SCIENCE

SCIENCE. Cont'd.

GEOLOGICAL TIME GETS A NEW PERIOD Geologists have added a new period to their official calendar of Earth's history - the first in 120 years.

Ediacaran fossil, Jim Ogg

Photo: Ediacaran organisms appear after a series of ice ages that covered the Earth

The Ediacaran Period covers some 50 million years of ancient time on our planet from 600 million years ago to about 542 million years ago. It officially becomes part of the Neoproterozoic, when multi-celled life forms started to take hold on Earth. However, Russian geologists are unhappy their own title - the Vendian - which was coined in 1952, was not chosen. The decision was taken after a fifteen-year long period of consideration by expert geologists. "There's always been a recognition that the last part of the Precambrian is a special time before the first shelled animals, when there are these mesh-like creatures of uncertain affinity," Professor Jim Ogg, secretary-general of the International Commission on Stratigraphy (ICS), told BBC News Online. "Now it's an official part of the timescale."

'Snowball' Earth: The Ediacaran begins at the end of the last ice age of the Snowball Earth, or Cryogenian Period, a term given to a series of glaciations that covered most of our planet between 850-630 or 600 million years ago. One theory proposes that these climate shocks triggered the evolution of complex, multi-celled life. The proposal had to pass three balloting stages, first by the members of the ICS's Terminal Proterozoic Period subcommission (which was set up specifically to consider the Ediacaran question), then by the ICS itself and finally by the International Union of Geological Sciences (IUGS) which ratified the definition in March. At each stage, the vote had to be passed by two-thirds of the voting members. However, Russian geologists are likely to continue to call the period by its alternative name: the Vendian.

Enorama Hills section, Ogg

Photo: Enorama Creek, Australia, was chosen as the global bench mark for Ediacaran rocks

In 1952, the Russian geologist Boris Sokolov coined the term Vendian for a system of sedimentary rocks in the former Soviet Union. The two Russian members of the Terminal Proterozoic Period subcommission and Dr Sokolov submitted a formal comment expressing their disappointment at the decision to choose the Ediacaran over the Vendian. "This decision ignores both the priority of the name Vendian and a long tradition to use this term in the international geological literature," Sokolov, Mikhail Semikhatov and Mikhail Fedonkin wrote in their comment. The name Ediacaran takes its name from the Ediacara Hills in the Flinders mountain range of south Australia. The name is of Australian Aboriginal origin and refers to a place where water is present. The Enorama Creek section of Flinders was designated the "boundary stratotype" for the Ediacaran by the Terminal Proterozoic Period subcommission. A boundary stratotype is a rock sequence defined and used as the standard comparison for all other rock sequences of its age.

GENE REVOLUTION "COULD HELP POOR"

Genetically modified crops could form part of the answer to world hunger, according to a United Nations report.

With the world population set to rise by two billion over the next 30 years, such crops could help meet food needs. Drought and insect-resistant crops could boost yields and incomes, the United Nations' Food and Agriculture Organization (FAO) says. But it warns that biotechnology is no panacea and must focus on the needs of developing countries. Global attitudes: The report comes days after the decision by US agri-chemical company Monsanto to stop marketing modified wheat because of consumer opposition. Commercial resistance to a strain of wheat called Roundup Ready has been so strong the company has decided to shelve its original plans. But the UN report suggests that although many Europeans are opposed to the idea of GM food on their plates, many in the developing world are not. It cites a survey in which the majority of those questioned in India, Colombia and Nigeria believed the benefits of biotechnology outweighed its risks.

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