River Rat researches canyon while running rapids
Maybe you've driven alongside the Green River as it flows through Desolation and Gray Canyons in Utah. The river and canyons create a majestic scene of the beauty found in nature, especially in the West. The tranquil river helped form towering sandstone cliffs, with the gorge as deep as the Grand Canyon in some places, and there is an abundance of wildlife in the area.
These characteristics help place Desolation and Gray Canyons among the most popular areas in the United States for river rafting. One thing rafters notice is the variety in the width of the canyons in different spots, and the difference in rock formations.
Paul Roberson wonders why and how the canyon's makeup became so varied, even in spots that are close together. He is working on a research project to help determine some of the factors that contribute to canyon size and makeup. Roberson, 23, is a senior majoring in geology at Utah State University.
In June 2000, he began working on a project to compare the strength of rock found in the canyons to the size of the canyons. According to Roberson, the idea is not very complicated.
"I'm using an engineering tool, a *Schmidt Hammer,' to measure rock-mass strength through the Desolation and Gray Canyons of the Green River in Utah," he said.
"I am comparing my rock strength calculations with canyon width and debris fan size. It's fairly basic, but no one has ever done it before," he added.
A debris fan is a spot where a river has carried sediment from a higher elevation and deposited it into one spot. The sediment can range from small pieces, like pebbles and clay, to massive boulders. These fans are part of what interests Roberson. These debris fans also make the rapids which are enjoyed by many river enthusiasts.
A Schmidt Hammer is a metal, spring-loaded device that is placed against the rock. A tube shoots out, and gives a reading of the strength of the rock. It is usually used in construction to measure the density of concrete. In this case, Roberson is using the tool to obtain quantified results of the rock strength in the bottom of canyons.
Roberson compares the reading from the *Schmidt Hammer' to other variables found in the rocks he measures, such as the width and amount of cracks in the rock, and whether water is flowing through the rock. These variables all add up to give each rock a number, which amounts to the relative strength of the rock.
The widths of the canyons and the fan sizes were already measured and shown on highly detailed Forest Service maps, leaving Roberson's calculations as an important piece of the puzzle.
Roberson obtained a University Research and Creative Opportunity grant to help him complete his project. The $500 grant helped to pay for the trips to the Canyons. The department of geology at Utah State University also matched that $500.
All of the field work is done on river trips, which last 10 days. Roberson has been on three of these trips.
During the trips, Roberson, along with other researchers, goes to four different sites along the Green River and takes rock density measurements at each site. Two of the sites are accessible by road and hiking, the others require some rafting.
The upper site is characterized by shale and thin sandstone. The second highest is made up of massive, cliff-forming sandstone. The third site down contains an abundance of mixed mudstone and limestone. The last and lowest reaching site contains cliff- forming sandstone, with small amounts of shale along the river bed.
These different rock types are the major contributing factor to producing such varied canyon sizes along the Green River. The stretch of river that makes up Desolation and Gray Canyons is about 84 miles long. The middle part of the canyon is the narrowest, which is also where the strongest rock is found.
Roberson completed the last of his research trips over spring break.
"The trips are definitely an enjoyable way to do research," Roberson said.
He added that there are fun rapids at times and the river is calm at other times.
The mosquitos are one downside and can be "really bad in the summer months," Roberson said.
Before he started the research, Roberson believed that the harder the rock is, the narrower the canyon. His study has supported his thesis, and is the first of its kind in Utah to actually quantify the results.
Roberson believes this knowledge and data will help scientists to better understand and predict river dynamics and their effects on wildlife habitat, river restoration and recreation management.
He also has some personal goals for the project.
"I hope it will help me get into graduate school," he said.
He is also receiving upper-division university credit for the project and a senior thesis and hopes to have his findings published. He has already had an abstract of his research published in the Geological Society of America.
"My end goal is to convert my thesis into a co-authored paper with my project advisor," Roberson added.
The research project, entitled *Rock Strength and Canyon Form', is supervised by Dr. Joel Pederson, an Associate Professor in the department of geology at Utah State University.
Pederson came up with the idea for Roberson's project when a master's student, Carrie Elliott, was working on a project finding out about the Green River's geomorphology and its relationship to fish habitat. Pederson thought that it would be useful to have someone actually quantify data about the rock in the canyons surrounding the Green River.
Roberson was a perfect fit.
"Paul is a little bit of a river rat," Pederson said.
He added that Roberson needed a senior thesis and had performed well in one of Pederson's graduate level courses. Roberson had the skills and interest for the project, and Pederson felt that the research would be important.
Pederson added that this is the first step in a continuous research project. Roberson, Elliott, Pederson and Dr. Jack Schmidt are all part of the research, which will continue after the students leave the university.
"These are the first steps in continuing research about the canyons and the overall geomorphology surrounding the Green River," Pederson said.
He added that the research will be used for more practical purposes in a few years, after more research is done and more data organized. He believes that this research will become an important tool for helping to understand and predict the makeup of Desolation and Gray Canyons.