Backyard Trip

[Auspex]

Nice job!

I'll bet those blank spots are just like empty holes in a penny album to a coin collector...

[Bullsnake]

Is there any special characteristic to identify the Bonner Springs shale?

[Missourian]

On 7/11/2012 at 8:09 PM, Auspex said:

Nice job!

I'll bet those blank spots are just like empty holes in a penny album to a coin collector...

 

The biggest empty holes are the no-trespassing areas. Sometimes, it takes only one look.... (not that I would.... )

[Missourian]

On 7/11/2012 at 8:14 PM, Bullsnake said:

Is there any special characteristic to identify the Bonner Springs shale?

 

The Bonner Springs can be identified mainly by location and stratigraphic context. The shale itself doesn't really have any distinguishing characteristics. The Osagia zone at the top of the Farley helped me in this case. The Spring Hill above, with its thick, rust-colored bedding, can be helpful as well.

[Missourian]

When it's 100 degrees outside, the only thing to do is do some strata recon in the shade....

 

This time, I checked out the woods surrounding a small city park to the west. After finding a decent dirt path, I made my way down the slope and immediately came across this:

 

 

Right away, it was evident that the layers were dipping to the north or east. Only a half mile to the west are these dipping strata here http://www.thefossil...140#entry317607 . They most likely are all associated with a known fault in the area.

 

Based on the location and apparent elevation, I figured I was most likely dealing with one of the Lansing Group limestones. The style of bedding seemed to be more like the Stoner, but I wasn't sure.

 

The lower beds up close:

 

 

The upper beds stretch across the creek:

 

 

The dip is really pronounced with these. A pinkish orange color is similar to the top of the Stoner:

 

 

Twenty feet or so up the slope, as well as further upstream, some sandstone is present. This piece contains some poorly-preserved plant fragments:

 

 

This is most likely the Tonganoxie Sandstone, which fills valleys cut into the underlying strata. I examined some a few months ago: http://www.thefossil...100#entry305391 .

 

Nearby, a substantial spring flows from the side of the hill. I figure the water is discharging from the base of the sandstone.

 

This area has some potential, but it is currently a dense thicket. I'm looking forward to the cooler months when much of the underbrush has died off.

[Carcharodontosaurus]

Sounds like a great trip. Finding fossils in a backyard must be incredible. I wish I could find my own fossils that easily.

Edited July 22, 2012 by Carcharodontosaurus

[Missourian]

On 7/21/2012 at 8:35 PM, Carcharodontosaurus said:

Sounds like a great trip. Finding fossils in a backyard must be incredible. I wish I could find my own fossils that easily.

 

It takes a lot of walking, as my 'backyard' is quite big.

[RomanK]

So where are the fossils, you may ask? A few plant fragments were mixed into the conglomerate:

These are nothing compared to the fossil plants found in the Tonganoxie near Ottawa, Kansas....

Neuropteris:

I would say Alethopteris instead Neuropteris...

Edited July 27, 2012 by RomanK

[RomanK]

Since my local excursions have been turning up empty fossil-wise, I will tide you over with some specimens from the Winterset Limestone found around the Kansas City metro....

And in a few isolated spots, ferns can be found. This is Pecopteris:

Well, that's all for now.

My opinion - Mariopteris instead Pecopteris.

Edited July 27, 2012 by RomanK

[Missourian]

About a month ago, I drove through some neighborhoods a few miles to the northeast to see if I could find any new rock exposures. Normally, there isn't much to be found in developed areas, but on that day, I stumbled upon four outcrops in close proximity to each other. As there was no convenient (or legal) place to park, not to mention that the lower atmosphere was a blast furnace that day, I had to add them to the to-do list.

 

With clement weather in store for the afternoon, I decided to investigate the outcrops. I had to park a mile away. But then, I usually walk a few miles a day for exercise anyway.

 

At the first stop, there was a single thick bed of limestone. It looked as if they were separate blocks that were carefully set in place:

 

 

There are almost no bedding breaks in the massive limestone:

 

 

The rock itself is extremely tough. I had difficulty even finding a loose piece to take with me.

 

Fossils include Osagia, brachiopods and fenestrate bryozoans. Osagia was readily visible on the relatively fresh surfaces:

 

 

The presence of abundant Osagia, as well as the unique bedding, led me to preliminarily id this as the upper Farley Limestone.

 

Below the ledge, there are some thin slabs that had broken away. These contain productid brachiopods:

 

 

Further up the slope is about twenty feet of shale with some sandstone:

 

 

It was mostly covered. With the Farley below, this should be the Bonner Springs Shale.

