Fossil Field Trip: Fossil Reefs Under the Feet of the PCA GA

On my trip to Kentucky this week to attend the PCA GA I took some time to do some geological sightseeing.  I hope I can convince you that it was a lot more exciting that it might sound:-)   Below are some pictures I took at two locations.  The first are from the Falls of the Ohio State Park (in Indiana).  Larger version of each can be viewed by clicking on the image.  I make some limited comments about how these pictures relate to some of the themes of recent blog posts.

Looking out over the fossil reef appearing just above the Ohio River. The reef appears again on the other side of the river and covers many hundreds of square miles under the hills of Kentucky and Indiana but is exposed here where the Ohio River has eroded the rock layers from above. This is all fossil coral that you see in this picture. See close ups below. Image: Joel Duff – free to use with credit to this page.  Click for much larger image.
Looking downstream the coral reef is less smooth but the variety of corals is greater.  Image: Joel Duff
An image from above the state park showing the extent of the exposure of the coral reef rocks. Image:

The Falls of the Ohio State Park really is a remarkable place.  You can get right down to the Ohio River because there is a dam just upstream that redirects most of the water into a lock system.   This spring has been dry in the Midwest and so the coral reef was fairly well exposed but in the fall there are times where the fossil reef is visible all the way across.   I wonder how many commissioners at the PCA General Assembly realized that the convention center in Louisville sits right on top  of this huge coral reef?  As they listened to a seminar on the age of the earth they were sitting on one of the most difficult forms of fossils to explain in the context of a young earth.  If any of them crossed over to Indiana and walked down to the river’s edge they would have discovered a truly amazing fossil site.

A view of the fossil coral reef from the visitor’s center of the Falls of the Ohio State Park. All the rock you see if fossil coral. When the Ohio River is very low you can walk all the way across this section because the remainder of the river is running through the locks. Image credit: Joel Duff – permission to use with credit to this address.
I am standing on the reef looking at the surface. See the next couple pictures for a close-up of the surface. I watched numerous people come down and walk out on the rocks and many realized after a while that there was something “weird” about them. Several remarked that it seemed like the rocks were made of fossils. Many probably don’t realize that what they are standing on is nearly 100% fossil coral and bryozoans.  The surface has been worn smooth by the river waters.  Image credit: Joel Duff

The rocks layers you climb down to get to the reef have fossils but that doesn’t prepare you for what you are about to see when you get to the rocks that spread out over the floor of the river.   You end up walking out on a nearly smooth surface that is the eroded tops of a giant fossilized coral reef.

The same fossil reef surface as above but now closer. You can see that it is made of a jumble of coral that has been worn smooth by the river. As I walked over several acres of this fossil reef I could see that some areas were represented by different species and densities of corals and bryozoans just like modern-day reefs. Image credit: Joel Duff
Another close-up of the fossil coral reef. I cleaned this surface with some fresh water to make the fossil corals more clear. Really quite spectacular! Image credit: Joel Duff
A spectacular fossil coral up-close showing the fine detail that is preserved in the fossilization process. Image credit: Joel Duff. Click image to get much closer.
Here we see layers of fossil reef showing a history of reef building.  The top layer is about 4-5 inches thick here lying on another fossil reef layer that is a foot thick.  Overall there are 4-5 sets of fossil reefs stacked on top of each other suggesting a long period of reef development. Also notice that the organisms that make up these two reefs are different.   The small loose shells are not fossils but present day shells.  Image credit: Joel Duff

Fossilized reefs present one of the greatest challenges to the young earth models.  The usual explanation is that the reefs represent reefs that existed prior to the Flood but were dislodged by the Flood and then deposited in the geological column.  A visit to a site such as this immediately dispels such an idea.  For one thing the size of the reef is enormous and it would be incredibly unlikely that such a large object could be transported hundreds or thousands of miles and floated onto several thousand feet of sediments below without itself being broken up.    More importantly these reefs are very complex and it isn’t just a single reef.  The picture above shows that the corals have grown in pancake type layers one on top of another.  This strongly suggests a succession of reefs at the same location.  One reef growing on another.  Probably one reef was either drowned by rising sea levels or left high and dry by lower sea levels. Then when sea levels returned to a few feet above the old reef a new reef took hold and grew on top of the older and now dead reef.  This must have happened many times at this location.  Flood geology can not explain the multiple layers each of which would have taken hundreds of years to grow.   Each layer is composed of a different combination of corals. If they had all grown together at one time why would there be a change in the types of coral used in each layer?  In the picture below you can see many layers of rock above the fossil reef layer.  Even in each of these layers of rock there are thin layers of coral and other marine organisms so there were even other generations of coral although they are mixed with sedimentary layers of rock suggesting they were buried in sediments periodically.

