Backyard Trip

[Missourian]

I'm close to linking together the various Cement City Limestone sections that I've described. There is one blank spot on the map that I'd like to fill in.

 

Between the thick section of Cement City in the city park shown here http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__view__findpost__p__285787 and the outcrops in the golf park here http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__view__findpost__p__302034 , there is a decent-sized creek that runs along the side of a highway ramp. The position, elevation and terrain all indicate a good chance of finding the desired layers.

 

On the way to the ramp, I stopped at a road cut to check out this cross-bedded limestone:

 

 

This is the top of the Argentine Limestone. We've already seen this bioclastic unit on the other side of the highway in a previous post at http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__view__findpost__p__281934 . On this side, though, the rock is relatively unweathered. I searched for fossils, but the stuff I found were all 'leverites'.

 

No fossils, but I found this tree amusing:

 

 

It looks like it's holding up the ledge with its roots.

[Missourian]

The presence of the Argentine here helps constrain the stratigraphic position of any units in the target creek, which is just a short distance away. I parked on the ramp and made my way into the drainage. On the bottom, the channel downstream was lined with concrete, so I made my way upstream.

 

Soon, I began to notice some limestone outcropping in the woods to the left. I suspected Westerville. The beds dip slightly to the north, so it wouldn't be long until I could check them out close to stream level. After a short distance, I spotted a fairly thick section of shale in the creek:

 

 

This has to be the Wea. Also, note the laminae, especially at top.

 

I crossed the creek and climbed up into the woods to take a closer look at the limestone. There was the trickle of a small creek flowing over the ledge:

 

 

Just to the left is this excellent exposure:

 

 

This appears to be an old quarry. It may have been utilized for road bed material when they built the nearby interstate.

 

I spotted these round nodules of pink chert in the bedding:

 

 

Yep, this is Westerville.

 

Now if the Westerville is present here, there could be some Cement City just above it. I climbed up over the ledge and followed the small creek, but I found nothing but a single bed of limestone:

 

 

This could be the bottom of the Cement City, but for all I know, it could be more Westerville. Not too far above this, the creek channel ended at a developed area.

 

So there seems to be no exposed Cement City in this immediate area.

[Missourian]

There are several road cuts along a section of freeway south of the big interchange I visited back in February: http://www.thefossil...post__p__305390 . This four-lane highway is straight, busy, and has narrow shoulders. Even the ramps are intimidating to stop at. So I picked a relatively quiet Saturday to examine the various cuts.

 

The first stop features one of the few exposures of Farley Limestone in the immediate area:

 

 

If you recall, we visited the Farley at the beginning of this thread. Ok, I'll recall for you : http://www.thefossil...post__p__278154

 

There is a bit of Island Creek shale exposed here. It gradually transitions into the limestone of the Farley:

 

 

The massive ledge is a cross-bedded oolite:

 

 

The ooids, along with deep weathering of the outcrop, have given the rock some interesting texture:

 

 

Ooids, up close:

 

[Missourian]

The rock is quite fossiliferous, but unfortunately, it is difficult to extract anything.

 

Some fossil debris:

 

 

Mollusks are plentiful. Here are a couple gastropods:

 

 

This cephalopod has been weathering out for several years:

 

 

The Farley is known for containing myalinid pelecypods, but I didn't see any here.

 

Some ooid-filled burrows are present:

 

 

I also found these 'tunnels':

 

 

I'm not sure if these are burrows or solution tubes.

[Missourian]

Speaking of solution tubes, there are large, dirt-filled tunnels near the top of the oolite. There are also some flowstone-like calcite deposits in places:

 

 

Above the oolitic bed is some sandstone:

 

 

This marine sandstone splits into slabs. Some contain trace fossils:

 

 

There is a second bed of limestone capping the unit, but it is not present here. I had to drive up to the next exit to see it:

 

 

The top surface is covered with Osagia:

 

 

I took this little plate home with me.

 

Above the Farley here is the Bonner Springs Shale and the lower part of the Plattsburg Formation:

 

 

A strat chart:

 

 

Soon, we'll move on to the next road cut....

[Missourian]

Back on the freeway, I passed by a few small exposures. One contained the rust-colored beds of the Spring Hill Limestone. Another looked like the tight bundle of beds that is the Captain Creek. I've seen them before in other places.

 

And then I beheld this:

 

 

As I zipped by, it was soon in my rear-view mirror:

 

 

Wow. Dipping beds.... Strata hardly ever dip like that around here. I then recalled the presence of a fault in the vicinity. Surely the tilt in these beds is related to it.

 

I also spotted some black, platy shale. This has to be the Eudora. If you recall ( http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__view__findpost__p__282418 ) , the only trace of this black shale I've manage to find was a couple fragments mixed into debris atop a barren surface of Captain Creek Limestone. Also missing from my 'inventory' is most of the Stoner Limestone. Previously, I'd manage to find only the upper few feet in a creek bed ( http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__view__findpost__p__305390 ) . It appears that most, if not all of the Stoner is present here.

