~~You are looking for a rock bluff with a nice overhang (rock house). You will know you are at the correct area when you see on the walls of the rock house here some unsightly green and yellow graffiti painted on the rocks.
Blue Creek is one of my favorite places on the Black Warrior River. I have lots of great memories of camping and playing at Blue Creek Park over the years. I have climbed and repelled the cliffs here at this Earthcache site. The views here from above Blue Creek and the Black Warrior River are beautiful. I hope you will take the time while here to just sit, relax, and take in the beauty of this spot.
As you look at the rock face here you will see the slightly darker crumbly shale rock laying underneath the lighter gray colored and harder sandstone. Both of these rock types are from the Pennsylvanian Period and are part of the Pottsville Formation and have an age of around 307 to 315 million years. The boundry where the shale and sandstone rock layers meet is called an Unconformity. An Unconformity is a break in Geologic Time. In any given area, material is either being deposited at a site or it is being eroded away. Rocks and material that are exposed to weathering are eroded away and with the erosion the geologic record is being erased. An Unconformity occurs when the geologic record has been erased for a period of time. The the shale rocks here were formed when very fine grained material was deposited in an area covered with water that had little current. You can feel the smoothness and fineness of the material that composes the shale. At some time in the geologic past, the fine shale material ceased to be deposited here and the environment changed as some of the material began to be eroded away. We do not how much material was removed. That is the unknown aspect of an.Unconformity..
At some later point in time the environment here changed again and then larger sized material like sand began to be deposited here. This material would be what composed the sandstone you see here. Like the shale layers, the sand was deposited in a water environment such as a shallow sea along or near the shoreline, in a large river delta or in a large meandering river bed. By looking at the sand deposits here, we know that the water had a fair amount of current by the presence of SWIRL EDDIES in the rock. The moving water was swirling in small eddies and these eddies caused the sand material to be deposited in the same way as the water was swirling. You can look at the sandstone layers here and clearly see the SWIRL EDDY deposits in the sandstone. They are the oval shapes in the sandstone.
Loggng Requirements:
Please answer the following questions and email me the answers. All FIND logs that are not accompanied by correct answers will be deleted.
1. What is an Unconformity?
2. How high is the Unconformity from the floor of the rock house?
3. How many Swirl Eddies do you see in the sandstone in the rockface of the rock house?
4. What is the average width of the Swirl Eddies?
5. Why do you think there are no Swirl Eddies in the Shale layers?
7. Optional Picture - Take a pic of yourself and the beautiful Blue Creek below. DO NOT TAKE A PIC OF THE GRAFFITI on the ROCKFACE here (I would hate to have to delete your pic)
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If you enjoyed this earthcache and the beautiful view, give the cache a Favorite Point.