Tower Rock Geology EarthCache
Hidden : 4/8/2017
Difficulty:
2 out of 5
Terrain:
2.5 out of 5

Size: Size: other (other)

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Geocache Description:

Tower Rock, at an elevation of 500 feet above sea level, is the highest point along the Ohio River in Illinois and is reported to be the highest point along the entire Ohio River.  You will start at the bank of the Ohio River and follow the 1/8-mile trail to the top of Tower Rock for a fantastic view of the Ohio River valley.


Tower Rock
Tower Rock (photograph byW. T. Frankie)


Material to Bring:  Ruler, Camera, and Observation skills


Logging Requirements: In order to claim a find on the Earthcache you must do five things:

A. Email or Message me you answers to the following questions:
1.    Take an elevation reading at the water's edge (waypoint #1) AND at the observation platform at the top of the trail (waypoint #3). How high is the observation post?

2.    What type of limestone is exposed at the observation post (waypoint #3)?

3.    At the observation post, find and measure the length of a fossil.  What type of fossil is it and how big is it?

4.   In terms of color and texture,  how do the rocks at waypoint #2 differ from those at waypoint #3?


B. Sign the on-line log. Include with your log:
1.     A description of your visit including the number in your party, NOT THE ANSWERS TO QUESTIONS 1 - 4.

2.    Optional, but greatly appreciated:
        a. Upload a picture of your fossil and ruler.
       
        b. Upload a picture of you (and your crew) at the overlook with the Ohio River in the background.



Tower Rock Geology
The stratigraphy of Tower Rock, from the base at the Ohio River’s edge, consists of approximately 120 feet of Mississippian age Salem Limestone, overlain by 60 to 80 feet of Mississippian age St. Louis Limestone. The Salem Limestone is typically gray to almost black.  Whereas the overlying St. Louis Limestone is fine grained and cherty. Several zones of silicified singular horn coral assemblages occur in the upper portion. These horn corals can be seen in the bedrock near the observation platform and along the trail at the top.

During Mississippian time, the midcontinent of North America was a generally low-lying stable platform. Clear, warm, shallow seas entered the Mississippi Valley region, which remained almost continually submerged throughout the Mississippian Period (from about 354 to 323 million years ago). During the middle part of the period, the seas reached far to the north, and relatively pure limestones, such as the St. Louis and the Salem Limestones, were deposited over enormous areas. During the latter part of the period, the seas became more restricted, and the numerous shales and sandstones of the Chesterian Series were deposited.
Tower Rock FossilsMIssissipian fossils


Permission for earthcache placement provided by Shawnee National Forest - Hidden Springs Ranger District.   Prior to your visit plan ahead to prepare for a safe and enjoyable trip.  Please be aware you could face inherent risks of adverse weather conditions, isolation, physical hazards, and lack of rapid communications, especially in remote areas of the Forest. Search and rescue may not be as rapid as expected.

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