Southern Illinois Field Trip

Field Trip Stops

"I really didn't mind [the laundry room], it's all about the experiences we have and what we make of them plus it's a great story to tell people."

"The area we went through was vastly different than I could ever have imagined Illinois... Africa collided with the North American Continent [producing] the Illinois Basin, the La Salle Anticlinorium, the Ozark Dome, the Cincinnati Arch and the Rough Creek Graben all [of which] sort of intersect."

"[We also saw] Liesegang banding... caused by iron... in groundwater... the iron congregates in these unique bands." "[which] reminded me of iron framboids at Buffalo Rock State Park."

"I had a hard time getting good samples of fluorite and I really did not like this stop at all.

"I walked along so very scary high trails, and I also walked throughout the crevasse called "fat man's revenge."

"We were instructed to stay away from the high wall, which was a good idea, because rocks came tumbling down the whole time... Kami found a decorated ammonoid and Jason found some [too]... Once again, I found absolutely nothing, and we were moved out before we really had a chance to collect anything."

"I wasn't having much luck, I was only getting dirty. Soon we were told it was time to leave. I was upset, I didn't find anything, so I found a big piece of shale, raised it over my head and dropped it. It split apart and there was a fossil bivalve! I was very happy."

"I found a trace fossil... some mollusk shells and some leaf prints [at Horseshoe Upheaval]."

"I also found my only fossil of a trilobite here. I was excited... because my main goal in these field trips was to find a trilobite."

"My least favorite part of the trip was when my car broke down and spit coolant all over... Everyone stuck by me and reassured me that it was not my fault - that it was going to be okay."

"There was a definite change in the group -- we were a single unit. In 45 minutes we went from classmates to buddies... Would not have changed a thing and would even sabotage somebody's car next trip so we could do it again."

"That was the first time I ever learned how to set up a tent. I snuggled in for the night but I couldn't sleep... then it started raining... I woke up the next morning a little wet around the edges... I was happy because I actualy camped, something I had wanted to do for a long time..."

"Then came the storm... we got up and ate breakfast and had coffee. Everyone was great, sharing and helping others. The day turned out to be warm and sunny."

"I have to say that it was an experience that I'll never forget. I didn't want it to end... I looked out the window [going home] at the perfect roundness of the setting sun and though to myself, I'm glad I came... because it opened my eyes to all the countless possibilities out there. I made a promise to myself that day to keep my mind open and explore all the places that I only dream about. Maybe one day I'll be leading a classroom of students on a field trip of my own..."

Links and Information:

• Matt Rubschlager's photos from Spring 2001 field trips show Kankakee, LaSalle and photos from our downstate Illinois trip.
• Illinois Bedrock Geology from the Illinois State Geological Survey is a new full-color image.
• U.S. Forest Service Shawnee Website.

• Geologic Overview: The area is heavily faulted and uplifed from east to west. The two high points are Bald Knob at 1,048 and Williams Hill at 1,064 feet. Most of the rocks are sedimentary and relatively flat-lying. Some igneous and metamorphic mineralization is known.
• Rosiclaire: A picturesque river town. Contains a fluorspar mine and museum. Fluorspar was mined nowhere else in the United States until this mine closed recently because it could no longer compete with imported fluorite. Fluorspar formed from super-saturated minerals at great temperatures and pressures deep in the earth. When driven through faults, the mineral rich fluids congeal into the thick, layered deposits of fluorspar, the state mineral of Illinois. A now-defunct website about the mineral said:

  "Fluorospar is mined in Hardin and Pope counties. Over 200 million years ago, a mass of molten magma pushed up from the earth's interior and bulged most of the area of Hardin Counties, Illinois, into a huge dome. During the ages that followed, huge dikes of black igneous rock from the abysses below split the region in many places from southeast to northwest. When the period of volcanic activity ceased, the molten magma began to cool and contract, and the many mineral components of the mass began to separate out. As the mass shrank and subsided, the region collapsed into a series of long, narrow fault blocks... through these fault fractures...gasses heavy with fluorine, lead, zinc, barium, and with small amounts of cadmium, germanium and silver [rose]. During a period of certain temperature and pressure conditions, a chemical reaction took place between the gases and the rock walls of the fissures, and the minerals were deposited in veins and as replacements of limestone beds. Thus were formed the ore bodies of fluorospar or fluorite (CaF₂), sphalerite (ZnS), galena (PbS), barite (BaSO₄), and calcite (CaCO₃... At the close of the Pennsylvanian geologic period, 200 million years ago, the area stood high out of the sea and was subjected to erosion. The long years of weathering removed some 3,500 feet of the domed area, leaving the relatively low and scenic hills of today, and exposing for discovery veins and bedded deposits of fluorospar."

• Jackson Hollow: Possibly the most beautiful spot in Southern Illinois but accessible only by horse back and hiking. The only spot with a parking lot allows a twenty foot drop into the canyon. Incongruously, a railroad runs through it, although you would never see it until next to it. It goes through the longest tunnel in Illinois.
  
• Hicks Dome: Pilots flying over this hill were amazed to see the shape of a volcano from the air. In a region of sedimentary rocks, there are some igneous outcropping, many faults and unusual surface formations all caused by some event. The first geologic report suggested that a volcano exploded before reaching the surface but bulged the the surface approximately 150,000,000 years ago. The event is referred to as a "cryto-explosion" since they did not precisely know what happened. This is not how Hicks Dome formed. We now know that Illinois over rode a hot spot, creating this igneous intruded and faulted structure.
• Saline County Fish and Wildlife Area - Saline and Gallatin Co. is operated by the Illinois Department of Natural Resources. At 2,200 acres, SCFWA is one of the largest state-owned sites with many features not found in better marketed state parks. Attractions include Glen O. Jones Lake, Cave Hill Hiking Trail and three shorter trails, and Upheaval at Horseshoe, an interesting geological formation."

Other Nearby Fossil-Hunting Localities and Information

• The Cincinnati Dome has long been one of the most famous Ordovician fossil areas in North America, particularly for bryozoa. The dome covers a large area of southeastern Indiana and adjacent parts of Ohio and Kentucky.
  • Bryozoa Page University of Kentucky shows some southern Illinois fossil hunting localities.
• Kentucky road trips
  • "KY Highway 131 road cuts: A new series of road cuts between Interstate 65 and Fort Knox contains geodes and fossils. The geodes can contain calcite which may be highly fluorescent and/or phosphorescent... fossils are from the Mississippian age and include brachiopods, crinoids, shark teeth)."
  • "Taylorsville Road Cuts, Spencer County, KY. Upper Ordovician fossils abound in the numerous road cuts around Taylorsville. Brachiopods, byrozoans, cephalopods, clams, corals, scolecodont teeth and snails are often found. In certain road cuts, many brachiopods are lined with calcite crystals and sometimes with dolomite and celestine."
  • "Sulphur Road Cut, Crawford County, IN. This is a famous Upper Mississippian fossil locality. It is known for articulated crinoids, abundant blastoids, Archimedes bryozoans, brachiopods, snails trilobites and trace fossils. Vertebrate remains include a variety of shark teeth and dermal scales, and rare coelancth and chimerids remains."
    Quotes from a now-defunct website.