 

Since I was going 60+ MPH, I had to hit the next exit and turn around. Once back at the cut, I stopped and systematically worked my way up the section.

 

The lowermost unit seen here is the Spring Hill Limestone. Only the top ten feet or so are exposed:

 

 

Some of the beds contain nodular chert. It is the gray stuff near the lens cap:

 

 

The Spring Hill again, and the overlying Captain Creek:

 

 

The covered area in between marks the Vilas Shale.

 

The Captain Creek juts up into the sky:

 

 

In Kansas, this unit is known for exquisitely preserved Enteletes brachiopods, but I didn't see any here.

[Missourian]

Moving along, we come to a complete section of the Stanton Formation:

 

 

This is yet another example of a transgressive-regressive group of strata that is typical of cyclothems of the area. The Captain Creek is the transgressive unit. The Eudora is the 'core' shale that marks the maximum extent of the marine incursion:

 

 

The Eudora is rather thick for core shales of the area. Here, it appears to be about four feet thick. The black, platy portion has the appearance of a stack of tar paper:

 

 

Here, jointing in the shale and erosion have combined to produce a repeating group of protrusions:

 

 

These black, platy shales are rich in conodonts. They can be spotted as glints of sunlight on the surface:

 

 

At another location in the metro, I found a couple large thylacocephalan carapaces in the platy shale:

 

[Missourian]

We now come to the Stoner, which is typical of Pennsylvanian regressive limestones:

 

 

The lower beds are thin and wavy, which may be indicative of phylloid algae:

 

 

A portion of the upper beds are bioclastic. Crinoid ossicles make up much of the fossil debris:

 

 

Note the orange color, and how it contrasts with the light gray of the rest of the unit. This helps one differentiate the Stoner from other limestones in the area. Other outcrops of Stoner miles to the west illustrate this consistency of appearance:

 

 

This color is due to oxidation. The limestone may have been exposed to the air prior to deposition of the overlying Rock Lake Shale.

[Missourian]

A stratigraphic chart of the dipping strata:

 

 

[Missourian]

FWIW, I updated the strat column for posts #153-155:

 

 

I drove by the cuts on the way to work to see if I missed anything.

 

First, I noticed several feet of Island Creek Shale exposed in the drainage ditch below the Farley. I must have been focused on the limestone. Or I was lazy.

 

Secondly, I didn't even notice a small outcrop of Argentine limestone across the street and downhill from the Farley and Island Creek.

Thirdly, I differentiated the lower Plattsburg Formation into its members.

[Missourian]

I recently scaled the highest hills to fill in the gaps in the upper part of the stratigraphic column. Now it's time to check the lowest valleys to find the 'missing' beds at the bottom. The big creek close to home contained the upper Winterset Limestone and a bit of the Bethany Falls, but after careful searching, the lower Winterset and a couple shale units were nowhere to be found.

 

I recently found a publication that mentioned an exposure of Bethany Falls Limestone in a small creek near the Missouri River Bluff. It's a just a bit outside of the area I've been searching so far, but it was worth a check. The stream flows through the center of an older, inner-ring suburb. Fortunately for me, a public greenway surrounds the creek for much of its length.

 

I started off with the upper section of the channel. After walking across a park to the edge of the woods, I immediately saw this:

 

 

The prominent overhang of black shale first caught my eye. That would be the Stark Shale. And better yet, there appeared to be at least a couple more units present. I walked along the outcrop and found everything from the upper Bethany Falls to the lower Winterset:

 

 

The Galesburg Shale is particularly well exposed here:

 

 

This claystone is mostly non-marine. There may even be a paleosol present here, but I couldn't discern it. Also, bits of Bethany Falls can be seen in the lower right. Above the Galesburg is the Stark:

 

 

Unlike the Galesburg, the black, platy portion was deposited during maximum depth of the sea. As the water shallowed, gray shale was deposited. This was followed by the limestone of the Winterset:

 

 

Using conodont faunas, some researchers think there was a minor re-deepening of the ocean during deposition of the lower Winterset. This is expressed by the dark band of shale near the top of the image.

 

So are any higher beds of the Winterset present? The only way to find out is to walk upstream....

[Missourian]

Continuing upstream, I didn't see any more Winterset. Instead, I found this:

 

 

Again we have the Galesburg and Stark, but there is something different here. There are a couple thin beds of limestone between the two shale units:

 

 

This is the Canville, which is the transgressive limestone of the Dennis Formation. Until today, I've never seen it. This bed is present in southern Kansas, but is mostly absent in the Kansas City area. When present, it is usually a half-inch limestone or a thin zone of calcareous shale. Interestingly, the bed is 8 inches thick here, while it is entirely absent just 100 meters downstream.

