Jump to content

Missourian

Recommended Posts

Next up on my strata recon agenda was a park containing a half-mile-long section of creek, which is upstream from the Wea-Westerville cut banks shown in this post: http://www.thefossil...post__p__283768

 

My goal today was to find a decent section of the Chanute Formation and some Cement City Limestone. Soon after I entered the woods on the lower end, I came across this:

 

post-6808-0-07076500-1327392182.thumb.jpg.bce7f4879a140d07239bf6c825bf271c.jpg

 

Pretty good so far. This is the lower part of the Cement City, with a little Quivira Shale below the two-foot-thick slab. Although there were bits of the productive beds present, there weren't too many fossils to be found. I did spot this huge Echinaria valve on one of the massive slabs:

 

post-6808-0-02160100-1327392196.thumb.jpg.937bc402135403e97ce3d348f6ddf3a0.jpg

 

After this, I continued a bit up stream. I soon found a second exposure:

 

post-6808-0-75344600-1327392217.thumb.jpg.6047b4ecabf0c411e97bfcfb7bbfa37f.jpg

 

Note the deposit of loess above the limestone.

 

The stratigraphy of the Cement City in these exposures is basically the same as it was at the City Park a couple miles to the north, as described in this thread: http://www.thefossil...post__p__285787

 

The bioclastic 'cap rock' is present:

 

post-6808-0-48634100-1327392404.thumb.jpg.74b225e07a59428551d35464fd0d69ba.jpg

 

'Cap rock'...... No pun intended. :)

 

The underlying nodular layer is here as well:

 

post-6808-0-78444800-1327392263.thumb.jpg.0269ee769613ed8bb2354e7ac7bf996f.jpg

 

This nodular stuff is richly fossiliferous. Many brachiopods are present:

 

post-6808-0-07470300-1327392423.thumb.jpg.a99e324327028d0259e72b03c6005d35.jpg

 

I will have to return here when I have more time.

Context is critical.

Link to comment
Share on other sites

Further up, the massive base of the 'cap rock' forms a bench in the creek bed:

 

post-6808-0-31769700-1327392671.thumb.jpg.786f935f6274eb45827d0dce8b9b1088.jpg

 

And at last, I found what I've been looking for:

 

post-6808-0-97002900-1327392682.thumb.jpg.8f34b1fe83b38ce581acc3ea3b144e6d.jpg

 

Above the top of the Cement City, we can see a beautiful section of Chanute ahead. Lets move a little closer:

 

post-6808-0-50003500-1327392694.thumb.jpg.ffba73f96cab2bbb7091f6ec403c5b0f.jpg

 

Ok, we have perhaps eight feet of shale and claystone, with five to six feet of thin-bedded, calcareous sandstone, and more shale further up. The top of the Chanute is marked by the bed of Paola Limestone in the upper right.

 

A bit closer to the shale, claystone and sandstone:

 

post-6808-0-61401300-1327392710.thumb.jpg.e7c8ae4babc5f39444946e8e6d636f13.jpg

 

The lower part of the Chanute is covered with fine shale debris from above, but it is likely all mudrock.

 

The sandstone here is thicker and more developed than anywhere else I've seen it. Some of the slabs are full of trace fossils. The ones I saw were a bit weathered:

 

post-6808-0-75143800-1327392725.thumb.jpg.bda2cd5cd93f46746290c507b313a466.jpg

 

As this cut bank is perhaps twenty feet high, I haven't quite yet figured out where to look for fresh slabs.

Context is critical.

Link to comment
Share on other sites

Higher up in the section, above the mostly covered shale of the upper Chanute, we can see a complete section of the Iola Formation:

 

post-6808-0-41181800-1327392835.thumb.jpg.505c2d7c35f05c562faaada590a1e1bd.jpg

 

As you can imagine, I had to climb up to check it out. Here is the Paola Limestone, Muncie Creek Shale, and Raytown Limestone:

 

post-6808-0-84776900-1327392849.thumb.jpg.0ef90743cec54bcdc741c4adf6586f92.jpg

 

And here is the Paola and Muncie Creek up close:

 

post-6808-0-03554400-1327392870.thumb.jpg.e529945f95c71fae9d19db9b81a09478.jpg

 

I didn't spot any concretions in the shale.

