Backyard Trip

[Missourian]

Many moons ago, I spent many late afternoons exploring a park and nearby woods behind a local fitness center:

 

 

While my parents were working out, I was practicing my recon skills. I found a few outcrops along a creek, including this one with a nice little waterfall:

 

 

 

It hasn't changed a bit in 25 years.

 

The strata are the Raytown Limestone. More specifically, they appear to be the wavy beds in the middle of the unit.

 

This outcrop is where I found my first crinoid cup when I was 16:

 

 

This is Delocrinus. It is about 1 cm across. At first, the five-way radial symmetry made me think it was an echinoid. As luck would have it, I soon spotted an illustration of a similar Pennsylvanian crinoid in the guidebook 'Common Fossils of Missouri'.

[Missourian]

There is also a bit of Argentine Limestone peeking out higher up in the woods:

 

 

Unfortunately, the jungle has covered up most outcrops. I'll have to return in the winter to do a proper recon.

 

A bit of the jungle:

 

 

Bush honeysuckle is attractive, but it is an invasive species. The white blossoms have popped up in many places:

 

 

[Missourian]

In another park, I finally got around to checking a small creek near the trail. Large limestone fragments in the alluvium promised outcrops upstream. I made may way up through the weeds and undergrowth. After a short distance, I found some Chanute sandstone overtopped by limestone that had slid down from the Iola Formation above:

 

 

The Chanute up close:

 

 

The bedding of the sandstone is different at each outcrop. It seems to thicken overall as one moves southward.

 

There wasn't much more to see until I reached a road at the park boundary. I was sure I'd be covered with poison ivy and ticks, but I came out unscathed.

 

Star of Bethlehem is apparently nonnative, but it is not nearly as common as bush honeysuckle. This is the first time I've seen it:

 

 

Trail boss:

 

[Ludwigia]

Trail boss:

5958-trail-snake.jpg

Was he coming at you or heading in the other direction?

[Missourian]

On 5/19/2013 at 1:51 AM, Ludwigia said:

Was he coming at you or heading in the other direction?

 

Both, sort of. He was laid out flat while sunning when I approached. He briefly confronted me and then slithered away.

 

[nala]

Very nice! the snake is very impressive! i would run very fast!

[Missourian]

While walking near the Maple Woods Natural Area ( http://www.thefossilforum.com/index.php?/topic/25424-backyard-trip/?p=336363 ), I spotted some limestone exposed in a yard next to the sidewalk:

 

 

The oxidized rock has the 'cheesy' look of the upper Spring Hill Limestone:

 

 

Being near the top of the ridge line, the Spring Hill was expected. As it turns out, the escarpment of the formation can be discerned on topo maps:

 

 

The unit can be traced along the top of the steep-sided scarp (purple line). I marked all Spring Hill exposures that I've found with green X's. The Maple Woods spot is marked with an 'M'. There appears to be a second section of the scarp along the drainage to the south. I haven't found any exposures in that completely developed area.

 

These scarps highlight an interesting phenomenon in the area. With very few exceptions, rock outcrops in streams tend to be north-facing. This is almost certainly due to Pleistocene glacial activity. The lack of exposures on the north sides of valleys is probably due to deposition of till and loess and possibly glacial erosion.

 

Another thing I've noticed is that there are at least three varieties of clover, and that they all bloom at the same time:

 

 

 

Locust trees are also blossoming everywhere:

 

 

There are so many now. It's like a swarm of.... locusts.

 

"Whut?":

 

[Missourian]

I have no fossils or rocks to offer at this point, but I did find a miniature 'Pennsylvanian forest' on a construction site....

 

'Ferns' and 'Sigillaria':

 

 

'Calamites':

 

 

Unlike the others, these horsetails are related to their Pennsylvanian counterparts.

 

Definitely not Pennsylvanian:

 

[Wrangellian]

Good ones.. I keep thinking I'd like to put together a 'living fossil' garden, or at least distribute them among my mother's garden, but I don't really know where to get the good stuff for affordable prices or how much of it would survive in this climate), and the horsetails would become weeds, so....

[Ludwigia]

Definitely not Pennsylvanian:

6461-yellow-huddle.jpg

But nevertheless very pretty!

[Missourian]

On 5/26/2013 at 3:22 AM, Ludwigia said:

But nevertheless very pretty!

 

I haven't seen this type until very recently, and now it is one of my favorites. By the way, it is Hippocrepis comosa, a.k.a. horseshoe vetch, and is an Old World species. Here is another one with some white clover:

 

 

And just today, I found another variety of vetch:

 

 

Correction: The yellow-flowered plant is actually Lotus corniculatus, a.k.a. birdsfoot trefoil. The arrangement of the leaflets didn't look quite like those of horseshoe vetch shown in illustrations. L. corniculatus is also an Old World species.

[Ludwigia]

If they're old world, then there must be some hanging around here as well. Have to keep my eyes peeled. They're really beautiful!

[Missourian]

On 5/27/2013 at 7:40 AM, Ludwigia said:

If they're old world, then there must be some hanging around here as well. Have to keep my eyes peeled. They're really beautiful!

 

One source says it ranges across Europe, including Germany. Another says it prefers to grow in areas with limestone and chalk.

[Auspex]

...I also spotted these strange markings on a chunk in the creek bed:

5659-rock-markings.jpg

I have no idea what they are.

It appears to be very well weathered; I would not rule out their being the last remnants of shell hash impressions.

[Missourian]

Creatures with paws and tires left some 'trace fossils':

 

 

Those with shoes.... not so much.

