Cowards Hollow Natural Area has a number of significant geological features, as well as natural plant communities.
NOTICE! There have been reports of feral pig sightings in the area. Please stay aware of your surroundings and exercise caution with your dogs while in the area.
To claim this EarthCache, please answer the following question.
Make your way across the stream at the top of the falls and down to the stream bed below the falls. Here you can observe the large rock shelter on the south side of the stream. Compare the following illustrations with the large rock shelter and determine which of them you believe contributed to this formation. Explain why you believe this to be the primary force behind the formation of this rock shelter.
Rockshelter formation by frost weathering occurs when water is frozen within cracks in the rock and breaks or chips off pieces of the rock. It is especially associated with alpine, periglacial, subpolar maritime and polar climates but occurs wherever freeze-thaw cycles are present.
Rock shelter formation by river erosion occurs when a stream bed encounters a softer stone layer underlying a harder stone layer and erodes the softer stone from the walls of the riverbed leaving the harder stone overhang.
Rock shelter formation by karst gallery cutting occurs when a river bed cuts into a formerly subterranean karst gallery, leaving the opening to it exposed on the bank.
The Chert Rock Shelter
A rock shelter (also called a shelter cave, a crepuscular cave or an abri) is a shallow cave-like opening at the base of a bluff or cliff. Through one of three forces, softer rock is worn away from the bluff, leaving the harder rock overhanging the hollowed out area. The conditions here in Coward's Hollow were tailor made for this process and you can see not only the main shelter cave, but smaller shelter caves in stages of formation as the process continues.
Most of the rock in this area of the Ozark plateau is sandstone. Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any color, but the most common colors are tan, brown, yellow, red, gray, pink, white and black. In this area the sandstone has a predominately reddish brown color.
The stream here at Coward's Hollow is formed out of an uncommon massive bed of chert rock, predominately a medium gray color, measuring up to forty feet in places. Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color (from white to black), but most often manifests as gray, brown, grayish brown.
The harder Chert resists the weathering effects of the stream bed, while the softer sandstone gives way. The creates a stream bed with a high vertical relief consisting of falls, rapids and pools. As the sandstone wears away collection points form between the harder Chert Boulders that are left behind.
Over time this process has carved out a large hollow in the side of the cliff on the south side of the stream. The harder chert remains, overhanging the large hollowed out rock shelter. Smaller rock shelters can be observed here in the process of being formed.
Season flash flooding moves gravel, sand and trees down the stream bed, further eroding the bed and bringing more gravel and boulders down from the steep Chert cliffs on either side of the stream.
A shut-in begins here with a 10 foot waterfall spilling down into a narrow stream that is scattered with massive chert boulders and lined by chert cliffs ranging from 5 to 20 feet in height.
You may encounter wildlife, including potentially dangerous critters like snakes out here, though I did not. You may also encounter biting and stinging insects and arachnids like mosquitoes and ticks.
IMPORTANTObtaining the information required to log this geocache will require you to cross a stream at the top of a 12 foot waterfall and then navigate, off trail to the bottom of the falls where you will cross back over the stream. With care and attention, this will not require any specialized equipment or training, but the potential for a fall is there and you should exercise a cautious approach with respect to the terrain at all times.
Please feel welcome to enter the rock shelter at Coward's Hollow. The zone biologist says they are not classified as caves and are not subject to the ban on entering caves on Mark Twain national Forest
Trail from parking area to Coward's Hollow is blazed with Natural Area markers like the one depicted in the image below as well as some smaller ones that bear the same symbol for Missouri Natural Areas. 