 

A small side valley just upstream likely has more outcrops, but I didn't have time to check it out. A little further up, I found a second cut bank with some Chanute:

 

post-6808-0-80670400-1327392882.thumb.jpg.b2439a96f36759a680b730720d19adf7.jpg

 

As I made my way up, I found a second large cut bank with some more Chanute and Iola. Here, the sandstone beds are at water level:

 

post-6808-0-97833600-1327392898.thumb.jpg.773d06c7c395e490b17a07e787f682eb.jpg

 

Note the large load casts to the left of the falls. Here they are closer up:

 

post-6808-0-64417900-1327392912.thumb.jpg.d7853ea06effef41918c54cd069ff020.jpg

 

Load casts form when the extreme pressure of overlying beds causes the still unconsolidated sand to flow. In this case, large blobs have squeezed down into underlying beds in 'lava lamp' fashion:

 

post-6808-0-38428100-1327392945.png.7d31da554d35fcf4798437f40d84ec54.png

 

At this point, the clock ran out and had to make my way back home. I will return in the near future....

Context is critical.

Link to comment
Share on other sites

That's a very indepth study you are doing.. I enjoyed

seeing the adventure...

What a love of geology you must have..

Welcome to the forum!

Link to comment
Share on other sites

Mind if we call you professor? :)

Incredibly well documented and described! Thank you for these posts!

Link to comment
Share on other sites

Thanks everyone for the comments.

 

I've always enjoyed peeking around that next corner....

 

That large exposure of Winterset Limestone I beheld in the little creek opened my eyes to the possibilities. Now every time I see a stream in the woods, I think of all the outcroppings -- and potential fossils -- that could be present.

Context is critical.

Link to comment
Share on other sites

Intrigued by the variability of the bedding within the Cement City Limestone, I checked out a couple exposures along the nearby interstate highways.

 

The first cut is on an exit ramp:

 

post-6808-0-80962300-1327796192.jpg.ed7fc2518d82f79e5dfb661d5eb2dc52.jpg

 

It is a mile south of the creek exposure shown here http://www.thefossil...post__p__296556 . It is basically two ledges with some soft stuff in the middle. The lower ledge is probably the same as the one in a couple other exposures we've seen. Up close, it appears quite dense:

 

post-6808-0-19681800-1327796235.thumb.jpg.19bbf0ddc3f657b8d5c08d6cbbdcd8bf.jpg

 

Above that, about two feet of the interval is covered. It probably consists of interbedded thin limestones and shales. Higher up, we come to the upper ledge:

 

post-6808-0-90113700-1327796252.thumb.jpg.f30f8ae024fdc7496c9b1f4e45cc1342.jpg

 

It is similar to the lower one, but it has some shale partings. Fossils could be found along the seam near the top. This Caninia torquia horn coral clinched the id of these beds as Cement City:

 

post-6808-0-93020900-1327796272.thumb.jpg.21aae671f3c677b93de6eb7a35bc590b.jpg

 

In one spot, a block of the upper ledge slid down, and the top slab slid off even further:

 

post-6808-0-81603000-1327796299.thumb.jpg.bc5a3b428a173f74c5c433a16c756c7f.jpg

 

This exposed the bedding plane of the top shale parting. There were many brachiopods present, but their preservation was rather poor. I did find this Echinaria with some interesting detail:

 

post-6808-0-25329900-1327796322.thumb.jpg.7da3e2fa07cdc1c80c39173d2a6a8d20.jpg

 

(Indy, what's the name of these swirly things again? :) )

 

The nodular bed and the bioclastic 'cap rock' that we've seen in other exposures are not present here. They may either be covered or missing altogether.

Context is critical.

