Productive Galena, Illinois and Graf, Iowa Excursions

[tombk]

This is my first post of a Fossil Trip I took. I'm also fairly new to identifying fossils and researching the geological makeup of various sites. The trip was fun and writing about it really helped me organize my finds. (Sorry to use a sharpened pencil to indicate size. I want to get one of those cool metallic-looking cubes I see on TFF. If somebody can tell me where to get one, I'd be very grateful.)

 

I recently went on vacation about 8 miles East of Galena, Illinois. I had checked with a few local and regional rock and fossils groups to see whether anybody knew of collecting sites around Galena. Nobody knew of any, so my hopes of getting some fossil collecting done while vacationing were not high. However, I have a nicer story to tell. First, I happened upon a road cut about three minutes from where I was staying that had a few hidden treasures. Second, there was also a rock quarry about five minutes from where I was staying, and the owner was gracious enough to let me go look around. Third, on the way home I was able to take a detour to the famed Graf, Iowa location.

 

So here’s my story.

 

Part I. I was staying in a rented house in an area called Galena Territory. I had noticed a few road cuts on the drive in. From the research I did, much of the outcroppings in that area are unsurprisingly from the Galena group, which is made up primarily of dolomite and limestone. It sits on top of the Platteville Group and under the Maquoketa Group of the Cincinnatian Series. On one of the local roads, about 5 minutes from where I was staying, I found a road cut that stretched for about 200 feet on either side of the two-lane road. There was a shoulder just wide enough to park on. Traffic was light.

 

The app, Rockd, using my latitude, longitude and elevation told me the rock there was from the Ordovician, 457 - 451 Ma, and stratigraphically part of the Millbrig k-Bentonite Bed. A map I found on line confirmed this. There was a fair amount of undergrowth on the bottom of the slope, especially on the West side.  This was a place where you have to enjoy the looking as much as the finding. I often thought I would quit the site, only to find a single cool piece followed by long stretches of nothing.

 

My three coolest finds were a large maclurlites. Here’s the domed side.

 

And here's the flat side

 

What I think is a hormotoma gastropod

 

And a gastropod that may be of the Lophospira species.

 

It gave me a nice feeling to find a site on my own that had these treasures.

 

Part 2. Quarry near where I was staying. I called a local quarry that yields mostly Ordovician dolomitic limestone. I explained I was an amateur fossil collector visiting the area, and the owner kindly let me go there to look around. He made it clear, quite reasonably, that I had to stay away from the machinery and from the sites where they were actively extracting stone. When I got there and introduced myself to one of the employees, he showed me a few really cool specimens they had found and had laid aside.

 

My favorite was a polished slab that contained a large portion of a receptaculites, sometimes called a “sunflower coral” even though it’s not a coral. It is possibly a calcareous algae.

 

They also had what I think were two very large Oncocerid fossils (“giant squids”).

 

 

Finally, they had a polished slab with a very large orthoceras impression.

 

After they showed me these, I mostly poked around the area just inside the entrance, where there was a fair amount of broken pieces of stone of various sizes. I didn’t feel the invitation included permission to break open rocks, so I contented myself with picking up a few small specimens, a brachiopod that sparkles with pyrite (although this doesn’t show up well in the picture) and two tiny fragments of receptaculites.

 

 

Part 3. I had read a lot about the road cut in Graf, a farm town in Iowa with a population just shy of 70. The area consists primarily of corn and soy-bean crops with a scattering of cattle. This road cut is an amazing site to find specimens of the cephalopod isorthoceras. I find it hard to fathom both how so many of these fossils exist in this one small region and how they have not all been collected by now.

 

So on my way home from Galena, I took a slight detour to visit Graf. Being both an introvert and a bit on the anxious side, on my way there I worried that there would be a lot of other people looking for fossils, that the fossils would all be gone by the time I got there, and that somehow some local authority would tell me that I shouldn’t be there and can’t collect fossils at that site. None of these worries came true. Nobody else was there collecting fossils. There were plenty to find. And not a single person stopped by to tell me I had to leave.

 

The rocks are shale, dolomite and limestone from the Elgin Member of the Maquoketa Formation. This places them in the Upper Ordovician.

 

I was there from about noon to 3 PM. There is a bike trail across from the collecting site, and I did see a number of cyclists. And there were two fairly long convoys of large farm equipment that drove past slowly. I suspect the farmers are used to seeing lone people climbing the slopes at that site.

 

Most of the pictures of the site I had seen must have been taken either in early spring or late autumn because I was not prepared for the amount of vegetation covering the slopes in the second week of July.

 

The undergrowth (which I will also call “overgrowth” and “vegetation” as the mood strikes me) kept me for the most part toward the bottom of the road cut among rocks and specimens that had fallen loose from places higher up.

 

You can see part of the rock slope in the very back of this picture. The rock in that layer is mostly limestone and dolomite.

 

Despite not having direct access to the top layers, I had an amazing haul. (And, to tell the truth, those top layers looked pretty spooky. The overhang on them is daunting.)

 

There were a few spots where rocks were visible and the weeds were cleared. Perhaps there had been small rockslides that cleared these areas, or perhaps somebody before me had yanked or hacked away the vegetation in these spots.

 

I actually found more specimens when I looked under the overgrowth than when I looked in these cleared areas. Maybe the cleared areas has been picked through recently.

 

Of course, the vegetation has defenses against marauders.

 

So be more careful than I was.

