***** FOSSIL COLLECTING AT THIS SITE IS PROHIBITED. IT IS ILLEGAL TO COLLECT FOSSILS/ROCKS ON STATE PROPERTY. ANY LOGS INDICATING THIS WILL BE FORWARDED TO THE PROPER AUTHORITIES. *****

Depending on water levels in the lake, you may have to wade in the water for this earthcache. Next to the boat ramp you will find rocks in the water that seem to be regular rocks until you pick them up. Then you will see what makes them different. You can see planolites in the siltstone and sandstone.

The rocks belong to the Borden Group of the Mississippian era. At this time, Indiana was covered by a shallow sea and this area was the delta part (like New Orleans now). The rock in this area is about 485-800 feet thick. There are 3 layers to this formation: New Providence which erodes easily, Spickert Knob, and Edwardsville. The Edwardsville formation will have lots of sandstone and siltstone, with some limestone, chert, and iron.

Worm markings are very adundant throughout the uppers levels of the Borden Group and serve as another distinguishing feature. The markings vary from minute, thread-like forms that are less than 1mm wide to larger marking as much as 10mm in width. These are worm traces and burrows.

These worm burrows and trace fossils are called planolites. They are simple, unlined, unbranched cylindrical or subcylindrical infilled burrows, straight to gently curved, horizontal to oblique to bedding planes. Burrows may even cross-over. The lithology. or general characteristics, of fill differs from that of host rock. You will notice that the planolites are a darker brown color than that of the host rock. The grains in the sandstone allow the trace fossils to remain intact.

To get credit for this earthcache, send answers to the following questions to my account.

1. Locate a planolite and describe what you see.

2. Does it feel any different that the host rock?

3. Why do you think the burrows remain in these rocks?

4. Post a picture of yourself (face not required) or a personal item at the site.

***** FOSSIL COLLECTING AT THIS SITE IS PROHIBITED. IT IS ILLEGAL TO COLLECT FOSSILS/ROCKS ON STATE PROPERTY. ANY LOGS INDICATING THIS WILL BE FORWARDED TO THE PROPER AUTHORITIES. *****

Sources: IGS, Jill Vance, and KU Ichnology