 

The limestone is impure. It is somewhat clayey, and contains some angular inclusions:

 

 

I'm not sure what these things are. I didn't see any identifiable fossils.

 

I continued up the creek, but soon came to a bridge. There were signs of more outcrops further up, but that section of creek wasn't on the agenda for today.

[cgodwin37]

Angular pieces might be chert or extraclasts, possibly a thin transgressive lag.

[Missourian]

On 4/9/2012 at 4:48 PM, cgodwin37 said:

Angular pieces might be chert or extraclasts, possibly a thin transgressive lag.

 

You can also see them on the bottom side of the upper Canville bed in the second image. The Canville is an odd duck....

[Missourian]

As I was unable to continue, I turned around and walked back down the creek. I eventually found some spotty exposures of Winterset high up on the steep slope:

 

 

The Stark Shale can be seen in the lower right, just above the horizontal, cane-shaped log. The big bed at the top looks like the massive, root-bearing limestone I've seen before, but I would have to climb up to be sure. It doesn't look like much, but scrambling twenty feet up this slippery slope was a bit harrowing, but that's the hand I was dealt.

 

The bundle of beds on the right looks like a big sandwich:

 

 

I followed the top 'bread slice' of the 'sandwich' leftward over to the clump of rocks in the foreground:

 

 

The area between these rocks and the massive bed is messy, but it appears to be mostly limestone.

 

The massive bed didn't show any obvious signs of root molds on its weathered face:

 

 

But I did find some on freshly broken surfaces, as seen at top-center:

 

 

Along with the roots, the yellowish color of the rock may be an indication of oxidation due to subaerial exposure relatively soon after deposition. Note how the matrix within the Linoproductus brachiopod in the lower left is more of a neutral gray. Perhaps the shell inhibited alteration of the sediment.

 

This Winterset exposure was spotty, weathered and treacherous. Sometimes, these are the funnest to piece together.

 

Not too far away, there is a massive chunk of Winterset that had slid down to the edge of the water:

 

 

An oil drum in the water (yuck) gives some scale. Note the good-sized tree growing right out of the top.

 

These slump blocks can fool field mappers. I know of at least one case where such a slump had been interpreted as a fault with fifty feet of displacement. This is in an actual publication. I won't mention names.

 

I continued on down the creek until I reached an impassable pool surrounded by dense vegetation. I would have to drive over to the next meander to find more outcrops.

[Missourian]

I made my way down to a public greenway adjacent to the creek and parked next to a bridge. As expected, I encountered some Bethany Falls Limestone:

 

 

This ledge-forming unit often makes nice little waterfalls. This is merely the first of a handful of little cascades that continue under the bridge.

 

The Bethany typically has the appearance of weathered concrete:

 

 

Can you tell them apart in the image? Hint: some of the stuff on the right is not rock. It is a bit tricky, but this distinctive appearance helps one identify it in the field.

 

I was ready to make my way up the creek, but a prominent outcrop downstream caught my eye. Along the way, a raccoon was frolicking in my path. I lost sight of him as I approached. Fortunately, he moved on to better things. And so did I:

 

 

Pollution stinks, but the tire on the right provides for some scale.

 

From what I can tell, only the upper third or so of the Bethany Falls is exposed here. Up close, some variations in the bedding can be distinguished:

 

 

There is medium-thickness beds near the water, nodular stuff in the middle, and slightly cross-bedded layers at the top. It kind of reminds me of the arrangement of the Cement City Limestone, even though the two units are drastically different in nearly all aspects.

 

There are some interesting mini-karst features in the cliff face:

 

 

There is one more meander of the creek before it enters the Missouri River flood plain. Judging by its appearance, I doubt there is much more to find strata-wise. I didn't feel like crawling through backyards to find out. Besides, there are more beds upstream to check out.

 

So back up the creek I went. Bethany Falls bedrock was exposed all along a long stretch. I eventually made it to the crumbly, nodular bed at the top of the unit:

 

 

This stuff seems to be riddled with holes. It is not as delicate as it appears:

 

 

This 'rotten' rock was an exposure surface relatively soon after deposition. As the Bethany sea drained away, the limestone was exposed to the elements until the overlying Galesburg shale was emplaced.

 

Fossil-wise, the Bethany Falls doesn't have much to offer. The only fossils of note are the Eowaeringella ultimata fusulinids that occur as a zone in the lower part that serves as a useful biostratigraphic marker.

 

As I was losing the Bethany Falls to the creek bed, I began to spot some Winterset outcrops up ahead. I'll have to make my way over to them.....

[Bullsnake]

I keep reading this thread over and over again, hoping something will stick and I'll recognize it. However, I think I usually hunt a different srata, so I'm still trying to figure that out!

