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Rocks and Rain

First-year students see effects of flood firsthand

“Year One, Block One, Day One of class at Colorado College, and we are already getting our hands dirty,” Isabelle Febvre ’17 and Emelie Frojen ’17 wrote about their First Year Experience geology course.  “Our professor, Christine Siddoway, greeted us first-year students eagerly and told us to get our sun hats and tennis shoes, and to get ready for an active field afternoon at our study site at The Fan.”

Little did they know that The Fan, a formation at the base of Cheyenne Mountain, on the south side of Colorado Springs, would a week later become an active, and muddy, laboratory to measure the impact of the rains that pounded Colorado recently.

student holding a rain gaugeThe 16 students in Siddoway’s geology class spent the first two days of class exploring, observing, and collecting data in The Fan.  “You can think of this as a paper fan, the handle would be the main stream and the bends in the body its channels where the sediment and water runoff of the Cheyenne Mountain stream is deposited,” wrote students Dana Cronin ’17 and Carina Rodriguez ’17.

Febvre and Frojen described their work on The Fan during the first two days of class, when Siddoway asked them to try to figure out what had happened in the area over time, and why:

The afternoon and the following day consisted of exploration, observation, data collection, and lots of sun blocking. Trees at the base of The Fan seemed buried under layers of cobble as evident by the lack of showing root. A few broken branches scattered around the base of The Fan were stripped of bark and pointing downward. Mini channels, no more than a few inches in width and depth, ran down the inside of the structure. Further up The Fan, the walls grew taller, reaching up over our heads in some areas and exposing soil, rock, and roots. The ravine curved in some areas and sloped steep and straight in others. The dimensions, rock sizes, and mini channels all varied, but we diagnosed the color and type of rock to be consistent. By the end of those two days, we'd developed a few different comprehensive hypotheses that weren't too far off!

Torrential rainfall had created dynamic channels of all sizes that eventually open and pour into the shallow and wide base of the alluvial fan. The floods rapidly carved out the streams and channels, deposited gravel at the base of The Fan and around the pines, and eroded the rounded rocks. Maybe we wouldn’t be so novice for long!

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Just a little over a week after our investigation at The Fan, Colorado Springs residents woke up to backyards, homes, and roads that had been flooded and closed during early hours of the morning. Creeks almost instantly turned into rivers that were roaring downstream, moving boulders, and overflowing into surrounding communities. Our plans for the class that day rapidly changed! Our original plan of an all-day field trip to Denver and Golden to perform fieldwork and attend a lecture given by our professor at the Colorado School of Mines was canceled due to the severe weather. When the class met later on that morning, we unanimously voted to return to The Fan to see our hypotheses in action!

Back into the two James Bond vans (“two glossy, white vans with tinted windows that looked like they were built to endure James Bond missions”) we eagerly headed back to our study site. By the time we arrived that morning the gushing water was already gone, but it did leave spectacular evidence showing what occurred earlier on the morning of Sept. 12. Carved out walls and channels, eroded and tumbled rock, and newly exposed roots were all over The Fan. Travelling up The Fan we got our hands dirty once again while experimenting with clay/silt and discovering sediment transportation. Further up the channel we were stunned at how deep the study site had gotten.

Student Greg Sayles ’17 stood in the channel, with Rayna Nelson ’17 standing on the ground above him, giving perspective to how deep the channel had become with the recent rains.Student Greg Sayles ’17 stood in the channel, with Rayna Nelson ’17 standing on the ground above him, giving perspective to how deep the channel had become with the recent rains.

Like the students, Siddoway was thrilled that they could all respond so quickly to the torrential rains and learn from it, safely.

The Fan is “a safe, small-scale, natural system that allows direct student learning opportunity,” Siddoway said.  The site “will enhance the students’ understanding of, and potential future contribution to, high-risk areas such as drainages flowing out of Waldo Canyon burn area and Black Forest,” she added.

“In class, we are calculating — through use of field GPS instruments and GIS computations back in the Keck Geospatial Commons — how much granite-gravel from the slopes of Cheyenne Mountain was transported downslope in this historic high-precipitation event,” Siddoway said.

In fact, even Siddoway’s own home became a study site.  She lives near a creek not far from Cheyenne Mountain, and the rains turned it from a quiet stream to something quite different.  Febvre and Frojen take up the story again:

We returned to our professor’s house to view her creek-turned-river. The change from the first time we saw her backyard was immense. Large rapids were moving huge boulders, and all of this occurring right before our eyes in her backyard! Christine had a rain gauge that increased from less than one inch to seven inches overnight! We were able to witness first hand the study of sediment transportation in high-precipitation events.

The students learned from a short lecture and studied mineral deposits at another site, then realized that they were still so excited about the experience that they didn’t want to go their separate ways.

Again, Febvre and Frojen:

All of our excitement poured over into the night, so we took Christine up on her offer to take the 16 of us to a rap/ written word performance by a fellow Colorado College professor!

The rain continued to pour throughout the night, and after the performance, we were all thinking the same thing: The Fan. Disregarding our original plan to return to campus we headed to see our site in action at 9:30 at night!

Soaking wet with smiles on our faces, the entire class was in awe of this geological process. Water was transporting sediment everywhere and we were able to witness it.

The Fan remained a safe site to follow the action, allowing Siddoway and the students to observe a big event at a small, accessible natural laboratory.

The rains broke records in Colorado, according to students Ximena Buller ’17 and Ryan Kwan ’17, who wrote:

In Colorado Springs, a record of at least 7 inches of rain was collected in 24 hours whereas in the past, the highest amount of rain Colorado Springs area collected in the month of September was 5.91 inches in 2011. Such high amount of rain caused rivers and creeks in Colorado Springs that are normally dry or have a relatively low flow rate to flood over bridges and the creeks became roaring rivers.

For instance, Monument Creek at Bijou Street which normally has an average discharge of 20 cubic feet per second reached over 3000 cubic feet per second during the recent floods

Febvre and Frojen summed up the experience:

The first two weeks of the geology FYE showed us first-year students what "building on the block" truly means.