Earth Cache
To Learn Something About Our Planet
The Lesson That You Learn Is Learned Forever
Leave Nothing But Your Footprints Behind
Karst Topography
Karst refers to geologic, hydrologic, and landscape features associated with the dissolution of soluble rocks, such as carbonates and evaporites. A common feature of karst landscapes are sinkholes which we will learn more about.
Sinkholes are formed when the land surface collapses into subsurface voids formed in the slowly dissolving rock. In Missouri, according to The Geological Survey Program, 15,981 sinkholes have been verified, the largest known of these sinkholes encompasses about 700 acres in western Boone County southeast of where Interstate 70 crosses the Missouri River.
Below is Map of Missouri showing prevalence of sinkholes.
Carbonate rocks are the basis of sinkholes, caves, sinking streams and subsurface drainage. Dolostone and limestone are the most common carbonate rocks. Dolostone is the mineral dolomite plus some calcite. Limestone is calcite plus some dolomite. Karst landscapes occur because mildly acidic water slowly act upon soluble rocks. Water percolates through soil to the bedrock, where it interacts with fractures in the rock. Hundreds and thousands of years of pressure and chemical erosion from the water causes these fractures to grow. When the cracks become large enough that they are no longer able to support the weight of the soil on top of them, a sinkhole forms. Sinkholes are natural depressions or holes in the Earth's surface. The result is an underground drainage system.
Let us now explore the sinkhole commonly known as The Devils Well.
There are many facets involved in this Earthcache. There is an underground river. There is a cave. There is also an underground lake. Each one of these could be described in more detail on their own. But we would not know about any of this if it were not for the sinkhole that led to this discovery.
Located off Route KK near Akers, this unique karst formation allows a look at the earth's plumbing. Devils Well was formed when the roof of a huge cavern, containing an underground lake, collapsed. The result was a large sinkhole, with an opening in the bottom through which you can view the lake. The water level is about 100 feet below the platform, and the lake may be as much as 80 feet deep. (It can fluctuate 8 to 10 feet depending on the weather.) A spiral staircase has been built to allow viewing. There is no admission fee for Devils Well and the area is open everyday, during daylight hours only.
In order to log this Earth Cache several tasks need to be done.
1. Take an Elevation reading at the signage. Do not use the elevation on the chart but your gps reading.
2. After taking the stairs to the bottom of the sinkhole take another elevation reading.
3. Using the measurements just taken how deep is this sinkhole?
4. What is the temperature of the water coming out of the rocks?
5. Concerning question 4. Is the water from the rocks flowing slow, moderate or fast?
6. At the iron gate measure the distance between the rocks.
7. Finally, although not required, post a picture of yourself or team with your log. I love to see who visits.
Do not post answers in log, email answers to me through my geocaching profile.