Backyard Trip

[Malcolmt]

Very nice reporting and pretty darn good pictures. We have a village like that (Upper Canada Village) less the fossils up here in Ontario that was a number of buildings that were transported from various locations when they flooded for the power dam on the St Lawrence near Cornwall. As a youth I used to collect in some of the quarries and debrie piles from the dam construction. To bad my mother disposed of all my finds after I moved out. To her they were just rocks taking up space in the garage. As I recall I had a few really nice cephalopods in the two to three foot range.

[Missourian]

On 5/8/2012 at 6:43 PM, Malcolmt said:

To bad my mother disposed of all my finds after I moved out. To her they were just rocks taking up space in the garage. As I recall I had a few really nice cephalopods in the two to three foot range.

 

She threw them all away? Oy....

 

At least that didn't include your latest find.

[cgoings]

Hello all:

I thought you might be interested in some chert exposure maps I am creating for Iowa. I am doing it one county at a time and have Henry and Washington counties done. I am working on Louisa County right now. It takes awhile to publish each map because I am ground-truthing as I go. You can go to www.rollinghillsconsulting.com and click on County Chert Maps to access them. If you follow RHCS on Facebook, you will be notified when the next map is up and sometimes I post fossil pictures too.

These maps would also be useful for fossil hunters in Iowa because it shows where chert-bearing formations are outcropping. Hope this is helpful!

Chad

[Missourian]

I got a fever, and the only prescription is more strata....

 

A few months ago, I made my way up the big creek. I encountered a couple exposures of Argentine Limestone:

 

 

There was a decent talus pile in place, but I didn't find any decent fossils:

 

 

A little further up, I found a second cut:

 

 

The slightly dipping beds indicate the presence of a small, gentle syncline in the vicinity.

 

I checked out some slabs at the base, but nothing turned up fossil-wise:

 

[Missourian]

More recently, I returned to an old favorite, which a few miles further from home. This road cut contains a long sweep of Argentine. It has treated me well on occasion.

 

A zone in the upper part of the Argentine contains many productid brachiopods. Most conspicuous are Juresania, Echinaria, and Antiquatonia. The sheer number of fossils, in part, causes the limestone to crumble into chunks that litter the base of the outcrop:

 

 

Fossils, such as this Echinaria, protrude from the rock face:

 

 

Fortunately, all one has to do is pick through the rubble to find some goodies:

 

 

The brachs often break out clean, more or less:

 

 

In the past, I've found some exceptional fossils at this locale. I was rewarded with this Peripristis tooth after a modest amount of effort:

 

 

Here is another Peripristis alongside an Ameura cephalon:

 

 

Most remarkable of all is this Dictyonema graptolite:

 

[Missourian]

Below the Argentine is about thirty feet or so of the Liberty Memorial Shale:

 

 

The shale is mostly covered here, but a few fossils can still be found. Most can be found in the bottom portion. Aesiocrinus and the pelecypod Phestia are the most conspicuous.

 

Some stems (right) and Aesiocrinus anal sack fragments:

 

 

In the past, I'd found some more complete sacks:

 

 

These seem to be more common here than at other Liberty Memorial spots.

 

The clam Phestia:

 

 

Lophophyllidium, our most common horn coral:

 

[Fossildude19]

Missourian,

I truly enjoy reading your geological/stratigrapical exploits.

Thanks for posting them here.

Regards,

[Missourian]

Thanks Fossildude. I'm enjoying your Excellent Adventure as well.

[Missourian]

There is a sharp boundary between the Liberty Memorial and the underlying Raytown Limestone. This surface contains a profusion of fossils. Most conspicuous are poorly-preserved productid brachiopods, but little surprises like this Ameura tail pop up from time to time:

 

 

All three members of the Iola formation are well exposed at a nearby exit ramp:

 

 

The alga Archaeolithophyllum is particularly prominent in the Raytown at this site. I call it 'salad stone':

 

 

Calcite has filled the voids beneath the blades.

 

The platy Muncie Creek Shale can be seen separating the Raytown from the Paola Limestone:

 

 

I picked a few phosphate concretions from this bed:

 

 

As always, most are duds. I did find a couple that are marginally interesting:

 

 

The underlying Chanute Formation is almost entirely covered. The only bit showing was this small exposure of sandstone:

 

 

Up close, it's kind of interesting:

 

 

The vague little BB-sized things are likely filled burrows, but I can't tell for sure. In any case, bioturbation seems to have stirred up the original bedding structure.