Link to comment
Share on other sites

About three miles to the west, there is this cut on an entrance ramp:

 

post-6808-0-55248600-1327796444.thumb.jpg.2b8e0de891fd55f1c4fdf64c9e2cb319.jpg

 

The presence of concrete storm drainage ditch above may help keep this exposure free of debris. The gray bed near the middle appears similar to the bioclastic 'cap rock':

 

post-6808-0-18341700-1327796474.thumb.jpg.459bd5747d782491f9c97b0739675746.jpg

 

It appears to be made up of crinoid debris. Higher up is a reddish micrite that is slabby in the lower part:

 

post-6808-0-28282800-1327796508.thumb.jpg.b0e4dacf45411c62312d632e0d20143c.jpg

 

Just to the left, the slabby stuff almost appears nodular:

 

post-6808-0-58464400-1327796548.thumb.jpg.750fa5bb51b59726da65a6a5d4354676.jpg

 

The uppermost bed here contains many Composita brachiopods, myalinids, and crinoid fragments:

 

post-6808-0-48337700-1327796592.jpg.5102836cdaf393dc49c9fc7a6e82ef89.jpg

 

I didn't find any Caninia here today, but I did collect this guy several years ago:

 

post-6808-0-89867400-1323555506.jpg.63945f164e810224ecc9384b20baf608.jpg

Context is critical.

Link to comment
Share on other sites

As you travel further south, the Cement City becomes a massive ledge of limestone with little or no shale partings, as seen near downtown Kansas City, Missouri:

 

post-6808-0-16148300-1327796789.jpg.b1395a9bf4dd761d1dbb2e3924d21287.jpg

 

(Borrowing a photo of yours, Kehbe, if you don't mind…. :) ).

 

A couple miles to the southwest, along I-35, it is still a massive ledge:

 

post-6808-0-34073500-1327796819.thumb.jpg.1ef6856c959509b37ae490613f3623f6.jpg

 

This is the character of the Cement City over most of the KC area. The shale beds are present only in spots north of the Missouri River, as far as I've seen.

Context is critical.

Link to comment
Share on other sites

On 1/28/2012 at 8:02 PM, Bullsnake said:

Sorry, I'm not Indy, but they're beekites.

 

Thanks. All I could remember at the time was that they had a name that sounded something like "skittles" and that Indy had linked to a picture of them on his site.

Context is critical.

Link to comment
Share on other sites

We need to create the Sir Roderick Murchison Award, and name you to it; this is wonderful content!

"There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant

“Try to learn something about everything and everything about something.” - Thomas Henry Huxley

>Paleontology is an evolving science.

>May your wonders never cease!

Link to comment
Share on other sites

An updated master stratigraphic chart:

 

post-6808-0-86044000-1328517622.thumb.png.813aecb8e5f37f10f2be3bab86f200ae.png

post-6808-0-31948900-1328919980.thumb.png.cdba14887e5da38ec058e20ef0f5d780.png

 

It is divided into two parts to avoid the 2500-pixel image limit.

Context is critical.

Link to comment
Share on other sites

I second that motion.

A nice little guidebook could be made of this. Wish I had such a thing for my area.

Edit: Dang, you snuck that in there fast, I thought my reply would appear right below Auspex's! ;)

Edited by Wrangellian
Link to comment
Share on other sites

Something was bugging me about the Cement City Limestone outcropping at our neighborhood lake. To recap, I first described it here: http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__view__findpost__p__279541 . Here's my original image of the outcrop:


post-6808-0-96476100-1321905161.jpg.633954e949005a39a7aed194e3b6efc4.jpg.dd24f082c27a2fabc028ff7e4e6ab92e.jpg

At other nearby exposures (eg. here: http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__view__findpost__p__285789 and here: http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__view__findpost__p__296556 ) there is a few feet of nodular limestone near the top of the unit. Yet at the lake, the rock at the same level appears to be solid limestone. Because blocks were stacked at the top of the artificial waterfall, I started to have doubts about the nature of what I thought were the upper beds.

