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Set in stone
Posted: Sunday, Sep 25, 2005 - 10:39:27 am MDT
By WILLIAM L. SPENCE
The Daily Inter Lake
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| ReBecca Hunt sits on top of the Snowslip Formation near Goat Lick in Glacier National Park. The red and brown wavy layers in the rock are fossil stromatolites, formed by photosynthetic bacteria that grew in a shallow sea about 1.45 billion years ago. Hunt spent four months in Glacier this summer, summarizing the park's extensive fossil resources. Chris Jordan/Daily Inter Lake |
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Glacier National Park is fertile ground for fossils Glacier National Park is world-famous for its gorgeous scenery, glacial landscapes and abundant wildlife.What many visitors don't realize, though, is that it's equally rich in fossil resources. Paleontological research in the park began almost a century ago. Since then, fossils have been discovered in about 80 percent of the rock formations located there. |
And if more recent research holds true, a handful of fossils found a quarter-century ago in the Many Glacier and Two Medicine valleys could represent the earliest evidence of multicellular life.
"Glacier has an enormous number of fossils. Of the 24 rock formations in the park, 19 have fossils -- something most of the visitors I talked with had no idea about," said ReBecca Hunt, a research intern and paleontologist who spent four months working in the park this summer.
Hunt received her master's degree in geology from Texas Tech University in May. She came to Glacier as part of the
Geological Society of America's GeoCorps America program, which provides job opportunities for recent grads in national parks and national forests around the country.
"I love Glacier," she said. "To me, if there's a heaven on earth, this is it. So when I heard there was an opportunity to do paleontology in Glacier, I thought nothing could be better. I applied for [the position] the minute I saw it."
Hunt grew up in Oklahoma and Arkansas, but she'd visited Glacier several times before during road trips with her mother. Her aunt and uncle, Terri and Jon Hunt, also live in Kalispell.
She first became interested in paleontology when she was 13, after reading a dinosaur book written by Jack Horner, the current curator of paleontology at the Museum of the Rockies in Bozeman.
"It sounded like the funnest job ever," Hunt said. "You get to be outside all summer, and then spend the winter indoors working on what you found. It's like being Indiana Jones, but you look at stuff that's a lot older and cooler. It seemed like an adventurous, exciting job."
Her responsibilities here were a little more mundane, though. She had to produce a report summarizing Glacier's paleontological history and resources, and recommend ways for the park's interpretive staff to include fossils in their public education efforts.
The job involved as much reading and writing as field work.
"It was a very intensive summer as far as reading," Hunt said. "I'd read about the different fossils found here and then go out and try to relocate the sites. It was a good way to learn about the different forms and about the rock types they appear in."
Most bedrock in Glacier is part of the Belt Supergroup, a series of primarily limestone, mudstone and siltstone sedimentary formations that were laid down about 1.45 billion years ago.
At the time, a massive rift had begun tearing the continent apart.
Many geologists believe the rift started somewhere near what is now northeastern Washington. Over a period of about 70 million years, it opened a deep hole in the earth, allowing more than 55,000 feet of Belt sediment to accumulate.
By comparison, the average depth of the Pacific Ocean is about 13,000 feet.
Some of the sediment was washed in by what researchers estimate was a continental-scale river system, similar to the Mississippi River today. Minerals also precipitated out of the water, forming the Belt limestone and dolomite.
Geologists still disagree about whether this "Belt Sea" was just a huge lake, or whether it was at least periodically connected to the ocean.
The critical point for paleontologists, however, is that water was plentiful. That's why Glacier National Park is awash in fossils today.
Most of the park fossils are stromatolites -- mounds of photosynthetic bacteria that grow under water. Their golden age came during the Proterozoic Era, from about 2.5 billion to 540 million years ago, but modern, living stromatolites can still be found in a few locations.
"They're one of the simplest and oldest life forms on the planet," Hunt said. "They created Earth's oxygen atmosphere and set the stage for everything that followed. It's amazing: They used to be in the ocean, and now they're thousands of feet in the air."
Fossil stromatolites in Glacier come in several shapes, including domal, hemispherical, conical and branching.
"That's the amazing thing about the fossils in the park," Hunt said. "There's such a variety."
Viewed from the side, stromatolites look something like a pastry, with numerous thin, curved layers of sediments stacked atop each other like sheets of phyllo dough. Sliced through the top, they look like tree rings or a bull's-eye.
The layers form when tiny grains of rock adhere to the sticky bacteria mats. Bacteria then grows up through the grains, seeking sunlight, allowing the next layer of sediment to accumulate.
Over time, stromatolites can take on huge dimensions. While they often appear as small mounds or cones, ranging from one to a few feet in size, there's also a massive reef complex that can be mapped throughout the park.
Known as the "conophyton zone," this reef covers hundreds of thousands of acres, stretching from Kintla Lake on the north to the Two Medicine Valley and Running Rabbit Mountain on the south. In some places, it's more than a hundred feet thick.
Stromatolites in Glacier typically range in color from tan or brown to battleship gray, depending on what type of rocks and minerals were present when they were alive.
Hunt's favorites are the stromatolites of the Snowslip rock formation, which have layers of red or green and white sediments.
"They're very pretty, and you can tell so much from that formation," she said. "Sometimes you can see ancient wave events, where the mounds got trashed and then redeposited. And they're almost always in beautiful locations, with incredible views. I saw some [above the Highline Trail] near the Grinnell Glacier Overlook. It was a perfect day."
Hunt stressed that taking fossils -- or even rocks -- from the park is illegal.
"I really want people to know about the fossils in the park, but I also want them to appreciate and preserve them," she said. "So much can be learned from fossils, but nobody learns anything when they're sitting in someone's home."
Evidence of that came just a few years ago, when researchers finally examined some unusual fossils that were collected in the Many Glacier and Two Medicine valleys in the late 1970s.
Often described as a "string of beads," the fossils look like lines of small, regularly spaced circles. In some samples, connecting strands can be seen linking the circles; "holdfasts" that may have anchored the strings to the seafloor have also been detected.
When paleontologist Robert Horodyski first discovered these fossils, he wasn't convinced of their biological origin. He described them as "pseudo-fossils" or "enigmatic bedding-plane markings."
However, identical fossils have since been found in Western Australia, lending credence to their organic nature.
The fossils themselves haven't been dated, but the rock formation they were located in is between 1.47 and 1.45 billion years old. Horodyski collected about 20 samples, two of which are in the park's collection. The remainder were sent to the Smithsonian Institution.
In 2000, two of Horodyski's colleagues examined the Smithsonian samples and suggested that the string of beads represent "the earliest tissue-grade colonial eukaryotes," or the earliest multicellular life.
"There's still work being done on this, so it could change, but it's a very significant finding," Hunt said. "It pushes back the date for multicellular life on the planet [by about 250 million years]."
Given discoveries such as this, Hunt is enthusiastic about future research opportunities in Glacier. Her stint in the park ends on Oct. 1, but she hopes to encourage other paleontologists to visit.
"Who knows what new things can be found," she said. "More research could be done on stromatolites, on their mode of life and ecology. And the Cretaceous [dinosaur-age] rocks in the park are virtually untouched. Nothing has been done on them since the '70s, even though dinosaurs have been found just outside the park, on the Blackfeet Reservation. They're a book waiting to be opened."
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The Daily Inter Lake
727 East Idaho Street / Kalispell, Montana 59901 / 406-755-7000
