Welcome to the East Rim Overlook in Big South Fork National River & Recreation Area. This earthcache is handicapped accessible and open to the public year-round.
The River Gorge of the Big South Fork of the Cumberland River
The Big South Fork's most prominent feature is the river gorge cutting through the softer Mississippian age rock beneath the hard Pennsylvanian capstone of the Cumberland Plateau. Water is the most influential agent of geologic change in the Big South Fork region. Over time water action has left many unique and amazing geologic features ranging from the river gorge with its magnificent bluffs to the natural arches and unusual hoodoos.[1]
Due to the substantial amount of annual rainfall of the region and the action of the Cumberland River and surrounding tributaries the water acts to erode the softer Mississippian rock composed of limestone, shale, and calcareous sandstone from beneath the much harder and erosion resistant capstone composed of Pennsylvanian sandstone. Flowing water hollows out the softer layers beneath and forms waterfalls and gorges. Where there is hard capstone intact, arches can form creating natural bridges across streams or dry ravines. Direct erosion widens a joint and forms a cavity below the more resilient rock thus creating a void between the hard capstone and the area below. As result, water eroded arches are formed in the Big South Fork. Hoodoos are a rare but intriguing feature occurring in the Big South Fork. These hoodoos form in a similar manner to those found in the western United States. Where tough capstone still exists on the side of a hill for instance, it prevents the erosion of the softer material below. The result is a naturally formed erect columnar rock where once was located a hill.[2]
References:
[1] Russ Manning. (1994). "Exploring the Big South Fork." Norris: Mountain Laural Place.
[2] Russ Manning. (1999). "The Historic Cumberland Plateau." Knoxville: The University of Tennessee Press.
To get credit for this Earthcache you must complete the following requirements.
PLEASE SEND A Geocaching message TO Life-Long-Ridger starting with BSF: East Rim Overlook AND ANSWER THE FOLLOWING:
1) Let's find out how much erosion has occurred from the Eastern Rim to the river below. How far above the Cumberland River are you at the posted coordinates for the overlook? (I will provide some additional information. The elevation at the Cumberland River below is 1,004 ft above sea level. Use an altimeter on your phone (There are many free apps available for your phone that will measure your current altitude) or GPS unit to find your current elevation and then subtract 1,004.) You can send me your best guess based on your observations while at the overlook if you cannot get your altimeter app to work on your phone.
2) Look directly below you and observe the rock that the overlook deck is built upon. Based on the information provided in this earthcache description, what type of rock do you think this is?
3) Based on your observation, would you consider this a hardened type of rock or a softer type that is easily able to succomb to erosion?
4)Post a photo of you or your group with the river gorge behind you or just a nice shot of the river gorge itself with a trackable item or piece of paper with your caching name as proof of your visit.