So I did what anybody would do. I walked over to the top of the falls and scrambled down as far as I could go. I reached the top part of the Cement City here:


post-6808-0-72623000-1328690425.jpg.dacbe94ed3644a9a4af2eb038d437e46.jpg

As you can see, this is deeply weathered limestone. It most likely is in its original position. It also appears to be made up of fossil debris, which is consistent with the upper bedding at other localities. I wanted to investigate further, but it was getting late and the lighting was not favorable to do any more work.

A few days later, the sky was overcast, which is ideal for photographing rock strata (I'm getting to like cloudy winter days.... :) ) To start out, here is a view of the entire exposure:


post-6808-0-35239500-1328690464.jpg.593cfdce225391495076002652adbb3b.jpg

After taking yet another look at these strata, I could finally tell that the thick bedding was indeed natural. And it was radically different than the nodular stuff that occurs nearby.

Closer in, we can see the bleached area of the currently dry falls, and some more bedding to the left:


post-6808-0-56034100-1328690483.jpg.f2e6f85bf935edceafa77d5217363faa.jpg

This appears to be a nearly complete section of the Dewey Formation, minus the black shale at the very base. The next thing to do was to gingerly work my way around the slope face itself. As it was lightly misting, the surface conditions were muddy if not treacherous, but that goes with the territory.

I started out at the bottom part of the exposure. Speaking of treacherous, the ground along the waterline was *very* muddy. I would sidestep along, and then KERPLUNKSH. It was basically 'quickmud'. The geese like to nest under the limestone here, but at least they were still out somewhere fighting over the squatting rights :)

Starting at the bottom of the section, I examined the two feet or so of Quivira Shale that was exposed:


post-6808-0-00316200-1328690547.thumb.jpg.19e992e321dc17da3a37c422d54e5ae3.jpg

It is basically a blocky, olive-colored shale. Some large chunks show mottling that may be traces of bioturbation:


post-6808-0-72086300-1328690561.thumb.jpg.59d096ba6a14133613c2cb6f8e8ba04e.jpg

Context is critical.

Link to comment
Share on other sites

The lower half of the Cement City was fairly easy to reach:


post-6808-0-84488100-1328691122.thumb.jpg.cda5cff569cdb4be11a438ba3e273db0.jpg

The lower ledge forms a prominent overhang along the entire exposure. Up close, it appears to have some crinoid fragments:


post-6808-0-46493200-1328691136.thumb.jpg.0144432bcd1aed8dd878598f8132c0be.jpg

Above this ledge is some interbedded thin limestone and shale that is nicely fossiliferous when it is well exposed.

Near the top of the slope is a bundle of thin limestones that forms a thin but noticeable ledge in the outcrop. I climbed up to get a better view:


post-6808-0-82702300-1328691149.jpg.9c6f0072cb9cf9caf2314a913719f921.jpg

These beds (a.k.a. 'middle beds') mark the middle of the Cement City. These slabs contain crinoids, brachiopods, and bryozoans:


post-6808-0-30981900-1328691178.thumb.jpg.1c37f8062f7006564645b99f2a7f5dbf.jpg

I found a few specimens Caninia and Kozlowskia on this slope, but I'm not sure from which beds.

To see the beds further up, I had to precariously swing like a monkey from some trees growing out of the cliff face:


post-6808-0-92408700-1328691219.thumb.jpg.35f96c071c417ef60a09158404214c09.jpg

This shows the 'middle beds' at bottom, a thin bed of shale, and the medium-bedded limestone that I was wondering about earlier. Looking at the latter up close, I could see that they are made up of crinoid debris:


post-6808-0-39588400-1328691236.thumb.jpg.aff4c6bbd3c27e16ace74784e2089148.jpg

There seems to be some slight cross-bedding.

I would think these are part of the bioclastic 'cap rock'. Perhaps the thickening of this facies marks a displacement or erosion of the nodular stuff. Or maybe the rock types transition into each other. Beds at the highway ramp exposure previously described here http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__view__findpost__p__297924 seem to show such a transition:


post-6808-0-55248600-1327796444.thumb.jpg.081071fc62db3b19b844a57756e85db7.jpg

Context is critical.

