Highway 63 Filled Sinkhole EarthCache
Highway 63 Filled Sinkhole
-
Difficulty:
-
-
Terrain:
-
Size: 
(other)
Please note Use of geocaching.com services is subject to the terms and conditions
in our disclaimer.
This is an Earthcache located along U.S. Highway 63, about four miles north of Vichy. While there is good parking along the side of the road, as there is a wide shoulder, if you have little ones with you, keep an eye on them because the highway can be busy at times!
______________________________________________________________________________________________________
Standing before you is an excellent example of a filled sinkhole that was exposed during construction of Highway 63. This road cut allows us to see this phenomenon in a most excellent fashion. How are filled sinkholes formed? Read on.
Sinkholes are features that are common in areas of karst topography. Karst areas are those characterized by many sinkholes, caves, underground streams and larger springs resulting from the dissolving action of percolating water in relatively soluble rocks such as limestone and dolomite. Rainwater absorbs carbon dioxide from the atmosphere and a weak carbonic acid is formed. As this water percolates through limestones and dolomites it dissolves them.
The state of Missouri...affectionately known as The Cave State...is one of the major homes of karst topography within the United States. Some of the major karst areas of Missouri are in St. Louis, Perry. Ste. Genevieve, Cooper, Greene, Boone, Christian, Phelps, Pulaski and Howell Counties.
Just as the Earth takes the time to create a sinkhole, it does not always like the holes it creates. Nature is often soon at work to fill them, usually late in the history of the sinkhole. The filling materials and methods are quite varied and in some cases, the mechanics and chemistry involved are still unknown.
There are positive aspects of filled sinkholes, with one such benefit being an economical one. Quite often, valuable minerals have been taken from them. For example, millions of dollars worth of fire clay have been and are being mined from filled sinks in an area of east-central Missouri, east of Highway 63 between the Missouri River and Interstate 44.
Conversely, filled sinkholes can cause problems. They can be a nuisance to those drilling water wells, because a well encountering such unsound material must be cased through it to prevent caving into the hole. In some cases, the filling material may contain enough pyrite (fool's gold) to be a nuisance as an acid producer, potentially damaging casing and pumping installations as well as making the water undrinkable. Filled sinkholes exposed by highway cuts create engineering problems because the filling material is often rather unsound rock such as clay, shale, poorly-cemented sandstone and other fractured, rotten rocks of various types. As a result, the dangers of rock fall and slumping of the fill material onto the right of way is always present.
One of the largest filled sinkhole exposures in the state is located at the north edge of Rolla, Missouri. It's located near the Vichy Road overpass, to the west of the Highway 63 overpass. It is approximately 200 feet wide and about 40 feet high. This filled sinkhole structure, while not as big, is still quite impressive in size.
SOURCE: Geologic Wonders and Curiosities by Thomas R. Beveridge,
Second Edition, revised by Jerry D. Vineyard, 392 p., 163 figs., app., 1991.
______________________________________________________________________________________________________
To log this Earthcache, please email me the answers to the following questions. Any logs that do not follow these requirements will be quietly deleted.
1. What is one valuable mineral that is removed from filled sinkholes?
2. What is the approximate height and width of this filled sinkhole?
3. How would you describe the rock fill of the filled sinkhole, compared to the surrounding rock?
4. Describe the color of the filled sinkhole's rock, compared to the surrounding rock.
5. Name one way filled sinkholes can cause problems for people.
While completely optional and not required, it would be nice to post a photo of yourself with filled sinkhole behind you.
Additional Hints
(No hints available.)