause unusual sedimentary structures in the sand beneath them. Along today's beaches near ODU in Virginia and North Carolina, Noffke has identified numerous such structures caused by present-day microbial mats, and she has found corresponding formations in rocks dating back through the ages. The latest samples from South Africa are the oldest known and the best preserved.
Among the co-authors of the Geobiology article are former ODU graduate student Dina Bower and Don Swift, ODU's Slover Professor of ocean, earth and atmospheric sciences.
Noffke's research has opened a new window into the understanding of the rise of life. Although it seems certain that early life on Earth involved microbes, scientists have found it difficult to turn up evidence of organisms that lived many millions of years ago and were only a few millionths of a meter long. Until now, only the filigrane fossils of smallest bacteria found in glass-like flintstone or the "stromatolites," which are domes formed by early photoautotrophic microorganisms, seemed to constitute an archive for the investigation of early life.
However, the MISS are now helping to decipher life during the Archean time period (2.5 - 3.9 billion years ago).
Other geochemists and paleobiologists have produced evidence suggesting that life was
present on Earth perhaps as early as 3.8 billion years ago. Nevertheless, the evidence can be disputed-and often is both by scientists and creationists-particularly because fossil evidence can be mimicked by purely physical processes. For example, carbon believed to have organic origins can in fact be inorganic.
Noffke argues that her MISS samples, which she says definitely contain traces of organic material in the 3 billion-years-old rocks, are very reliable in establishing when life started, and likely will contribute to our knowledge about paleoclimates. She also predicts that geobiological methods may someday help decide whether there has been life on other planets.