Link to comment
Share on other sites

My latest foray was more challenging than usual, though it did start out simple enough. While scanning the landscape of a large city park a few miles to the north, I spotted a really large rock outcropping in the east fork of the big creek we've seen before. As I've been seeking a northern outlier of the Cement City Limestone, I had to take a look.

 

The creek flows along the edge of a municipal golf course. Because I had to walk around a driving range, I had to leave my backpack in the car. I didn't want anyone thinking I was collecting (i.e. stealing) balls. :) I eventually reached this:

 

post-6808-0-78312100-1328861215.thumb.jpg.d04fdc720faf88e96ed8ff536221e696.jpg

 

This is an amazing waterfall, but I was drawing a blank as to the id of the unit. There were no reliable stratigraphic markers to be found. The possibilities included the Winterset, Westerville, Cement City, or even the Raytown.

 

These orangish beds, as well as the lack of chert and shale partings, made me doubt that it could be the Winterset:

 

post-6808-0-92261500-1328861231.thumb.jpg.08fbe761d92d4bbe82ba2df568eed557.jpg

 

I walked downstream a bit and came across this nice cut bank:

 

post-6808-0-19709300-1328861248.thumb.jpg.e159a14d970c91011fcb9de3033d4100.jpg

 

These strata look somewhat similar to the Raytown Limestone, but that would seem to be out of place here. The Raytown is present nearby in a highway exposure (see: http://www.thefossil...post__p__281792 ), but it is high up on the hillside. The appearance of these beds ruled out the Cement City. So that left the Westerville, which can be quite variable in thickness and lithology.

 

As I walked along the stream, I encountered plenty of outcroppings. But there was a problem. They were exposed in the floor of the channel beneath the water, but not so much in the banks. It's as if something had scoured off all the bedrock before the banks were put into place. There is a good-sized flood plain here, so that sounded reasonable. Whatever the reason, this made keeping track of the layers very difficult. I assumed that I was seeing the bedding planes within the top of the Westerville. After a third of a mile or so of this off-and-on, subaqueous pavement, I finally stumbled upon this nice laminated limestone:

 

post-6808-0-92081400-1328861306.thumb.jpg.d5c4c69de3bc13bf641a067c0013108f.jpg

 

Such laminae often occur in peritidal deposits in the tops of some Pennsylvanian regressive limestones, so they weren't unexpected. When I broke off a piece of this really dense stuff, it turned out to be a very fine-grained rock. I didn't see any sign of fossils.

 

As I was running out of time for the day, I had to make my way back. Along the way, I noticed some rock bedding in a clearing. As I made my way up, I encountered an old quarry with this ledge of Raytown Limestone:

 

post-6808-0-65959100-1328861333.jpg.20f6878aba2557551749c95780284a62.jpg

 

Being only thirty feet or so above the creek, it helped to constrain the level of the other strata.

 

On a sour note, the quarry floor exposure was inches away from the Muncie Creek Shale. If it had been hit right, I could have spent the next few months collecting buckets of concretions. Oh well....

Context is critical.

Link to comment
Share on other sites

The next day, I parked at a spot further upstream and made my way down the creek. Right off the bat, I came across an exceptional exposure of the light blue-olive, clayey limestones and calcareous shales within the Cement City that I've been calling the 'productive beds':

 

post-6808-0-19246000-1328861491.thumb.jpg.608f97143f0f1bda740c5b58dd7be146.jpg

 

Not only was it well exposed, but wide areas were stripped off. Just in the few minutes I spent there, I found brachiopods, bryozoans, and crinoid fragments. Because I've found fossils in these beds like the ones shown here http://www.thefossil...post__p__284178 , I put this spot on my follow-up list.