In the foreground is the main section of fossil reef. Here you can see that above this fossil reef are many layers of other rocks. These rocks include some less pristine coral reef

Below are pictures from a road cut just northeast of Louisville KY.

Here is a road cut just off of I71 in Kentucky just northeast of Louisville. Here there are about 25 feet of hundreds of thin layers of rock most of which are loaded with marine fossils. Image: Joel Duff.

This layer of limestone is chock full of fossils with some thin layers being composed of a greater  percentage of fossils than rock.  These are the types of marine  fossil bearing rocks that I referred to in my article about the number of fossils in the fossil record.

Just around the corner from the limestone fossil layers above lies this section of rock which would lie above that other section. Here, there are thick layers of fine-grained rock with thin, very discrete layers of a darker, fossil bearing, softer rock.  The vertical line running down the rock is the drill hole for the dynamite.  Note the lens cover for scale.  Image: Joel Duff

What is really remarkable about the picture above and below is the sharp distinction between the reddish rock and the black layers of rock that have fossils.   These are the kinds of sharp breaks that flood geology has great difficulty explaining but conventional geology has little difficulty with.

A close-up of one of the thin layers of fragile fine-grain clay like rock that has some marine fossils that lies between thick (several feet) layers of fine-grained rock with very few or no fossils. This 4 to 5 inch thick set of many thin sheets of rock can be seen running hundreds of feet along the rock wall varying little in thickness. Image: Joel Duff
Just above those thin layers of limestone is this much thicker layer of fine-grain rock.  No evidence of fossils.  These layers go on horizontally for 100s of feet with no disturbances in the banding pattern.  Image: Joel Duff

Really great rocks and fossils in Kentucky. In that state it is hard to find a location where you can’t find a fossil.

5 thoughts on “Fossil Field Trip: Fossil Reefs Under the Feet of the PCA GA

  1. Hello, Natural Historian, just a friendly reply to your comment about sharp breaks–I would argue that sharp contacts are exactly what would be expected from the erosive power of periodic large scale currents operating over very large areas. On the other hand, the extensive horizontal layers of different lithologies in your excellent photos are hard to analogize from modern reef systems. In addition, the closeup reef photos seem to indicate reef breccia, which would be expected to result from the strong currents of a catastrophic global marine transgression.

    In addition, examination of landscapes reveals that erosion, not deposition, is the dominant process on the earth today, and the laterally continuous and horizontal layers of even thickness seen in your photos are difficult to find currently in nature on the scale seen in the fossil record.


    1. HI SJ, thanks for the comments. You are quite right that close-ups of the reef fossils are more than likely an assortment of collected debris. These make for the prettiest pictures. what is remarkable about the location is that as one walks around on this varied reef/rock surface is that the character changes. There are areas of large reef organisms and then areas between that are filled with these more jumbled bits. It really is reminiscent of a modern reef that is not a 100% area of living coral but is patches of coral with dead debris zones. Where the waves are pounding the outer reef they are breaking up portions of the reef so that the interior will have a different look. This is what is seen in this reef complex. A highly varied set of conditions but clearly many corals have grown in place rather than being transported. There are thousands of feet of layered sediments below and several hundred above in the area so this is not just a collection of corals washed into place but they are cemented together in a community that resembles a modern community rather.
      Regarding the lateral continuous horizontal layers. I will grant that locations are not common though on some continental shelves and the black sea etc there are going to be incremental layers of quite even proportions forming. However, I do think that these layers we see here are the result of conditions that are different than we have today. When the entire Midwest was a shallow sea with higher sea levels thousands of square miles would have experienced similar depositional conditions and with changing salinity etc.. you would get changes in the text of the sediments. I don’t really see much of problem with their presence even if we don’t see them forming to this extent today. Just because something is not happening today doesn’t mean it didn’t happen in the past and that the evidence doesn’t’ support and point us to seeing that it did happen. I think we will just have to disagree about the sharp breaks.


      1. Do you have a reference for the “thousands of feet of layered sediments below and several hundred above?” This is the definitive answer to the claim that fossil reefs are post-Flood, but too often ant-creationists forget to mention such crucial facts. Thanks


        1. Hi Ted, Here is one quick figure of the geological column from the Ohio river valley area that represents much of the Ohio, Indian, Kentucky region. The reefs are Devonian in age so the layers shown in this figure above that are stripped away in the Ohio Valley to expose the reef but thousands of feet of rock are found below them known from hundreds of drill cores in search of oil in the midwest.


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