Highway 50 Filled Sinkhole Complex EarthCache

This cache has been archived.

Hill Folk: Time to let this one go.

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Hidden : 1/25/2016
Difficulty:
1.5 out of 5
Terrain:
1.5 out of 5

Size: Size: other (other)

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Geocache Description:


This is an Earthcache located along U.S. Highway 50, about five miles west of Jefferson City. Please do not park along the highway to do this Earthcache. There's parking along a side road (parking coordinates provided below) that will allow you to access the cache safely. From there, you can walk to the cache site along the wide berth between the highway and the formation. If you have little ones with you, keep an eye on them because the highway can be busy at times!
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Standing before you is an excellent example of a filled sinkhole that was exposed during the widening of Highway 50 from two lanes to four. The fresh cut allows us to see this phenomenon in a most excellent fashion. To the east a bit are two more filled sinkholes, just smaller than this one. Additional listed coordinates below mark where they are, for those curious to see them.

How were these 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.
SOURCE: Geologic Wonders and Curiosities by Thomas R. Beveridge,
Second Edition, revised by Jerry D. Vineyard, 392 p., 163 figs., app., 1991.
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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. Again, park at the supplied parking coordinates and walk to the cache site along the wide berth between the highway and the formation. If you have little ones with you and you bring them along, keep an eye on them because the highway can be busy at times!

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. Name one way filled sinkholes can cause problems for people.

5. 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.)



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