[Missourian]

Below the Chanute, we come to the Cement City Limestone:

 

 

This is one of the better outcrops I've been able to find.

 

Most interesting to me is an intraformational conglomerate in the upper part:

 

 

 

It is made up of pebbles mixed with various fossils including crinoid fragments and brachiopods. It is likely related to the nodular bed we've seen earlier. The pebbles were derived from underlying layers within the Cement City. Chunks of sediment were eroded in a high-energy environment, perhaps in the surf, and were then deposited here.

 

Above this is a bed made of fossil debris:

 

 

This may be a continuation of the bioclastic 'cap rock' seen at other spots. Also, note the Neospirifer above my thumb. It is strange to see such a delicate shell within a rough-and-tumble conglomerate.

 

Below the conglomerate are several inches of shale mixed with lenses of limestone. Further down is about three feet of mostly medium-bedded, micritic limestone:

 

 

This is the level to look for the stratigraphically diagnostic Caninia coral:

 

 

This one was hit by a drill during highway construction.

 

Near the base of the outcrop, the blue-olive beds are just accessible:

 

 

Fusulinids are present here, which is a first for me with these beds.

 

To find the beds near the base, I had to scramble through some brush:

 

[Missourian]

And a strat chart for the road cut:

 

[Missourian]

While scouting road cuts along a highway a few miles to the north, I spotted an outcrop of Spring Hill Limestone with a flat, bare top:

 

 

Since I'd found silicified sponges at a similar exposure not too far from here ( http://www.thefossil..._20#entry282418 ), I thought it would be worth stopping to take a closer look.

 

At the other spot, the sponges were actually imbedded in the top of the Captain Creek Limestone, which is separated from the Spring Hill by the thin Vilas shale.

 

Instead of sponges, I found various types of pelecypods:

 

 

This means I was dealing with the shallow-water facies of the upper Spring Hill rather than the deep-sea Captain Creek-Eudora Shale contact.

 

After a thorough search of the platform, I found a few more pelecypods, a few battered brachiopods, and this:

 

 

This is likely some kind of fish spine, and was a pleasant surprise and nice change of pace. After several months of backyard exploring, I finally found a truly cool fossil. Or at least since I found the Heliospongia in the link above.

 

Lastly, there are signs of glaciation on the flat surface. Pebbles of quartzite and granite were present, and faint striations can be seen extending in a north-south direction on the flat surface:

 

[papercut]

Excellent report and amazing pics. You must be a geologist~~is that right~

I shall take this post to study……some geological english~

And expecting your next trip!

[Missourian]

On 6/11/2012 at 11:49 AM, papercut said:

Excellent report and amazing pics. You must be a geologist~~is that right~

I shall take this post to study……some geological english~

And expecting your next trip!

 

Thanks.

 

I guess you can call me a recreational geologist.

 

I'm looking forward to my next trip too.

[Missourian]

Saturday afternoon, I checked out some more Spring Hill Limestone not too far from the outcrop shown at http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__st__180#entry325318 . This unit hasn't produce anything too spectacular, but it does throw out a few surprises from time to time.

 

Only the upper half is present here:

 

 

A massive, 5-foot bed dominates the exposure. Mollusks are abundant in the top:

 

 

These include a variety of small gastropods and pelecypods.

 

Apparently, the top of the bed is an ancient surface. Strange mineral growths were scattered about:

 

 

The Pleistocene glaciers left their mark as well:

 

[Missourian]

Below the massive bed, the thinner layers produced some decent brachiopods. These Juresania retain many of their spines:

 

 

A bryozoan has hitched a ride on this Juresania:

 

 

Actually, the brach was likely dead at the time.

 

And then there are these faint, ring-like things:

 

 

Some image enhancement brings them out a little:

 

 

Actually, these are cross-sections of 'tubes'. It's possible they could be a type of sponge, but more likely, they are some form of burrowing. Under the microscope, they appeared to be made up of sparry calcite, with a couple tiny fossils thrown in.

[Missourian]

Another day. Another outcrop....

 

Since it wasn't too brutally hot today, I ran up to another road cut not too far from the one I visited over the weekend ( http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__st__200#entry332956 ). I just noticed it a couple weeks ago. I think I've known about it for years, but never stopped.... Anyway, it features the top of the Spring Hill Limestone, along with the Captain Creek Limestone and a couple poorly-exposed shale units:

 

 

As with the previous stop, the outcrop is dominated by a massive bed of limestone that caps the Spring Hill. This reminds me of the thick, root-bearing bed in the lower Winterset ( http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__st__40#entry284693 ). There even seems to be roots in the top-most portion here, but these very well could be burrows:

 

 

Below these, there are a number of actual burrows:

 

 

Above the massive bed is a covered gap (Vilas Shale) followed by some fossiliferous limestone. This is the Captain Creek:

 

 

In the rock face, phylloid algae and Composita brachiopods are common. The heavily weathered surface may predate the road excavation.

