Rocking and hiking
Geology hike on Back 40 trails draws more than 100
A long line of attendees, including children, adults of a wide range of ages — and plenty of dogs — showed up for a 1.75mile hike on the Back 40 trails led by University of Arkansas geology instructor Henry Turner.
The sunny Saturday, April 1, made for a great hike.
Turner, who has taught at the University since 2008, holds a bachelor’s degree in geological sciences, a master’s in geology and a doctorate in space and planetary sciences.
He led hikers down the steep trail toward the edge of Lake Ann to examine an outcrop and explain it in depth.
Arkansas, he said, has interesting geology.
“The Ozark Plateau,” Turner said, “is the result of what we call a structural uplift, a structural dome. We have these steep valleys where rivers have eroded, sort of cut into the terrain.”
That, he said, explains the region’s rough topography.
Upon reaching the outcrop, Turner waited for the long line of hikers — estimated at 100 individuals — to reach the site before he started explaining what everyone was looking at.
“We believe that these formed in ancient oceans,” he said.
This formation was largely sedimentary rock, he said, layers forming, then the pressure from above compacted the sand and silt, while water flowing through it helped to create a sort of cement that helped it solidify.
Some was also chert, he said, which was essentially compressed skeletal remains of tiny organisms.
Over time that ocean receded. In more recent times, he said, it has been shaped by erosion.
“We’ve got an overhang,” he said, “so you can see there’s more erosion further down.”
This, he said, is the result of flowing waters carrying more material away.
Near the bottom, he said, is a great deal of loose shale. The loose stones, he said, are referred to as “float” in geological terms.
“You have to be careful when you’re looking at float,” he said. “Somebody could have put that there just to trick you.”
While he didn’t think it prudent to disrupt this feature, he said, geologists will often break rocks open to get a better look at them. This helps to see a raw surface, he said, which can be far different from the rock’s weathered surface.
Another tool for identifying stones, he said, is the Mohs Hardness Scale, which assigns a number from 1 to 10, ranking how hard an object is. So if something will scratch his steel hammer, he said, he knows it is harder than the 5.5 assigned to steel.
One attendee was very impressed. Michael McCauley showed up with his wife, Julie McCauley, and three children, Morgan McCauley, 13, Leah McCauley, 10, and Kyle McCauley, 6.
His oldest son, Morgan, is extremely interested in sciences, spends a lot of time reading and has plenty of questions, Michael McCauley said.
“I like it, my son’s very inquisitive,” he said. “They like to learn.”
Another hiker, Alli Brooks, showed up with her mother, Carolyn Brooks, and sister, Ashley Brooks, as well as Ashley’s dog, Madiba.
“It was great,” Alli Brooks said. “It was nice to get out in the sun, spend some time with the family.”
Turner said he was glad to see young people with questions, in addition to the massive turnout.
“I was surprised by how many people showed up,” he said. “It was a good crowd.”
Bella Vista trails coordinator Kay Curry said that she was shocked by the turnout. She expected around 20 people to show up, she said, based on interest shown in social media.
But she was happy with how the event turned out, she said. She intends to set up more guided hikes in the future.