 

Another, close-up view of the shale-limestone mix:

 

post-6808-0-71754100-1328861506.thumb.jpg.42ba43bc383ed7ec83a8d4794f9a719c.jpg

 

On the other side of the creek, there was more blue-olive stuff capped with an interesting bed of limestone:

 

post-6808-0-12146300-1328861529.jpg.e063e2c74e29b4c0ff71a9f2e84227b0.jpg

 

Notice the little stalactite-like knobs hanging from the base of the bed. These are burrow casts exposed in stark relief after the underlying shale had been washed away. Also fascinating were the these slabs stacked like shingles:

 

post-6808-0-53684300-1328861549.jpg.dc2d5c674c45a43dd48471f0fc83a18b.jpg

 

These are part of an old gravel deposit of the creek. The slabs may point to more limestone further upstream. Ok, time to move on....

Context is critical.

Link to comment
Share on other sites

After more bedding along the floor of the creek, I came across a huge jumble of limestone boulders and slabs that had been plucked from the creek bed. This is similar to the 'fossil' gravel deposit seen earlier. Many large slabs featured the burrow casts similar to the ones shown earlier.

 

A little further down, I begin to encounter a number of large slabs with desiccation cracks in the surface:

 

post-6808-0-97555700-1328861702.thumb.jpg.b6a300b3ba14f0715ff90d0566d962fa.jpg

 

Wow, I'd really like to find some of these in situ. Are these in the laminated beds? Why yes, they are:

 

post-6808-0-51391900-1328861799.thumb.jpg.c9692fc5df2806d00c3c3e2d42fdef45.jpg

 

Laminae, mud cracks, and a lack of fossils are classic indicators of tidal-flat deposits. This had to be the top of the Westerville. Because they were present here but not in the pile just a couple hundred feet upstream, I figured that they were stripped from the bedrock beneath the pool between the two spots.

 

The above image also demonstrates that looking at the creek gravel can give you a lot of clues about the local stratigraphy. Besides the laminated bed, there are also large chunks of the blue-olive beds that would have tipped me off to upstream deposits if I had approached from downstream. The particularly fossiliferous piece of limestone in the lower left is tantalizing. On the other hand, the chunk of Sioux Quartzite on the right points to the possibility that some rocks found here could have traveled many miles from their points of origin.

 

These cobbles and boulders are pretty, but I was anxious to find some more bedrock. I would soon get my wish:

 

post-6808-0-59909800-1328861822.jpg.556d0771cf585a17e86fa6884b1f7491.jpg

 

This bed looked familiar. It has the appearance of the lower ledge of the Cement City. But how could it be, considering that there was some Westerville exposed in the creek between it and the Cement City further up? Or so I thought this ledge was Cement City. I needed more information.

 

I got it when I plucked this black shale from beneath the ledge and the water:

 

post-6808-0-60387300-1328861894.thumb.jpg.0d39d32716bcb525adb4b978f1768169.jpg

 

This must be Quivira Shale. So this is indeed the Cement City. So what's further downstream? About a hundred feet away, I found this limestone poking out of the water:

 

post-6808-0-68968200-1328861872.jpg.c60ef7cffc066ef5020a6b7f54f37435.jpg

 

This had to be the underlying Westerville. The Quivira and Nellie Bly Formation seem to be quite thin here. A few hundred feet further down, I arrived at the exposure where I originally saw the laminated beds.

 

This is all fine and dandy, but how did the stratigraphy get all scrambled up? I took another look at the lower ledge:

 

post-6808-0-86919900-1328861915.thumb.jpg.59df3110d98f6176e5968006ef520ff2.jpg

 

Note that the beds are dipping slightly to the left. So there may be a small fold that runs parallel to the general direction of the creek. At this spot, the creek encounters the Cement City near water level as it meanders into the direction of the dip. In other words (or no words), it would look something like this:

 

post-6808-0-45649200-1328864868.png.e4cb72a2cc7f0c5feeb02591714003bb.png

 

So that ties up the loose ends for now. Next time, I'd like to find the remainder of the Cement City further up the creek. Stay tuned.... :)

Context is critical.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...