What is Limestone?
Limestone is an organic, sedimentary rock. This means it was formed from the remains of tiny shells and micro-skeletons deposited on the sea bed. They were compressed to form solid rock. Limestone is made up of calcium carbonate and reacts with diluted hydrochloric acid. Limestone is formed in layers - called bedding planes. These bedding planes contain vertical cracks called joints. Joints and bedding planes make the rock permeable.
Erosion of Limestone
Weathering is the breakdown of rock by physical, chemical or biological processes. Limestone areas are weathered when rainwater, which contains a weak carbonic acid, reacts with limestone. When it rains limestone is dissolved. Rainwater erodes the joints and bedding planes. This erosion then creates krasts in the wall and causing it to be very weak holding up the block. The block falls and leaves a cool area to explore.
Limestone Feature
Located within Rockwood Conservation Area, the posted coordinates will bring you to an excellent example of Limestone cliffs that tower high above you. Here you can find various prominent examples of how these limestone features have been affected by erosion.
A very large chunk of the cliff has fallen off of the main cliff. Based on the indents and outdents of the cliff and that of the fallen chunk of rock, can you tell with ease on where it used to be attached? It's like putting together a giant 3D puzzle.
Tasks and Logging Requirements
1) How far has the chunk of rock fallen from the cliff. Measure the closest distance which may not necessarily be at ground level.
2) Examine the rock cliff. Are there any other signs that another chunk of rock will break loose from the cliff? If so, where is it and what would be the approximate measurements of the chunk of rock that may fall next. How many times smaller (or larger) would this chunk of rock be that the very large one mentioned above in #1 that has already fallen?
3) You will also find another example of erosion here that has formed a unique and interesting feature. Hint: There is a national park on Moab, Utah named after this type of feature. What is the type of feature and how tall and wide is it.
Email me the answers to the above questions and then go ahead and log this earthcache. Feel free to post pictures too.
** Please note that there is a fee to enter Rockwood Conservation Area. See additional waypoints for entrance location.