Harriman Park stars in film on N.Y. geology

2 billion years of tortured rock records on display in region's stony basement

August 18, 2002|By Glen Collins | Glen Collins,NEW YORK TIMES NEWS SERVICE

TOWN OF RAMAPO, N.Y. - "This is my Rosetta Stone," Alexander E. Gates was saying as he stood before a vast chunk of rock near Lake Tiorati in Harriman State Park. A video crew was capturing his every syllable.

"A single rock outcrop can reveal the entire geologic history of this park," he said.

"And this one shows evidence of a continental collision where two of the Earth's plates hit together, and then later, hot magma intruded at 1,000 degrees centigrade." He gestured toward the gray wall.

"That was great," the director, Mercedes Walker, said to Gates and his cameraman, Aaron Dubrow. "Now let's do the whole thing again."

And that's the way it goes in science show business. Gates, chairman of the Department of Earth and Environmental Sciences at Rutgers University in Newark, is the star of a new video documentary chronicling the last 2 billion years of New York's tortured rock record.

Center of geotourism

The video is just one of the tools Gates is planning to use to make Harriman State Park, one of the last vast, geologically pristine places in the region, the main attraction at a new center for geotourism.

"Geotourism is a relatively new phenomenon, but a lot of people are passionate about geology," Gates said. "That's why geology lovers always get into car accidents around outcrops - they're only looking at the rocks."

For many decades, most geological researchers have given short shrift to the New York region, Gates said, thanks to the spectacular topography - higher mountains, active volcanoes and deep canyons - of the West.

But the stony basement of the metropolitan area is actually one of the most complex in the United States, he said, with its dazzling variety of rocks and their intricate mille-feuille construction.

Gates and his scientific team have been working to establish a geological park in the unspoiled 50,000-acre outdoor laboratory of Harriman, in Rockland and Orange counties.

There is already a coterie of geology lovers who visit regions of the United States and Europe that are promoted as geological parks, complete with tours and self-guided itineraries. But Gates also envisions Harriman as an educational tool for scholars, teachers, schoolchildren and the general public.

The new Web site in progress marries a Harriman hiking map with starred views of geological interest, offering information about each outcrop that attempts to satisfy interest levels ranging from grade school to graduate school. It is an outgrowth of the work of Gates and his team, who, supported by a $75,000 grant from the National Science Foundation, have been mapping the rugged landscape of Harriman for the last six years.

His ambition has been not only to compile the most detailed picture of the geological history of Harriman and its region, but also to look for clues that might unravel important mysteries of Earth's lost supercontinents.

New insights

Already, in his earth-science sleuthing, Gates has shed new light not only on the pattern of local earthquakes but also on the Harriman watershed in a time of drought.

His research has also yielded revelations about the formation of the ancient continent of Rodinia about a billion years ago. He has identified 2 billion-year-old zircons in Harriman rocks, twice as old as any previous finds in the New York region.

This discovery has led Gates to the startling science-fictionish conclusion that "the Hudson Highlands of New York may have once been a part of South America."

The garnets discovered by Gates are about 2 billion years old, the record-holder for metropolitan-area geology.

This raises the speculation that portions of the Hudson Highlands rocks found in Harriman could be a remnant of another continental mass that slammed into what is now metropolitan New York.

Gates has located a preliminary match in Western South America, in the headlands of the Amazon River, which offers a similar geology.

It is possible that Harriman contains a remnant of what is now Brazil that was left behind when the continents pulled apart 600 million years ago.

Fault zones

For years Gates has also made a study of the earthquake-producing fault zones in Harriman. Though the New York area is often characterized as dormant, geologists say it presents the potential for earthquake hazard.

And so, thanks to Gates' urging, a seismograph was established in February in the Perkins Memorial Tower atop Bear Mountain, according to Won-Young Kim, research scientist at Lamont-Doherty Earth Observatory in Palisades, N.Y.

"It is quite fascinating to use this in mapping the fault zones there," said Kim, who set up the seismograph.

When Gates described the boundaries in Harriman of the Ramapo Fault, which stretches from Peekskill to Tuxedo, N.Y., scientists at Lamont checked their seismological records and discovered that the fault had produced several earthquakes of magnitude 2.3 in recent years.

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