 

The top of the unit bears a few fossils. They include fusulinids:

 

 

and the occasional myalinid:

 

 

At another site described in an earlier post ( http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__st__200#entry330548 ), the presence of pelecypods led me to think I was dealing with the top of the Spring Hill rather than that of the Captain Creek. I'd like to return to and reassess the other exposure at some point.

 

Above the Captain Creek is some shaly-looking material:

 

 

This could be Eudora Shale, but as glacial till is often present in the area, I had to 'scratch the surface' to be sure:

 

 

Yep. That is in situ fissile shale. Also included are several small, white concretions. I didn't see any trace of black shale. A tannish zone a few feet above probably includes till, as there were a few glacial erratics scattered about.

 

As a bit of (more) recap ( http://www.thefossilforum.com/index.php/topic/25424-backyard-trip/page__st__20#entry282417 ), the same beds are fully exposed about a mile to the northwest:

 

 

The 'massive bed' is marked in red. Being at the top of a 20-foot cliff, those beds are too difficult to reach.

[Missourian]

It's been too darn hot to collect, and I don't have access to a decent camera at the moment, so I enjoyed the A/C as I drew up the Spring Hill Limestone from the last few stops:

 

 

And for fun, here's an image composite showing a 'complete' section:

 

[Auspex]

Your composite of the series is pretty cool: great idea!

[astron]

Missourian,

Your excellent reports with the surrounding geo infos and your fine pics and finds have justifiedly established this thread as one of the hot points of TFF...

Keep your good work on...

KInd regards.

Astrinos

[Kehbe]

Missourian,

Your excellent reports with the surrounding geo infos and your fine pics and finds have justifiedly established this thread as one of the hot points of TFF...

Keep your good work on...

KInd regards.

Astrinos

Ditto in every respect! Thanks Missourian!

Edited July 7, 2012 by Kehbe

[Missourian]

Thanks everyone.

 

Regarding the composite, my ultimate goal is to assemble an image composite of the entire 300-foot section. It may take a while....

[Missourian]

The Maple Woods Natural Area is a nice stretch of hilly forest tucked away in the suburbs. It is renowned for its virgin stand of maple and oak. This was my first visit.

 

Along the road leading to the preserve is this exposure of Argentine Limestone:

 

 

The tight, thin bedding is characteristic of the unit.

 

At the entrance is this bridge that leads to some trails. For now, I'm more interested in the creek bed:

 

 

A good thing about the current drought is that good-sized streams like this are currently dry, allowing for easy walking.

 

Not too far upstream, I came to a fork in the creek. I started off with the smaller tributary. Along the way, I soon encountered some shale:

 

 

Not too much further, I scrambled over some massive limestone:

 

 

followed by some sandstone:

 

 

I figured these beds were part of the Farley Limestone. They seemed to be at the right level, but I didn't see any fossils or other features that would pin down an id.

[Missourian]

I returned to the main creek and continued upstream. As I rounded the bend, I found another exposure of the layers we have just seen:

 

 

Below the lip of the waterfall is about three feet of shale. This likely is the Island Creek:

 

 

The massive limestone, for some reason, tends to fracture in the upper half:

 

 

This allowed the creek to carve a shallow trough into the top of the limestone.

 

The middle Farley is made up of sandstone and shale:

 

 

Abundant trace fossils indicate that this was marine sand:

 

 

Ripple marks were also present.

 

The Farley is substantially thinner here than at other exposures I've seen. The unit, with its variable thickness, lithology and bedding, is always interesting. Another nice thing is that it can be identified by abundant Osagia in the thin limestone bed at the top:

 

 

After following the creek until I could go no further (i.e. I would have to get my feet wet), I returned to the bridge and then hiked the trail loops. Near the top of the hill, I encountered this limestone that appeared to be really old excavation for an abandoned road bed:

 

 

Judging by its level above the Farley, it most likely is Spring Hill Limestone. The thick, somewhat irregular bedding has the appearance of the middle of the Spring Hill I've seen at nearby exposures.

[Missourian]

FWIW, a strat chart for my latest excursion: