The first ever geologic maps of the Missouri River Valley have been completed thanks to an ongoing project by the Department of Geociences at Southeast Missouri State University.
The project, a pilot study of the Missouri Valley alluvial fill (deposits of clay, sand silt, gravel or other matter deposited by running water) was proposed by Dr. John Holbrook, professor of geology at the University, and is funded by a competitive grant from the Educational Component of the National Cooperative Geologic Mapping Program and the United States Geological Survey.
The project began in 2001, and Holbrook has reapplied for the grant each subsequent year. Another application has just been sent which, if approved, would allow him and his teams to continue mapping for another year.
“The gist is, as part of funding the research, they want to see that people are producing geologic maps, and they want those as evidence that students are being trained to do the mapping,” Holbrook said.
It produces both actual physical maps and “people who know how to make maps,” he said.
Funding for the project is based on scientific merit and societal need. According to Holbrook, it is critical to have accurate data on the deposits of the Missouri River Valley, due to its location between the state’s two largest urban areas.
“This is one of the biggest rivers in the world and no one had ever done any mapping of the alluvium,” he said. “We’re actually growing cities into these floodplain areas, and all the foundation support, groundwater and wildlife habitat are dictated by the materials that fill the valley.”
The maps are divided into quadrangles, each of which could cover a large dining room table. When combined, they will show where the river has been throughout time. Certain to be important resources for urban planners, developers, farmers and builders, the geologic maps also will be useful to historians, who, for example, can obtain through them their first glimpses of what the Missouri River would have looked like before Lewis and Clark encountered it.
Working in two-person teams, the students create hypotheses about geologic features and, armed with drill rods and a truck-mounted hydraulic rig, set off into the river valley to test them. Team members work on independent assignments, yet cooperate and assist one another.
“I like to team up a grad student and an undergrad,” Holbrook said. “Each one has their own map, but they work together in the field. They get the benefit of each others’ help.”
Nicolette Tanksley, a senior from Cape Girardeau, and Chima Nzewunwah, a graduate student from Lagos, Nigeria, composed the team that participated in the mapping project since it began.
“Nicolette and Chima were my first team,” Holbrook said. “They started in 2001 and are just finishing. I have two teams of two who continue this work, and are mapping four additional quadrangles in the valley adjacent to those Nicolette and Chima mapped.”
With Nzewunwah mapping roughly 32 miles of the floodplain, and Tanksley mapping roughly 38, the two produced the first ever detailed maps of floodplain sediments in the Missouri River Valley, and, henceforth, geologists conducting similar research in the area must adopt their measuring tactics.
“In order to keep things standard, geologists try to use the same units as existing studies,” Tanksley said. “The cool thing about this particular project is that we have set the standard for map units on the Missouri River Valley.”
Geologic map making is a complex process that begins with scientists examining existing data. Research pairs had to do considerable work before ever packing up their drills and heading for the field.
“We got a whole bunch of aerial photographs and satellite images,” Nzewunwah said. “Sometimes they give you very precise information, and sometimes they don’t, but fluvial systems have a unique way of laying down deposits in a floodplain. If you look at an aerial photograph and you can make out the geometry of the river, you can form a hypothesis of what you should find. You make that hypothesis, then you test it.”
Tanksley said if the hypothesis is correct, it must be drawn onto the map.
“If it’s not, you go back and get a new hypothesis,” she said. “You just keep doing that until you have every channel and sandbar you can find. Then you go home and put it in the computer.”
Nzewunwah described the process as very complex.
“The Missouri River is very dynamic,” he said. “Sometimes when you expect to find a channel, you find a point bar. And sometimes you find a point bar on top of a channel.”
The area in which Tanksley and Nzewunwah drilled is located in rural central Missouri. Staying five days a week in nearby Marshall, Mo., during the summer and making frequent trips to the field during the winter, the team encountered numerous challenges.
“We drilled in all types of weather,” Nzewunwah said. “We drilled in the rain ᾰ as long as there’s no lightning, you’re good. You don’t want to be raising a big metal rod in lightning. And in the heat of summer, in the dead of winter with frozen hands … oh, man, it was miserable. The summer was all right, but the winter was terrible. I walked on a frozen river; there is nothing like that in Nigeria. I had a disposable camera ᾰ I had to seize the moment.”
Despite difficult physical labor, tedious hours of traveling and often less than ideal weather conditions, Nzewunwah and Tanksley agreed no portion of the geologic mapping project was more grueling than compiling the collected data and analyzing it on computer.
“There were a lot of annoying, frustrating parts,” Nzewunwah said. “There was this one hole we drilled for seven hours. We were standing constantly, lifting heavy rods. But to me, the most difficult part was spent at the computer, staying in the lab until two or three o’clock in the morning, trying to draw it up.”
Tanksley said this component of the research ᾰ the going back and looking through the detailed records ᾰ took longer than collecting the samples.
“You log them in 10-centimeter increments. That’s a lot of data.”
Ten centimeters on a table-sized parchment, bought by hours of driving, drilling and drawing, bring a bit of scale to this mapping endeavor.