 

At the top is what appeared to be a bed of limestone:

 

 

I'm not sure if this is the bottom of the Plattsburg Formation in situ, or remnants of the overlying unit that remained on the hill top.

[Missourian]

Not too far away, I walked into a residential construction site that had extensively exposed shale. Based on the context of the strata I'd just seen, I figured this is more Bonner Springs.

 

At first glance, it is a typical thick shale with thin zones of sandstone:

 

 

When I came closer to the beds at the top, I was amazed by some crazy, festoon-like bedding near the top:

 

 

I figure the little troughs were scoured into the mud, and then later blanketed with a thin veneer of sand and covered with more mud. As this process was repeated again and again, it resulted in this seemingly irregular network of sandstone laminae.

 

Since the only fossils present were minor traces, I moved on up the slope. At the top, there are jumbles of blocks scattered about. Some contain Composita brachs:

 

 

These boulders are likely Plattsburg, but since there were no bedrock outcrops, I can't know for sure.

[Missourian]

Ok, moving on....

 

A couple blocks up the street, I reached this outcrop of limestone that was tastefully worked into the landscape:

 

 

It looked like part of the Plattsburg, possibly the Merriam Limestone. Up close, the rock face is pretty, but there weren't any fossil to collect (nor that I'd wanted to).

 

I then walked a short distance to the last exposure. I made my way up approximately thirty feet of mostly covered shale to reach the exposed strata:

 

 

The first thing I encountered was some nicely fossiliferous shale:

 

 

The fossil assemblage was dominated by well-preserved Derbyia, along with some Composita and a few other pieces:

 

 

I'd like to spend some more time here at a later time.

 

Above that, a thick sequence of limestone was separated into two ledges. The rusty color and medium to thick bedding almost certainly make it the Plattsburg.

 

A large block, which is identical to the manicured ledge we saw earlier, is covered with fossiliferous shale, including some filled burrows:

 

 

Apparently, this is a block of Merriam that was flipped over during excavation, exposing the underside. A bed of buff colored shale a little higher up in the rock face is probably the Hickory Creek Shale:

 

 

When I checked the upper section above, I spotted these bands of chert, which confirms this as Spring Hill Limestone:

 

 

As is usually with the Spring Hill around here, there werent' too many fossils to find, so I climbed back down to the Bonner Springs to pick up a few more Derbyia.

[Auspex]

...The fossil assemblage was dominated by well-preserved Derbyia, along with some Composita and a few other pieces:

...

Gotta' love rotten shale

Very cool ramble; thanks!

[Missourian]

The severe drought conditions have had quite an effect on our neighborhood lake.

 

Here's a comparison of the rocky shoreline from last winter and now:

 

 

The drop in the water level is only about two feet, but it has exposed quite a bit of Westerville Limestone, which is part of an old quarry face. Some more:

 

 

Overall, this bed is eight feet thick, but I don't think the drought will last that long....

[Missourian]

As the water recedes, the grass retreats into the lake bed.

 

[Missourian]

On the same day as http://www.thefossil...220#entry343457, I also visited some cuts along the interstate a mile to the east:

 

 

I must have passed by this exit hundreds of times, but I'd never bothered to stop. Due to the tight bundle of thin beds, I figured it was Argentine Limestone. Recently, I began to have doubts. Its location and elevation seemed too high for the Argentine. Also, the lower beds didn't look right. The Stanton Formation seemed like the best bet.

 

I parked at the ramp and surveyed the scene:

 

 

As I approached the upper ledge, I spotted some patches of black shale:

 

 

This is the Eudora, since no other black shales are anywhere close to this level. That means the top limestone is the Stoner:

 

 

This rock is normally light gray when fresh, but since this cut has been here since perhaps the Eisenhower Administration, the surface is almost black and deeply weathered. The rock is riddled with solution cavities. Some of these could be considered to be small caves:

 

 

Some pieces contained many fusulinids that appeared to come from the top. Since the upper surface appeared to be scoured free of soil, I would have to climb up on top after checking the lower beds.

[Missourian]

Below the Eudora is a fine section of the Captain Creek Limestone:

 

 

Fossils here seemed to be limited to small shelly fragments:

 

 

Below that is a covered interval of Vilas Shale and the top of the Spring Hill Limestone:

 

 

As promised, I climbed up to the top of the Stoner. There is a profusion of fusulinids:

 

 

The ground looked like my parched lawn after I made a futile attempt at overseeding.

 

These are by far the largest concentrations I've seen in the Kansas City metro. I took a few pieces home with me:

 

 

Edit: these fusulinids probably are Triticites primarius.

