Sandstone of Wildcat Den State Park EarthCache
Sandstone of Wildcat Den State Park
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This journey through the sandstone features of Wildcat Den State Park will take you up and down a 1.25 mile loop trail. You will not have to leave the established trails. There is no climbing or rapelling allowed in Wildcat Den State Park. Please respect all the rules of the Iowa State Parks.
Geology of Wildcat Den State Park Wildcat Den State Park, one of the most unique parks in Iowa, lies 12 miles from Muscatine and 18 mile from Davenport. Located in an area of rugged terrain and rock exposures about one mile north of the Mississippi River, the 417 acres of the park offers a variety of attractions, including some interesting and unique natural resources. Most of the park’s natural resources are accessible via its trail system, which leads to such fascinating sites as Steamboat Rock, Fat Man’s Squeeze and the Devil’s Punch Bowl. In addition the spectacular bluffs provide excellent views of this beautiful area and Pine Creek. The sandstone features of Wildcat Den State Park were created during the Pennsylvanian Period, in the Bashkirian and Moscovian epochs. The bluffs and other features are basically sandstone laid down during the Moscovian epoch (311.3-303 million years ago). This sandstone is known as the Cherokee Group. Also exposed is the Caseyville Formation, created during the Bashkirian epoch (322.8-311.3 million years ago). This formation is the oldest Pennsylvanian unit in the Upper Mississippi Valley region. Begin your journey at the listed coordinates. Proceed down the trail towards the Devil’s Punch Bowl, N 41° 28.086 W 090° 52.988. The Devil’s Punchbowl is a bowl-shaped feature sculpted by the erosive forces of the water of an intermittent creek and the sediment load cascading over the bluff. This feature showcases some of the interesting features of the Cherokee sandstones. This area of the park provides an excellent opportunity to observe cross-bedding and Liesegang bands in the sandstones. In geology, cross-bedding refers to inclined sedimentary structures in a horizontal unit of rock. Cross-bedding structures form in ripples and dunes. Sand grains bounce up side of a ripple, and then tumble down the lee side. Separations of heavy minerals and cyclical change in flow cycles cause the different bedding planes. Cross-bedding can form in any environment where water or wind flows and sand or gravel exists on the bed of the system. It is most common in stream deposits, tidal areas, as well as in sand dunes. Careful study of cross-beds can often determine ancient water flow or wind directions. Notice the parallel lines which are evident on the sides of the Devils’s Punchbowl. The change in direction of the lines shows cross bedding. Liesegang bands are curved to irregular bands which are deposits of iron minerals. These bands are reddish-brown to yellow in color and are common in cliff-forming sandstones. Much of the red iron mineralization in these bands is hematite, goethite and limonite. The source of the iron is the carbonate mineral siderite. But when siderite weathers, it oxidizes forming the yellow-brown mineral limonite as well as hematite and goethite. Estimate the volume of the punchbowl and submit the answer with a short description on how you did the estimate. Proceed to N 41° 28.061 W 090° 52.943. Here you can see an exposure of shale of the Pennsylvanian Caseyville Formation in a small unnamed creek. The Caseyville Formation is the oldest Pennsylvanian unit in the Upper Mississippi Valley region. The Caseyville exposures in Muscatine County represent a northern outlier of the formation. Caseyville strata in Wildcat den State Park consist exclusively of carbonaceous shale and coals, both with abundant fossil plant material. Most of the plant material is unidentifiable. Notice the iron rich seepage at the base of the rock. You can tell by the prominent rust color. Your next stop will be the Devil’s Lane and Fat Man squeeze. The junction of these two features are at N 41° 28.207 W 090° 52.893. The passageway between the bluff and Steamboat Rock is known as the Devil’s Lane. A second, narrower passageway joins the lane to the right. This narrower passage has been named the “Fat Man’s Squeeze”. The sandstone formations of Steamboat Rock (N 41° 28.203 W 090° 52.882) and Fat Man’s Squeeze have been subject to almost 150 years of “name carving” or graffiti. The carvings date as early as 1861 and some of the earliest carvings may have been buried by erosional deposits along the trail which leads to these formations. Please respect the park and do not carve into the sandstone. While you are here estimate the width of the Devil’s Lane. Close by is Steamboat Rock, N 41° 28.203 W 090° 52.882. This formation may be different from other sandstones in the park, probably DesMoinesian Spoon Formation of Illinois. These sandstones are notably micaceous, feldspathic litharenites with rock fragments of sedimentary, metamorphic and igneous components. Your final stop is Wildcat Den Cave, N 41° 28.258 W 090° 52.887. This cave may have been utilized by Native Americans, although no investigation for artifacts has been undertaken. This Pennsylvanian Cherokee Group sandstone exposure is where a swale was filled by a deposit of mud mixed with rock pieces. This mud and rock mixture weathered out leaving an opening in the pure sandstone. To the north of Wildcat Den is a smaller sandstone cave in a higher up the bluff. This feature appears to have developed by preferential weathering along two inclined rock fracture surfaces. Estimate the height of the main overhand of Wildcat Den cave. Recap of logging requirements: Send all answers to IowaBeaver through the geocaching website. Please do not post in your log. 1. Estimate the volume of the punchbowl and submit the answer with a short description on how you did the estimate. 2. While you are here estimate the width of the Devil’s Lane. 3. Estimate the height of the main overhang of Wildcat Den cave. A map of the park can be obtained from the following website: http://www.iowadnr.com/parks/images/maps_pictures/wildcatmap.pdf References: http://www.palaeos.com/Paleozoic/Carboniferous/Pennsylvanian.htm http://en.wikipedia.org/wiki/Cross-bedding Anderson, R. and Bunker, B., ed., The Natural History of Wildcat Den State Park, Guidebook 64, Geological Society of Iowa, 1 Nov 1997. This cache was approved by the Wildcat Den State Park Ranger.
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