Principle of Original Horizontality Along Hwy 412 - Earthcache
This cache is located along Hwy 412. The Limestone Wall of interest is located on the south side of the highway. You can park off the Highway along either the West-Bound or East-Bound lanes of Highway 412, I think stopping along the east-bound side of the road works best as this position puts you closer to the wall and give you a better overall view. There is plenty of room to safely park off the roadway here along the highway.
This is an Earthcache and as such is a kind of virtual cache in that there is no physical container to find and log to sign. You must answer the questions below and then email or message the correct answers to Papa Bear 204. Any “Found Log” that is not accompanied with an email with the answers will regrettably be deleted. I strongly suggest that you send your answers as you are logging this find. Please take care of this task within 5 days of logging a find.
Tools Needed: It might help to have a straight edge tool such as a straight aluminum hiking pole to hold up at arm’s length, horizontal and parallel to the rock layers. This will help in answering the questions below. A protractor might also be useful here in determining the angle of change.
Please read the Educational Reading before attempting to answer the questions.
Questions for Logging Credit:
1. The sediment that formed these limestone rock layers here were originally deposited horizontally. What has happened to the rock layers in the rock wall on the south side of the road cut of the highway here.
2. Estimate the angle of change in the rock layers from the far right and far left side of the rock wall. A protractor will be helpful here. (Remember that these rock layers were once straight and horizontal).
3. What Geology Principle best describes how the material that formed these rocks were originally deposited?
4. From your answer in questions #1 and #3, what has happened to these rocks since they were originally formed? Explain how this might have happened.
5. Take and post a pic of the Limestone rock wall here. Optional: Include yourself and your group in the picture.
If you enjoyed your stop here at this Earthcache, please post a Favorite Point. The Earthcache will appreciate this gestor.
Educational Reading:
In geology, The Principle of Original Horizontality states that layers of sediment are originally deposited horizontally under the action of gravity. The principle is important to the analysis of folded and tilted strata that we see on the surface of the earth’s crust and this helps us to understand what has happened to these layers of rocks here in Arkansas. The earth’s great dynamic internal forces and resulting plate tectonics cause movement and collisions of large plates of the Earth's crust. The collisions of these plates result in rock strata being folded, tilted, broken, uplifted, and subducted. The rocks that you see here were originally formed from horizontal deposits of fine fragments of marine organism and calcium carbonate on the seafloor. Those deposits of marine organisms and calcium carbonate formed the Limestone that you see here. The Earth’s dynamic tectonic forces most likely resulted in COMPRESSIONAL FORCE being focused here to alter these layers of Limestone to their present position. That is, a pushing force from the east and a pushing force from the west acted on this area and caused these rocks layers to be altered from their original horizontal deposition. These rocks were at some time in the distant past horizontally laying Limestone. The rock layers were pushed together and folded upward. Erosion is now gradually causing the brittle Limestone here to break apart and gravity is working to deposit the Limestone fragments again horizontally somewhere else downslope of here.
Sources:
https://en.wikipedia.org/wiki/Principle_of_original_horizontality http://www.thisoldearth.net/Geology_Online-1_Subchapters.cfm?Chapter=4&Row=2
En.wikipedia.org/wiki/Limestone
Additional Hints – bring a yard stick or hiking stick plus a protractor