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Kansas Toadstools Earthcache

A cache by PathfinderMark Send Message to Owner Message this owner
Hidden : 12/05/2010
Difficulty:
1 out of 5
Terrain:
1 out of 5

Size: Size:   large (large)

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Geocache Description:

NOTE: ROAD CONSTRUCTION HAS CLOSED REST AREA AT GZ AS OF 6/15/2012.

As an earthcache, there is no “box” or “container” to discover. Rather, with this cache, you discover something about the geology of the area. For more info, consult www.earthcache.org

For paperless cachers, the logging requirements are at the beginning of the description.

Introduction: This earthcache is only available at the EASTBOUND I-70 rest area near Ellsworth, Kansas (mile marker 224). It is completely handicap accessible, as there is a paved sidewalk that goes around the toadstools. Even if you don't need to use the facilities, this rest area is worth a geology-stop!

Logging Requirements:
Send the answers to #1-#5 to me through my geocaching profile. DO NOT post the answers to any logging requirements on this site.

1. List the name “GC2K3Z6 Kansas Toadstools Earthcache” in the first line of your email. Also, list the number of people in your group.
2. How many “toadstools” are on display at the rest area? How many “feet” does the largest toadstool have? (N 38 51.357 W 098 07.439 is another point on the sidewalk that gives you a great “rear view” of the toadstools)
3. What color(s) are present in the sandstone concretion?
4. Does the texture resemble that of “concrete” or “plaster of paris”? Is the “foot” of a different texture than the toadstool top? Based on your observations, do you agree with area geologists that this is a septarian concretion? (see description below)
5. Measure the height, width, and breadth of the largest toadstool. How tall is the
foot/feet”?
6. (optional requirement based on GC.com guidelines, but it sure helps verify your smiley if your answers to the above are not “quite right”) Post a picture of yourself and/or your GPS with your log that shows and/or your GPS in front of the bathroom OR with a lesser toadstool (not the one used for logging requirements); OR list the two organizations who erected the historical/geological marker at the cords.

I will only respond if you have incomplete logging requirements. Go ahead and log your cache

The toadstools are visible for examination right beside the restrooms! Sidewalks lead you to within 10' and informal trails allow you to even touch the rocks, feeling their texture and density.

Geology:
The Toadstool formation that you see are actually concretions, some very large ones!

What are concretions? Concreations are formed by materials such as carbonates (calcite) or amorphous or microcrystalline forms of silicas (chert, flint, jasper). In some cases iron oxide is even present (or the main ingredient).

They are formed when sedimentary rocks, such as siltstone, mudstone, or sandstone are still being formed. It is believed they form during the diagenesis of a deposit, usually shortly after the enclosing sediment has been buried. They are believed to occur when a considerable amount of cementing material precipitates locally around a nucleus, often organic, such as a leaf, tooth, piece of shell or fossil. In effect, the mineral acts as a cement, filling in the pores between the sediment grains. The Dakota Sandstone present in this area is absolutely filled with plant fossils, and likely many of the huge concretions present in the area are formed around single fossils, or more likely deposits of formerly biotic material.

Generally, concretions are harder than the rocks around them; thus, concretions tend to “weather out” of a hillside or plain thanks to events such as erosion or landslides when the surrounding non-cemented rock/soil is removed leaving them exposed. Concretions in Kansas are formed from any of a number of minerals, including calcite, limonite, barite, pyrite, or silica. They vary widely in shape and size. The smallest are oolites, which can be smaller than the head of a pin. At the other end of the spectrum are the huge spherical concretions such as the ones you see in front of you. The largest of this type of concretion is about 27 feet in diameter!

The exteriors of septarian concretions are crisscrossed by a network of ridges, giving some of them the appearance of a turtle shell. Geologists think they were formed by the shrinkage of concretions, which caused cracks to form, followed by the deposition of such minerals as calcite. When the concretion is exposed to weathering, the softer parts between the calcite-filled cracks are eroded and the cracks extend above the surface of the concretion, like ridges or little walls.

Further Information:
During the Cretaceous Period (that interval of geologic time from about 144 to 66 million years ago), Kansas was once again under water (for the third time). Unlike the relatively shallow seas of the Pennsylvanian and Permian, the seas that advanced and retreated during the Cretaceous were deeper and more widespread. Three principal rock outcrops characterize the
Smoky Hills—the sandstones of the Dakota Formation, thelimestones of the Greenhorn Limestone Formation, and the thick chalks of the Niobrara Chalk.
The Dakota Formation sandstones crop out in a wide belt from Rice and McPherson counties, in the south, to Washington County, in the north. They are the remains of beach sands and sediments dumped by rivers draining into the early Cretaceous seas. The hills and buttes in this part of the Smoky Hills, such as Coronado Heights in Saline County, are capped by this sandstone and rise sharply above the surrounding plains. The Dakota Sandstone in this area is much more resistant to weathering than typical sandstone because iron oxide (dark brown) is present throughout the formation. You may even see some of the staining in the toadstool concretions!

Congrads to madmallard for FTF (First to Finish logging requirements on 12/6/2010

Resources:
Buchanan, Rex and James R. McCauley. Roadside Geology of Kansas. University of Kansas Press: Lawrence, KS. 1987.

Kansas University Geological Society – (visit link)

Concretions – Wikipedia – (visit link)

Dakota Concretions – (visit link)

Additional Hints (No hints available.)



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