Spring 2005

A Boon for Business: Incubator nurtures homegrown companies

Antibody Buildup: University lab explores Libby health issue

Space Man: New UM researcher probes the solar system for NASA

Core Issues: Flathead Lake research reveals secrets in sediment

Lords of the Prairie: Investigating the links among sage grouse, West Nile virus and energy development

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Core Issues
Flathead Lake research reveals secrets in sediment

Geologist Marc Hendrix and a core sample taken from the bottom of Flathead Lake

The roomful of floods nuts gathered at the annual meeting of the Ice Age Floods Institute barely blinks when geology Professor Marc Hendrix tells them western Montana is due for a major earthquake anytime now.

But when Hendrix says that Glacial Lake Missoula may not have been the primary source of water that created eastern Washington’s channeled scablands, the shock in the room is palpable.

Hendrix is giving the keynote lecture at the meeting of IAFI, a regional organization of geologists, professionals and armchair geology enthusiasts. The institute’s Glacial Lake Missoula Chapter is hosting the meeting in a St. Patrick Hospital conference room.

When Hendrix drops his bombshell — “There is little evidence linking Glacial Lake Missoula and the floods in eastern Washington” — the room seems to collectively gasp. You can feel the rising ire of these mostly male, mostly middle-aged and older attendees, some of whom have hung their careers and reputations on the belief that a gigantic lake in western Montana repeatedly filled and catastrophically drained, gouging a path across four states to the Pacific Ocean.

But Hendrix gently reminds the audience that the Glacial Lake Missoula story has to be grounded in scientific evidence. By the time the question-and-answer period rolls around, the atmosphere has settled into polite skepticism.

Hypotheses disillusionment is a common geological ailment. Back in the early 20th century, geologists all believed in uniformitarianism, the idea that landscapes are formed by slow processes. When J “no-period” Harlen Bretz, a University of Chicago geology professor, introduced the notion that massive floods had created the channeled scablands, his colleagues ridiculed him for about half a century before finally admitting he was right.

This 20-by-20-foot barge was used to sample the lake bottom.

Similarly, Hendrix’s work challenges some cherished notions — such as the water source issue and the idea that Glacial Lake Missoula drained repeatedly.

“Based on examinations of Glacial Lake Missoula sediments, there is little evidence supporting scores of catastrophic drainings,” Hendrix says. “People get attached to their theories. Some will say I’m off my rocker.”

Who’s correct? Only time — and more research — will tell. One of the great things about Glacial Lake Missoula is that so much remains to be discovered — enough to keep at least a few generations of students busy.

Since 2000 Hendrix has done research at Flathead Lake that ties into the Glacial Lake Missoula story. This work has resulted in three undergraduate projects, six master’s theses in various stages and two doctoral dissertations.

“[Students are] the ones doing the heavy lifting,” Hendrix says.

One Ph.D. student, Michael Sperazza, is wrapping up three years of work. “At this rate we could spend another seven to 10 years,” Sperazza says. “We’re just touching the surface.”

Hendrix, Minnesota doctoral student Mark Shapley and UM geology Professor Johnnie Moore prepare to lower their coring device into the lake.

Touching the surface, literally and figuratively. Hendrix’s research team members have focused on collecting and analyzing core samples of sediments from the bottom of Flathead Lake. Their longest core sample measures 11.5 meters — about 38 feet — which represents 14,000 years’ worth but only 10 percent of total sediments.

Hendrix, a sedimentary geologist, came to UM in 1994. Six years later, he was concluding research in central Asia and Mongolia when he became interested in data collected by a fellow professor in the 1970s and ’80s.

“Johnnie Moore came stumbling into my office with a giant box full of seismic reflection lines from Flathead Lake,” Hendrix says.

Armed with these subsurface images and a National Science Foundation grant to research the lake’s record of deglaciation and climate change, his crew rented a specialized 20-by-20-foot barge from the University of Minnesota. The barge featured a core barrel rigged with a cable-and-pulley system and 1,000 pounds of lead weight to force it into the lake bottom. The team collected core samples in 2000 and 2003.

The samples were labeled, segmented, refrigerated, shipped to Minnesota, X-rayed, photographed, sampled, sliced and returned to UM and put into cold storage at Fort Missoula. In the lab, Hendrix and his students set about analyzing the data and correlating it with the seismic lines and other existing materials. Then they could begin to draw some conclusions about what’s been happening in the area for the past 14,000 years. Layers, grain sizes, minerals — all have a story to tell.

“Sediments can tell you an awful lot about what the environment was like,” Hendrix says. “You can learn to read them like a book.”

Red dots indicate where Hendrix's team took core samples in Flathead Lake. The lines show where seismic reflection profiles were shot.

Flathead Lake, he explains, was right on the boundary of the Cordilleran Ice Sheet — the massive block of ice that covered most of British Columbia — at the end of the last ice age.

“It’s an ideal position to capture a record of glacial retreat and climate change from glacial to post-glacial,” he says.

Some of the more interesting things they found:

• Between about 14,000 and 13,000 years before present, smaller glacial lakes, like those in the Swan Valley and Tally Lake area, probably drained rapidly as their ice “plugs” were pulled. They left their evidence — larger grains — in sediment layers called “event beds,” and probably in the erratic boulders found just below Kerr Dam.

• Between about 9,000 and 7,600 years B.P., the lake appears to have dried considerably, possibly becoming a “closed” lake — one without an exit flow — for several hundred years. This coincides with evidence found across North America of a significant warming period.

• The eastern shore of Flathead Lake, at the base of the dramatic Mission Mountain Range, is bounded by a major earthquake fault. In fact, the fault is in large part what created the lake.

• Core samples and mapping done by another Ph.D. student, Michael Hofmann, reveal two geologically recent quakes of about 7.0 magnitude on the Richter Scale. The evidence confirms earlier discoveries made by the Bureau of Land Management that suggest the earthquakes occurred 15,000 and 7,700 years B.P.

This core sample from the lake shows an ash layer from a 13,000-year-old volcanic eruption in Washington state.

Since those two quakes were about 8,000 years apart, and the last one was about 8,000 years ago, Hendrix says we’re due for another one.

“Missoula has a significant earthquake risk,” he says. “There is a very high probability of a major quake at any time, geologically speaking.”

In terms of seismic activity, Montana, Hendrix explains, is second only to California. And since Flathead Lake is the largest freshwater body west of the Mississippi, a quake here could have additional consequences: “The seiching action could cause an inland tsunami,” he says.

Thinking twice about that lakefront property?

This summer, two students will begin mapping the Polson Moraine — the hill that is believed to have been the terminus of the Flathead lobe of the Cordilleran Ice Sheet.

Hendrix’s plans for the near future include submitting his results for publication in scientific journals and securing funding for a deeper set of core samples in Flathead Lake.

Stay tuned.

Rita Munzenrider, Director
University Relations
The University of Montana-Missoula
32 Campus Drive | Missoula, MT 59812
phone 406-243-2522 | fax 406-243-4520
© 2007 The University of Montana