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GEOLOGY, FOSSILS HELP LINK VOLCANOES AND EVOLUTION

Exploring shelves of rock in a remote part of the rugged Confusion Mountains 50 miles southwest of Delta, paleontologists recently discovered a link between ancient volcanoes, the greenhouse effect and evolution.

So says Mark A. Wilson, professor of geology at the College of Wooster in Wooster, Ohio. He and Thomas J. Palmer of the Institute of Earth Studies at the University College of Wales in Aberystwyth made the discoveries.Certain periods of Earth's history were marked by much greater levels of carbon dioxide than presently because movements of the planet's crustal plates caused a great deal of volcanism. Volcanoes belched carbon dioxide into the atmosphere and oceans for millions of years at a stretch.

The Ordovician era, 500 million to 440 million years ago, and the Jurassic, 210 million to 140 million years ago, were such periods.

Wilson and Palmer studied rocks in the Confusion range south of Notch Peak in Millard County, which were formed during the Ordovician era. In a telephone interview, Wilson said he thought the area, south of Notch Peak, was one of the most beautiful places he has visited.

The research was supported by the Luce Fund for Distinguished Scholarship and the American Chemical Society.

"In the shales are thin limestones," he said. "Many, if not most, of these thin limestone units were cemented up - they were turned into rock - on the ancient sea floor long before they were buried," he said.

Volcanism had a lot to do with that. Around 480 million years ago, so much CO2 fizzed through the air and sea that it formed calcite in the water, causing a reaction on the bottom. It turned soft, muddy sediments into huge sheets of rock called "hardgrounds."

"When these hardgrounds were made, they provided the first marine hard substrates (foundations) for organisms." Previously, animals like trilobites, sponges and soft-bodied creatures didn't attach themselves to hard surfaces because there weren't any; the animals were limited by their environment.

The new type of ocean floor meant that different kinds of animals could form colonies that were somewhat more permanent, anchored to the bottom. The new environment was exploited by two different kinds of inveterate animals, bryozoans and stemmed echinoderms.

And the researchers found plenty of fossils of both varieties on the ancient limestone hardgrounds.

Bryozoans were something like corals, which are micro-organisms with hard skeletons. The minute chambers would pile together into larger structures. "They look like brown mounds with tiny holes on them, and they're just attached directly to the rock," he said.

Echinoderms were the ancient forerunners of the modern sea lilies. They looked like plants, with stems and a lily-like head. They attached themselves to the new hard surfaces by special disks at the base of their stems. "We find these disks by the thousands, so they would live like a forest on these hard substrates," he said.

A variety of new animals exploded across the ocean floor as they proliferated and moved into the new ecological niche. "We think that these organisms that we see on these hardgrounds are new," he said. "We don't find them before this."

Evolution allowed new types of animals to develop "very quickly to exploit, to take advantage of this new environment." They moved into an ecological niche "where there's nothing else, where there's no competition."

His conclusion? "The evolution of life was controlled by more than just the interaction of organisms. It also was controlled by physical processes of the Earth itself."