As Continents Collide Mountains Arise, and Geologists Dig Icy Past : Tectonics: Satellite is to be used to take measurements from the Adirondacks to learn how old they are and if they are still rising. Findings will be compared with those gathered 130 years ago.

GARNET LAKE, N.Y. — After climbing a two-mile trail as steep as stairs and carrying his dog up two log ladders, Steve Tice knelt on the gneiss dome of Crane Mountain seeking a lump of bronze.

“It should be right around here,” the bearded young geologist murmured anxiously, recalling failed searches for similar benchmarks on other peaks.

Tice had ascended the icy summit in the southern Adirondacks, about 65 miles north of Albany, as part of a research project to determine how old the mountain range is, and if it is, in fact, still rising.

Geologist Steve Roecker of the Rensselaer Polytechnic Institute in Troy, N.Y., heads the project. He will use the Global Positioning Satellite next spring to take sophisticated measurements from Adirondack peaks.

Roecker will compare the space-age data to that gathered 130 years ago by Verplanck Colvin, who did the first survey of the region and whose eloquent field reports are cited as a major impetus to the creation of the Adirondack Forest Preserve, protected as “forever wild” by the New York Constitution.

But first, Colvin’s bronze survey markers must be located.

“I can’t dig out every one of these crevices,” Tice muttered, brushing sand from a hollow.

Then, uttering a sound of satisfaction, he pressed his fingertips to the object of his desire: a lump of metal the diameter of a quarter, nicked and ax-hacked by hikers and coated with a green patina the same shade as the lichen on the surrounding rock.

“This has got to be it,” Tice said, examining the benchmark with a magnifying loupe.

If Crane is one of the summits chosen for the research project, Roecker, Tice and graduate students will carry packs of equipment up the steep trail. They’ll put a satellite receiver dish the size of an eight-slice pizza atop a 5-foot-tall tripod centered over the Colvin marker, lock onto a satellite signal, then pack everything back down.

“We want to take readings from at least 10 locations,” Roecker said. That will require a lot of reconnaissance, since Tice had found only three Colvin markers on the first 10 mountains he had climbed.

“The main problem we’re trying to address is, are the Adirondacks uplifting in a significant way?” Roecker said.

To answer that, he will take satellite survey readings, which pinpoint positions to within 1 millimeter in 60 miles. He’ll compare those to data from Colvin and more recent surveyors, and determine if various established survey points are moving apart--which would indicate doming of the land.

“Even though the old surveys were far less accurate than what we’ll get with GPS, if the Adirondacks are moving up at a high rate, there should be enough displacement over the 30, 60, or, in Colvin’s case, 130 years, for us to see it,” Roecker said.

If the rise were 3 millimeters a year, for example, that would be 189 millimeters, or about 7 inches, of difference between the new readings and those taken in a 1931 survey.

“If the rise is much less than that, we might not be able to see it,” Roecker said, but future surveys with GPS accuracy will be able to detect smaller changes.

Roecker also will set up seismometers to record waves within the Earth to determine if a structure like a hot magma chamber is under the Adirondacks.

Yngvar Isachsen, principal geologist at the state Geological Survey in Albany, has long promoted the theory that the mountains are still growing.

“The Adirondacks are unusual in that they are a circular uplift,” Isachsen said. Most mountain ranges are linear, the result of the movements of the tectonic plates on which the continents ride like groceries on a conveyor belt.

The Rockies and Himalayas formed when tectonic plates collided, crushing and folding the Earth’s crust. The Appalachians formed when Africa and Europe crashed into North America during Precambrian times. Other mountain ranges formed as a result of volcanic activity along plate boundaries.

The Adirondacks, however, are 2,000 miles from a plate boundary.

“A circular mountain range like this is created by a vertical force,” Isachsen said. “And the only upward force known is a thermal plume, a hot spot.” Such domes are rare, he said.

“I refer to the Adirondacks as young mountains from old rocks,” Isachsen said. That’s because the region’s complexly folded granite, gneiss, marble and quartzite--formed at high temperature and pressure 20 miles beneath an ancient terrain resembling present-day Tibet--are 1.1 billion years old.

Isachsen figures the ancient rocks were poked up by a hot finger as recently as 10 million to 15 million years ago.

“I got to wondering if they’re still coming up,” Isachsen said. There are some clues that they are, he said, such as the bubbly sulfur springs and geysers at Saratoga on the southern fringe of the Adirondacks, and fault lines around the perimeter of the range.

By comparing survey data taken between 1931 and 1974, Isachsen calculated that there had been an uplift of a millimeter a year. But those results have been questioned because of inaccuracies in traditional survey techniques.

If the mountains are growing a millimeter a year--scarcely the thickness of a dime--what difference does it make?

For one thing, there could be the potential for earthquakes. There have been several temblors above magnitude 5 around Blue Mountain Lake, at the center of the Adirondacks, over the years.

“It could also make the Adirondacks a candidate for geothermal exploration, should our national energy needs ever demand it,” Isachsen said.

“It comes down to basic scientific curiosity,” Tice said, rapping his hammer against the summit rock, dislodging orange chunks sparkling with black mica, feldspar, quartz and garnet.

“These are old, old rocks,” Tice said as he scooped the shards into his rucksack to analyze later in research he’s doing with his wife, a geologist.

“They should have been eroded down long ago. How did they get here? It’s just something you want to know.”