Member: Colorado Springs Mineralogical Society Pebble Pups
Introduction: My family went on a road trip this summer to South Dakota and ended up at Badlands National Park. We camped at the Cedar Pass Campground, hiked the Saddle Pass Trail and had two days to explore, which wasn’t enough but was still very fun. One day we did the GPS Adventure Tour. On this tour we counted cliff swallow nests on the Notch Trail, learned about the “slump” on the Cliff Shelf Nature Trail (a slump occurs when a layer is squished down due to the force from a rock fall), visited the Saber Site and Fossil Lab where we saw our friend Matt’s picture on their fossil finds board, and finally we completed the erosion study which was the most difficult and interesting task.
Overview. Photo by
One of the things scientists in the park are studying is the rate of erosion. Erosion occurs when soil and rock are pushed off the surface by wind or water. I thought people climbing on the buttes would also cause erosion but according to the Ranger at the night program I attended at the amphitheater human impact is minimal. That was great news for me because I was allowed to climb all over. I still think the buttes most people climb are probably shrinking fastest but my guess is most of the park remains untouched.
For the Erosion Study we had to locate three markers by GPS near the Visitor Center and do some measuring, calculations, and guessing. I found all the markers and measured from the base of the rod where it went into the butte, to the very top of the rod curve. My mom recorded the numbers for me and helped with the calculations so the Data Table is a clean copy of my results. It turns out we visited the park almost two years after the markers were placed, which made our calculations easier since we cut the erosion rate in half to determine erosion in inches/year.
Before we did the calculations we made a hypothesis on what we thought would erode faster. I guessed the marker on the bottom of the butte, erosion marker 1, would have the highest rate of erosion because the rain would rush down and push more of it away. My mom thought erosion marker 2, on the top of a mound, would erode the fastest because it had greater exposure to wind and rain.
Art by Jack Shimon|
My conclusion is that the white layer is softer and consequently erodes faster than the red fossilized paleosol. It would be very interesting to return in one or two years and see if my calculated erosions rates still apply. In the questions to discuss at the bottom of the data form it asks how long would it take for the butte with erosion marker 1 to disappear if it was 30 feet tall? My mom helped me convert that to inches and then we calculated it would take 600 years! That seems like a really long time until I thought about question 2. If the park starts to get more rain it will erode faster. Rain is a good thing, but maybe not for the park. I definitely want to go back to Badlands National Park to learn more about the geology.
Erosion Marker 1. Elevation 2449 ft.
To the left of Jack, placed about elbow height.Photo by Jeff Shimon
Erosion Marker 2 Elevation 2464 feet. On top of a mound.
Reddish rock paleosol is the top constituent although it is
well worn down close to the white layer Photo by Jeff Shimon.
Erosion marker 3. Elevation 2465 feet. Jack with the ruler.
Measurements were taken from ground level
to the top of the curved part of the marker. Photo by Jeff Shimon.
Erosion marker 3 in the foreground of the butte.Photo by Jeff Shimon.