You'd think if the Bethany Falls looks like concrete, they would have called that the Cement City. What were they thinking.

[Missourian]

On 4/13/2012 at 2:14 PM, Bullsnake said:

I keep reading this thread over and over again, hoping something will stick and I'll recognize it. However, I think I usually hunt a different srata, so I'm still trying to figure that out!

 

It is necessary to be aware where you are on the outcrop belt. The beds dip slightly to the WNW, outcrop in a general NNE/SSW direction and, as you can imagine, swing back and forth with the topography.

 

Note the thickness of the beds in relation to each other. For example, it is fairly easy to pick out the Westerville and Cement City Limestones from afar because they tend to be close to each other in outcrops. Smaller exposures with no stratigraphic context can be tricky, and a closer look is needed.

 

In your neck of the woods, the Lansing should be fairly prevalent. I would start by keying on the black shale of the Eudora, if possible, to get my bearings.

 

Quote

You'd think if the Bethany Falls looks like concrete, they would have called that the Cement City. What were they thinking.

The Bethany Falls is more like Cement Fortress.

[mikecable]

It is necessary to be aware where you are on the outcrop belt. The beds dip slightly to the WNW, outcrop in a general NNE/SSW direction and, as you can imagine, swing back and forth with the topography.

Note the thickness of the beds in relation to each other. For example, it is fairly easy to pick out the Westerville and Cement City Limestones from afar because they tend to be close to each other in outcrops. Smaller exposures with no stratigraphic context can be tricky, and a closer look is needed.

In your neck of the woods, the Lansing should be fairly prevalent. I would start by keying on the black shale of the Eudora, if possible, to get my bearings.

The Bethany Falls is more like Cement Fortress.

I'm guessing that your area is much different from mine. I read the Geologic Atlas of Texas, and see stratigraphic layers that can range from inches, and disappear, to layers that can be hundreds of feet thick. I'm doing my best to differentiate the Antler Sand from the Walnut Clay, much less the Comanche and Edwards limestone. I want to learn how to differentiate stratigraphy. Preferably without a microscope and thin sections.

[Missourian]

On 4/13/2012 at 6:13 PM, mikecable said:

I'm guessing that your area is much different from mine. I read the Geologic Atlas of Texas, and see stratigraphic layers that can range from inches, and disappear, to layers that can be hundreds of feet thick. I'm doing my best to differentiate the Antler Sand from the Walnut Clay, much less the Comanche and Edwards limestone. I want to learn how to differentiate stratigraphy. Preferably without a microscope and thin sections.

 

I think your beds are closer to the clastic wedge adjacent to the orographic belt in Oklahoma. The beds are similar on the other side in northern OK and southern Kansas:

 

 

The limestones and clastics are more 'balanced' in my area in KC. I prefer them that way.

[Missourian]

On 4/13/2012 at 2:14 PM, Bullsnake said:

I keep reading this thread over and over again, hoping something will stick and I'll recognize it. However, I think I usually hunt a different srata, so I'm still trying to figure that out!

You'd think if the Bethany Falls looks like concrete, they would have called that the Cement City. What were they thinking.

 

As seen near the Firefighters' Memorial in south KC, the Bethany Falls (middle) displays its typically neutral gray color:

 

 

Compare it with the subtly colorful beds of the adjacent Sniabar and Winterset.

[mikecable]

I think your beds are closer to the clastic wedge adjacent to the orographic belt in Oklahoma. The beds are similar on the other side in northern OK and southern Kansas:

The limestones and clastics are more 'balanced' in my area in KC. I prefer them that way.

Well aren't you the lucky ducky.

I like my stratigraphic layers huge, thick and sloppy. Sort of like Texas. I hope we get the chance to hunt the Pennsylvanian together some day.

[Auspex]

...I hope we get the chance to hunt the Pennsylvanian together some day.

I would surely like to tag along on that outing!

[Missourian]

On 4/13/2012 at 7:42 PM, mikecable said:

Well aren't you the lucky ducky.

I like my stratigraphic layers huge, thick and sloppy. Sort of like Texas. I hope we get the chance to hunt the Pennsylvanian together some day.

 

Ironically, the lack of limestone in the Texas column seems to allow for easy collecting of exceptional fossils. The Finis Shale is an example. Its fauna is similar to those in many of our limestones here, but the fossils are not locked up in fortress-like ledges. Assuming a suitable outcrop (eg. Jacksboro) could be found, that would make up for any difficulty in tracing the strata.

 

On 4/13/2012 at 7:45 PM, Auspex said:

I would surely like to tag along on that outing!

 

A 'Pennsylvanian Summit' would be fun.

[Kehbe]

A 'Pennsylvanian Summit' would be fun.

I will attend! Maybe we could get something going this summer! We are afterall centrally located! Maybe we get a thread started to see who might be interested and if there is enough interest to plan further!