Green River: Shelter Cave EarthCache
Green River: Shelter Cave
-
Difficulty:
-
-
Terrain:
-
Size: 
(not chosen)
Please note Use of geocaching.com services is subject to the terms and conditions
in our disclaimer.
The Geen River at Mammoth Cave National Park
NOTE: These geological features of the Green River were observed and documented during a float trip which launched at Dennison Ferry (parking coordinates below) and terminated at the Green River Ferry 7.5 river miles downstream. While these areas may be reached on foot, they would easily be rated a 4.5 terrain. A canoe or other floatable is highly recommended. This Earthcache listed with permission from the Mammoth Cave National Park Service and staff.
Please read and follow MCNP Boating/Camping Rules and Regulations HERE!
Bats are beneficial to humans, but White Nose Syndrome (WNS) is killing them. Be aware of it by reading THIS!
_________________________________________________________________
Shelter Cave along Green River.
The posted coordinates will bring you to Shelter Cave.
Shelter Cave, located on the water's edge about one-half mile below Dennison Ferry and above Three Sisters Island has long been a stop for paddlers on the Green River. When water conditions are right you can enter by boat to a depth of about forty feet with plenty of headroom. It's a great shelter from a passing shower or a secluded spot to steal a memory.
Due to frequent flooding, bats are not residents of the cave.
A Cave Gets Started
Rain water, acidified by carbon dioxide in the soil, seeped downward through millions of tiny cracks and crevices in the limestone layers. This weak carbonic acid (the same acid as in soda pop) dissolved a network of tiny microcaverns along the cracks. As the land continued slowly rising, the Green River eroded its channel deeper. The water in the network of microcaverns drained through the limestone under the plateau toward the river. Just as rivulets converged into streams above ground, water flow paths through the limestone also converged into incrementally larger flow paths.
As rainwater continued to enter the system and more limestone was dissolved, the microcaverns enlarged. Because the major drains carried the most water, they enlarged the most. Caves were forming. As the Green River cut deeper, the water table continued dropping to the same base level as the Green River. New underground drains formed at levels lower than the older ones, and the older channels emptied. Thus the oldest cave passages are the closest to the surface, and the youngest horizontal passages are the deepest underground. At the present water table, cave passages are still being formed.
Surface Clues
As you approach the vicinity of Mammoth Cave, several clues suggest the existence of caves. Road-cuts along highways have vertical exposures of layered grayish rock, often broken into irregular blocks at the top where erosion has widened vertical cracks across layers. Between the layers you may see the tiny openings in the limestone that are the first stage in the formation of a cave.
The landscape along the highway also has special characteristics. You will not see surface streams. Instead, you will see myriads of crater-like depressions called "sinkholes." These sinkholes are places where run-off may quickly enter the limestone aquifer. Cave drains carry the dissolved limestone away, and the surface soil settles, creating the bowl-shaped depression. If the sinkholes drains become plugged with soil, then the water cannot drain underground and a pond forms. Occasionally the drain becomes unplugged and a pond as large as several acres will disappear overnight.
This landscape is called karst topography. It is found along and to the southeast of Interstate 65 near Mammoth Cave National Park and referred to as the Sinkhole plain. At its southeast edge surface streams sink underground joining the drainage of thousands of sinkholes. Continuing northwest they become the underground rivers of Mammoth Cave.
________________________________________________________________
LEFT: Along The Green River CENTER: ARF! at The Cave RIGHT:Three Sisters Island Stop
________________________________________________________________
Post a photo and share your visit!
TO LOG your visit and to demonstrate the educational value of this site, please email the answers to the following questions to ARF!.
1. What is the cave topography called?
2. What activates rain water and allows dissolution of limestone?
3. How tall is the opening of the shelter cave?
4. Why is WNS 'bad news' for humans?
Please email your answers first, then LOG THE FIND. Do not wait on a reply from me. FINDs which do not meet logging requirements will be removed.
Earthcaching: Leave No Trace!
This Earthcache listed with permission of Mammoth Cave National Park.
Additional Hints
(Decrypt)
Cubgb naq #4 ng gur fvgr, rqh-pnpuvbany nafjref ner va gur grkg.