The Clints and Grikes of Devils River EarthCache
The Clints and Grikes of Devils River
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Terrain:
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Formation
Limestone is formed from the deposition of plant and animal remains (calcium carbonate) on a sea floor. As limestone is a sedimentary rock, it is laid down in layers, separated by bedding planes (horizontal layers of weakness). These bedding planes are caused by changes in deposition rates or by the content of the material being deposited.
Scouring
Glacial movement scoured the earth as it advanced and receded throughout the ages. The weight of this ice passing over the Limestone caused small fractures which followed the existing bedding planes. It also caused fractures in other lines of weakness called joints. These lines tend to run at 90 degree angles to those of bedding planes. Slightly acidic water, from dissolved carbon dioxide and decaying vegetation, eroded at those lines of weakness. As these fissures widened, soil from the top of the limestone platform would be washed down into these fissures and eventually carried downslope. Over time, "all" of the topsoil would vanish, uncovering the fractured Limestone bedrock. These fractured, sharp edged, Limestone blocks are called Clints and the deep vertical fissures (joints) around the Clints are called Grikes.
Runnels
Runnels are gutter-like channels eroded out of the surface of the Limestone and drain into Grikes. Runnels formed on steeply sloping Limestone are generally close together and parallel. Runnels which have formed on gently sloped Limestone appear more branched (dendritic).
Pits and Pans
Pits and pans are solution features that are found on the tops of Clints. They are formed by water and acids dissolving into the limestone itself. Pits are generally deep and free draining, while Pans are generally shallow and retain water.
Movement
Thermal expansion (ice wedging), root wedging and other factors now have entry points in which to enter the Limestone and, working in tandem, force these blocks to spread and separate. When the gravitational force acting upon these blocks exceeds the resistance force, slope failure (mass wasting) occurs.
Park in the lot at the campground office near the Rock Mill Information Marker. Walk between the old buildings keeping the old silo just to your left and you will find a trail leading to the coordinates. Please do not drive up the hill into the camping area itself. Once at the coordinates, enjoy the view and answer the following questions. Email your answers to the questions, to me, using the link in my profile only. If your answers are not recieved by me, your log will be deleted. Photos are accepted and appreciated as long as the answers are not pictured. You do not have to wait for confirmation from me before logging this cache as completed. Most of all……learn……and enjoy the view.
At each set of coordinates listed (4 total) you will see instances of Mass Wasting (Limestone block removal). Site #4 is more or less just for the fun of it and does not have to be visited. Head down stream (under the overpass) from #4 if you would like a better view at the flat unbroken Limestone bedrock, waterfall and pool.
1. What is the height of block (Clint) loss at coordinates #1, #2 and #3?
2. Are instances of Pits and pans visible at coordinates #1?
3. Are instances of Runnels visible at coordinates #2?
4. Are instances of Grikes visible at coordinates #3?
This Property has been placed on the
"National Register of Historic Places".
Additional Hints
(No hints available.)