 

Mixed in with the fusulinids are many Archaeocidaris spines:

 

 

This top surface was probably scraped clean by the Pleistocene glaciers. I'm not sure if it is the actual top of the formation.

[Wrangellian]

Nice fusulinids and spines, and is that some of the Archeolithophyllum there in the 2nd pic above?

[Missourian]

On 8/16/2012 at 2:20 AM, Wrangellian said:

Nice fusulinids and spines, and is that some of the Archeolithophyllum there in the 2nd pic above?

 

I believe it is phylloid algae, but I'm not sure if its red (Archaeolithophyllum) or green.

 

Here they are at full resolution:

 

[Wrangellian]

Right, I should have been more general - phylloid algae. Looks like lots of interesting things going on in that piece.

I assume you pried up a few of those spine/fusu chunks?

[Missourian]

On 8/16/2012 at 5:11 AM, Wrangellian said:

I assume you pried up a few of those spine/fusu chunks?

 

I took home some good chunks with fusulinids, but no spines.

[Missourian]

A silver lining of the current housing slump is the presence of some idled construction sites. While exploring Google Maps, I came across this one:

 

 

There appears to be an extensive area of exposed shale and many large blocks of limestone. Mosaic-like patterns of rock in the grass indicate joints in exposed beds of limestone or sandstone. Certain linear features could be outcrops or gullies. A large gully in the shale indicates that the bedrock has been exposed for at least a few years.

 

Based on the elevation, location, and its position atop a prominent ridgeline, I figured these are the Bonner Springs Shale and Plattsburg Formation.

 

Because the site is near some houses, I decided to park on the other side an expanse of thick grass. I didn't want to feel rushed, or worse yet, get chased off. That wouldn't be a problem today.

 

When I first reached the boulders, I could tell many of them are Spring Hill Limestone. The outcrop itself had been pretty well battered by heavy equipment, but I could make out areas of dark chert (on the right):

 

 

These little beds of chert, acting as a resistant cap to erosion, may be responsible for many of the larger hills in the area.

 

Below the outcrop is the mosaic-like pattern of joints in a bedding surface I mentioned above:

 

 

Some of the loose boulders have an intriguing fossil hash on the bedding surfaces:

 

 

I didn't find anything of note in this stuff, but the quality and diversity of the fossils warrants a second visit.

 

In previous posts, I've shown several broken or partially obscured myalinid shells. Here is a complete one:

 

 

This is probably Orthomyalina.

[Missourian]

A little ways down-section, we come to the Merriam Limestone, which is the thick-bedded, gray and maroon limestone at the bottom:

 

 

At the top of the underlying Bonner Springs is this bed of muddy sandstone (or is it sandy and muddy limestone?):

 

 

It contains small or fragmented shells of mollusks and a few brachs:

 

 

 

This is probably associated with the Derbyia zone I found a few days ago. At the bottom of the mostly-covered Bonner Springs is some poorly-exposed Farley Limestone (bottom):

 

 

This bed is essentially a mass of Osagia:

 

(I know I keep showing these, but again, they do serve as a really handy stratigraphic marker.)

 

Distinct crossbeds indicate that the Osagia grains formed shoals and drifts on the sea floor:

 

 

This block was likely flipped over.

 

Edit: The nature of the weathering on the right side may indicate that this block is stratigraphically upright. If so, then it displays hummocky cross-bedding, which likely resulted from the action of storm waves.

[Missourian]

The satellite image showed one good expanse of Bonner Springs, so I'll walk over there now:

 

 

As expected, the big gully had nicely cut through the shale:

 

 

At top of the shale is a rubbly, ferruginous rock with shell fragments. This stuff shows up on the satellite image. Stratigraphically, it is probably just below the impure sandstone.

 

The gray stuff is a mix of shale and sandstone. This piece of sandstone has some traces:

 

 

I'm not sure what the circular thing is.

 

In the gully, a clastic dike can be seen:

 

 

These form as loose pieces of shale fall into a fracture in the shale bedrock.

[Missourian]

When scouting out a site, it may be worthwhile to check any or all of the miscellaneous boulders scattered about. You never know what'll turn up:

 

 

Wow. The benthic critters really went to town there.

 

Abundant Osagia in the side gives it away as Farley. This also attaches an id to another Thalassinoides-covered boulder I examined several months ago ( http://www.thefossil...140#entry313924 ).

 

A nearby block has an aesthetic arrangement of Linoproductus and bryozoans:

 

 

Later in the day, I took another look at the area in Google Maps and spotted this rather large grouping of blocks and slabs:

 

 

That's a lot of bedding-plane real estate to examine....