A Trip To The Middle Creek Limestone (Pennsylvanian)

[Missourian]

The Middle Creek Limestone produces some of the finest fossils in the Kansas City area. Good exposures of this unit seem to be hard to find anymore. What collectors don't pick over eventually get covered with debris and vegetation. One exception seemed to be an outcrop that is in plain sight from the freeway. The problem here is that this is an interstate highway, so no parking is allowed. Before I knew the exposure was even worth looking at, I had to park at the nearest exit and walk a half mile with my tools and bags (and potentially walk back with a heavy load). As it turns out, it was worth it.

Before reaching the Middle Creek, I first examined the Sniabar Limestone at the base:

This bed is fossiliferous, but rarely is anything collectable. There are some interesting perforations in the lower bed here that may be due to burrowing:

No, the snake skin on the right isn't a fossil.

Above the Sniabar, we come to the Elm Branch Shale and the Middle Creek Limestone:

The shale sandwiched between the two limestone beds is my target for today:

Edited September 23, 2012 by Missourian

[Missourian]

A profusion of fossils covers the ground in places:

It is worthwhile to also check the shale slope below for fossils that rolled downhill. Even the blocks of Middle Creek that had tumbled down are sometimes covered with the fossil-filled shale:

Above the Middle Creek, the section is mostly covered. Further up the hill, a 40-foot cliff of Winterset Limestone taunted me. :

Edited September 23, 2012 by Missourian

[nala]

Nice place for hunting,thanks for sharing!

[Missourian]

My haul was productive, if typical. The most conspicuous fossils are bryozoans and brachiopods.

Meekella is conspicuous:

The one in the upper right is the largest I've ever seen.

Composita is just as common:

Also present are Neospirifer (top), Juresania (middle), and Derbyia (bottom):

These small Derbyia appear to have attached to a Neospirifer:

A large, inflated form of Derbyia is rarely found:

Edited September 23, 2012 by Missourian

[Missourian]

Even more common are the bryozoans. Included are the branching types Tabulipora and Rhombopora, the encrusting Fistulipora, and various fenestrates.

Tabulipora and Rhombopora:

Rhombopora has pores arranged in neat, diagonal rows. The pores of Tabulipora are more irregular in arrangement. A few of the pieces near the bottom have sponge borings.

Fistulipora:

The branching forms are probably layers of encrustation on Tabulipora twigs.

This Fistulipora resembles Swiss cheese:

This piece features Tabulipora, Fistulipora, and a tiny attached form (probably Thamniscus):

Edited September 23, 2012 by Missourian

[Auspex]

These small Derbyia appear to have attached to a Neospirifer:

I like 'em all, but this one is very appealing!

[Missourian]

Crinoids are present, but don't stand out. Only rarely are calices and whole crowns encountered.

I did pick up quite a few stems:

And a few calyx plates of Aglaocrinus, as well as a stem with some severe burrowing:

Echinoids are pretty rare. These are from Archaeocidaris:

[Missourian]

I like 'em all, but this one is very appealing!

Me too.

I thought they were a chance occurrence, but then I thought perhaps they attached to other shell as juveniles.

[Missourian]

Most prized of all are the hash plates.

Most of the time, the fossils have a bluish color:

Many of the brachiopods here, especially the chonetids, are purple:

Some more purple brachs:

The large clam is Astartella.

Mollusks aren't as well preserved as the brachiopods. Here, mollusks have a rusty color:

Here, a Neospirifer is lonely among a crowd of Derbyia:

I was hoping to find some nice, large plates with many different types of brachiopods, but none were forthcoming.

[squalicorax]

Really quality brachs. Those hash plates are nice.

[CH4ShotCaller]

I was foaming at the mouth looking at the shale between the limestone layers. Nice report!

[Auspex]

...a stem with some severe burrowing:

Another highly interesting specimen! Look how "calloused" it is!

[moahunt1]

I like the groupings..... Looks like a fun trip!!!!

[glacialerratic]

Above the Sniabar, we come to the Elm Branch Shale and the Middle Creek Limestone:

What CH4ShotCaller said....

[trilobiteruss]

NIce collection and good pics of the geology, thanks for taking us along on this virtual field trip!

[Archimedes]

Nice Pennsylvanian Fossils and Outcrop pics thanks

[Missourian]

Thanks everyone for the comments.

I just cleaned most of the mud off a larger hash plate:

This one is fairly representative of the many slabs that can be found in the Middle Creek.

[nala]

Very nice slab!