 

I've yet to find a receptaculid. This 'one' will have to do for now:

 

 

Prairie blue-eyed grass:

 

 

For some reason, these little blue flowers are extraordinarily difficult to photograph with the iPhone.

[Roanoker]

For some reason, these are extraordinarily difficult to photograph with the iPhone.

So what? The results are exquisite. We don't mind if you go to a lot of trouble.

[Missourian]

On 5/29/2013 at 7:53 PM, Auspex said:

It appears to be very well weathered; I would not rule out their being the last remnants of shell hash impressions.

 

Since the Winterset is exposed along there, anything is possible. I wouldn't be surprised to find a kitchen sink in that unit.

 

On 5/30/2013 at 8:22 AM, Roanoker said:

So what? The results are exquisite. We don't mind if you go to a lot of trouble.

 

After a hundred attempts, I would hope so.

[Ludwigia]

Creatures with paws and tires left some 'trace fossils':

6686-bikes-&-dogs.jpg

Our new Australian member Pav would love that one

[Missourian]

I've spent a good part of the past two years exploring the 300-foot section of outcropping strata in my 'backyard'. So what lies below in the subsurface? I'm glad you asked. A good starting point would be to find descriptions of subsurface rocks as close to the area of interest as possible. I found such information in a publication on nearby Johnson County, Kansas at http://www.kgs.ku.edu/General/Geology/Johnson/04_subs.html . Better still would be to obtain some well logs. The Missouri Department of Natural Resources provides images of such logs here: http://www.dnr.mo.gov/env/wrc/logmain/ . I'd like to go really deep -- all the way to the Precambrian basement if possible. Although there are many wells in the 'backyard', there are none that are sufficient.

One well in Clay County, just to the north near Smithville Lake, extends down into the Ordovician. Three wells to the southeast, in Jackson County, penetrate the Precambrian basement:

 

The 'backyard' is the area outlined in green. The general direction of the dip and strike of the strata are shown in purple. The four drill sites are shown as numbered points linked together.

I took the four well logs and placed them side by side:

 

The numbered points representing the drill sites are shown at the top of each log. For all intents and purposes, the line linking them is a very rough cross-section of the terrain. The 'dip' in the middle reflects the Missouri River valley.

The depths below each drill site are shown in green at 500-foot intervals.

The logs can be a bit difficult to read or interpret, but I was able to identify a number of lithologic breaks in the sequence. I marked them in red and linked them together to show the trend of each horizon. Note that they dip to the left. This reflects the regional dip of the strata to the west northwest. They are, from top to bottom:

* Base of the Kansas City Group - This likely outcrops at the lowest elevations of the 'backyard', but I've yet to find it. I'll have to search along the Missouri River bluffs.

* Base of the Marmaton Group - The Kansas City and Marmaton Groups are separated by the thick shale and sandstone of the Pleasanton Group. The Marmaton can be differentiated by its distinctive fossils, including chaetetid sponges, the brachiopod Mesolobus, and the fusulinid Beedeina. The base of the group is about 500 feet below the surface.

* Base of the Pennsylvanian - Below the Marmaton is a thick sequence of shale, sandstone, and coal that comprises the Cherokee Group and possibly a couple formations of the underlying Atokan Stage. These beds are seemingly a homogenous mass in the logs. The base of the Pennsylvanian is about 1000 feet down.

* Base of the St. Peter Sandstone - The strata of the Mississippian, Devonian and upper Ordovicican are dominated by carbonates. They are difficult to differentiate in the logs. A major break in lithology is the ~100-foot-thick St. Peter Sandstone. Its base is about 1600 feet down.

* Base of the Ordovician - Below the St. Peter is a thick sequence of dolomite. The Gunter Sandstone, at the base of the Ordovician, makes for another handy marker. It is 2200 feet down.

* Top of the Precambrian - We continue down through various Cambrian dolomites until we reach the Lamotte Sandstone. Just below this is the 'Great Unconformity'. We are now down to 2800 feet, just over a half mile below the surface. The Precambrian basement rocks are igneous (primarily granitic), possibly with some volcanic and metamorphic rocks mixed in. The granitic rocks continue down for another thirty miles or so until the mantle is reached.

 

As you can see, the west-northwest dip of the beds are indicated on the log composite. Comparing the depth and thickness of the strata to the north and southeast, I averaged them together to estimate what lies directly below my feet. This chart is the result:

 

There is no yellow woodsorrel in the subsurface:

 

Nor is there chicory:

 

[Ludwigia]

Man, you really take your hobby seriously! Great underground field work and well presented!

[Missourian]

On 6/3/2013 at 5:27 PM, Ludwigia said:

Man, you really take your hobby seriously! Great underground field work and well presented!

 

Thank you. I'm a big proponent of spatial awareness.

[Missourian]

For comparison and reference, here is the official geologic map of Missouri:

 

 

By chance, the colors used for the Cambrian, Ordovician, Mississippian, and Pennsylvanian areas are fairly close to those used in my stratigraphic section. My 'backyard' is outlined in red on the west edge of the state.

[Ludwigia]

No Jurassic in the whole state? You poor guy!

[Missourian]

On 6/4/2013 at 1:53 AM, Ludwigia said:

No Jurassic in the whole state? You poor guy!

 

Southwest Kansas has a tiny bit, but it's nonmarine sandstone.

 

If I had one wish, I'd ask for Jurassic ammonites in the US like those in Europe. Those really are the best.

[Ludwigia]

If I had one wish, I'd ask for Jurassic ammonites in the US like those in Europe. Those really are the best.

I agree that they're great and abundant, but the ones from B.C. measure up to them very well. At least that area of America wasn't landlocked during the Jurassic.