Railcut Coral

One day, last summer, I was pleased to discover a railcut not far from my house. I decided to check it out. It doubles as a bowling ball graveyard.


The exposure is a short distance away.


Silurian rocks. I'm not sure of the exact strata, but I want to say interreef upper Racine Formation.  My time was limited and after a brief look around, it seemed barren of fossils. The rock was embedded with chert nodules and a sort of dull beige color when split. Because it was summer and the foliage made it difficult to fully investigate, I decided to return in the fall.


Below is some exposed strata after the leaves had fallen. The layers are dipping slightly to the east. I walked a little west and came across a large tabulate coral loose on the ground. 


When I returned home, I noticed it was silicified and completely covered in tiny quartz crystals- a change from the dolomitized corals I'm used to finding in this region. Not a particularly attractive specimen, I decided to slice it up to have a look at the internal structure. Here is a chunk ready to be sliced.


To be continued...





Comments

Post a Comment

Popular posts from this blog

A rare find in the Pennsylvanian Black Shales

Image
On August 17th, I went on a group trip to the Starved Rock Clay Pit. I was specifically looking for some Listracanthus parts, and upon splitting open a large septarion nodule measuring roughly 2ft across, came upon what looked at first like a poorly preserved denticle. Upon returning home and examining more closely, it appeared to have segmentation. After showing photos of the specimen to Dave Carlson and Jack Wittry of ESCONI, it was identified as a rare  Tyrannophontes theridion Shram, 1969. From Wittry's book, The Mazon Ceek Fossil Fauna, "First discovered at Pit 11,  Tyrannophontes theridion was figured and described in 1969 by Shram. Subsequently, similar species were found preserved in the Pennsylvanian black shales of Iowa and Nebraska." Interestingly, nothing is mentioned of the black shales in Illinois. On a side note regarding the mysterious spiny, eel-shaped  Listracanthus that has eluded paleontologists for 150 years ,  a complete specimen has finally b
Read more

Pennsylvanian

Image
Trip to the Pennsylvanian edge of the Illinois Basin. Sunrise 6:30am Stop no. 1 was the Bond formation behind a cemetery near the border of Indiana. The rocks here contain a rich fauna, however I was mostly looking for rugose corals to make thin sections. Stop no. 2 was mostly for scouting for the black Mecca shales to find shark remains.
Read more

Water Levels

Image
I thought it would be fun to periodically post water level data, since the sea levels are rising. I'll mostly focus on Lake Michigan, Great Lakes, Atlantic ocean. Here are some pictures of disappearing Juneway Beach in Chicago and a link to an article here . 2019
Read more