 

Luckily, the scratches were superficial and cleared quickly. (I cannot attest to the presence or absence of poison ivy. I’m not susceptible to it and am not good at identifying it.) But the thickness of the vegetation and the frequent presence of thorns limited how high I could climb in most places.

 

I mostly pulled ivy away with the pick side of my geological hammer and saw many, many fragments of isorthoceras lying about underneath for the picking. It was so much fun to spot them and fill my shirt pocket, which I had to unload several times into my rock bag. There were so many specimens to find that I collected over a distance of perhaps only 100 feet from where I parked my car. The picture below is taken from the furthest spot I collected with my car in the distance. (You can see, as others have mentioned on this forum, that there is no shoulder to the road. I pulled over into some tall grass. The ground starts to slope down fairly close to the edge of the road. Luckily it wasn’t muddy, and I didn’t get stuck.)

 

Despite that short distance, I probably found about 100 loose isorthoceras fragments of varying sizes. Here’s my haul of loose pieces all spread out back at home.

 

I also found some larger rocks with isorthoceras embedded in them. Some of these were underneath the vegetation toward the bottom of the outcropping. Some, though, I had to climb a bit higher to find. (The slope was steep and the footing was not guaranteed. Sometimes I drove my rock hammer’s pick into the ground to pull myself higher. In some places, there were a few hearty small trees that I could grab onto. But be careful, because there are also small, dead trees that break away easily and provide no support.)

 

 

 

I found one stone about two meters up that was actually fairly fragile.  I was able to break off some pieces at the edges with my bare hands. The six pieces I pulled off are less gray and are laid out underneath the larger grey stone at the upper margin of the picture. I hope the resolution of the image I uploaded is good enough for you to enlarge it and see some of the fossils in the stone pieces. The largest piece is a coquina (a rock made up almost entirely of fossils) that I brought home. I’ll show a pic of this nice piece all washed up but otherwise not prepped soon.

 

After about three hours of collecting, I was getting tired and my rock bag was getting full.  So I decided to head home. I had so many fossils by this point that a rock had to be pretty special for me to keep it. For example, this one which wasn’t particularly well preserved, I left for somebody else.

 

Here is a picture of all the specimens I collected that were not just loose isorthoceras. Again, I hope you are able to enlarge the picture, zooming in to see details.

 

And here are some close-ups of a few of the nicer ones. First the big coquina I mentioned above.

 

Here is one that contains mostly impressions.

 

Here’s another one that I like, showing how sometimes the fossils intersect each other in interesting ways.

 

Although most of the fossils there are from the same cephalopod species, there were some other fossils as well. These other fossils tended to be very small. (I’ve read that the shale layers have more of these small fossils, but I didn’t have any luck looking in the shale.)

 

Two gastropods and a brachiopod.

 

Finally, one can find rocks containing some very, very tiny fossils whose identity has been debated. Some say they are scaphopods, others say they are a different type of tube-shaped mollusk, and still others a calcareous worm tube. https://www.google.com/amp/s/vmnhpaleontology.wordpress.com/2011/07/02/graf-iowa/amp/

 

Quite a trip! And now I need to find a place to put all these new specimens. Sometimes it’s easier to find them than to organize and store them. Maybe that’s because the hunt is the fun part.

 

 

[Neanderthal Shaman]

Very nice, especially that large orthocone. That would have been one honking cephalopod. 

[deutscheben]

Thanks for a very thorough and informative trip report- my Illinois collection is mostly Pennsylvanian from the eastern part of the state so it’s fascinating to see the other side. 

[Al Dente]

This is a really nice piece that shows the telescoping of nautiloids that can be found at this site. Sometimes you can find three or four nautiloids shoved inside one another. I’ve circled some examples of telescoping on your piece. One explanation for this is septal failure that causes an implosion which sucks up surrounding nautiloids and triggers others to implode in a chain reaction. Another explanation is wave or current action shoving them together.

 

 

[connorp]

Nice finds! Glad Graf worked out for you. The large overhangs are quite unnerving. I believe they are at least in part due to commercial collectors undercutting the upper  layers to get at the nautiloid beds. I personally expect the site will get closed off not too far in the future.

 

You can get one of the nice metal scale cubes from @aerogrower.

[Wrangellian]

Thanks for the report. Minnbuckeye sent me some samples from there.. nice to see the location. I love that big chunk full of orthocones, and the little ones (scaphopods or worm tubes) are interesting.

[Yoda]

Nice finds,

Especially the Oncocerid 

[FranzBernhard]

What a great and informative first report! Thanks for taking us along!

 

On 7/19/2021 at 1:47 AM, tombk said:

It gave me a nice feeling to find a site on my own that had these treasures.

Somewhat addicting, isn´t it? .

 

On 7/19/2021 at 1:47 AM, tombk said:

My favorite was a polished slab that contained a large portion of a receptaculites,

LOL! I thought, someone tested his rock drill on that slab. Really great specimen!

 

Thanks again!
Franz Bernhard

Edited July 20, 2021 by FranzBernhard

[tombk]

22 hours ago, connorp said:

The large overhangs are quite unnerving. I believe they are at least in part due to commercial collectors undercutting the upper  layers to get at the nautiloid beds. I personally expect the site will get closed off not too far in the future.

That will be too bad, but you may be right. 

16 hours ago, Yoda said:

Nice finds,

Especially the Oncocerid

I actually didn’t find the Oncocerid. The workers at the quarry did. They didn’t offer to sell it, and I didn’t ask, although now I sort of wish I had. But I always prefer fossils I find myself.