Lower Ordovician Fossils in Undocumented Silicate Stone Formation

[Philip Rutter 2]

Hopefully, there are some folks here who may remember me.  I joined rather briefly around 5 years ago, with multiple photos of mostly macro fossils from the lower Ordovician - that I could not get identified.  By way of re-introduction, I'm an ABD PhD- from long ago; essentially a broadly trained evolutionary ecologist; some actual education in geology and paleontology.  

 

Then Covid hit; and hit me and mine quite hard; just recovering now.  The fossils are still very much here; and very much unidentified.  Not for lack of trying!  I've been talking and showing them to 2 former Heads of Geology Departments, and a few more professional geologists.  Plenty of interest- very friendly folk- but- at this point they are all assuring me that they are NOT paleontologists; but geologists.  And, alas, my 2 Dept. Heads are now saying all their old paleontologist colleagues- are "gone"; one way or the other, mostly to do with age.  And they don't know where to send me.

 

It's not like the world is full of paleontologists who can honestly claim expertise in the Ordovician- and I do need experts.  For a long list of weird circumstances.

 

To start with- the fossils are located near the top of the "Oneota Dolomite" formation, which is of course dolostone, not dolomite, In the SE corner of Fillmore County, Minnesota.  That formation is pretty consistent dolostore, about 300 feet thick, and for me, theoretically overlain with the New Richmond Sandstone, which barely gets into Minnesota.   The juncture is an unconformity, of a large but unknown number of years, but the New Richmond is still considered "lower Ordovician."

 

So, dolostone below, sandstone above, yes?  But my fossils are - ~95% pure silicon dioxide, in a layer that is 95% silicon dioxide, that is mostly snow white, does not fracture like chert, with the silicon layer some 15'-30' thick- and- nobody has ever really mapped this formation; or much noticed it.  

 

Finally did find one professional notice - from hundreds of miles away in Wisconsin.  In 1956, this geologist described the exact twin of my formation; stones, thickness, and fossils- identical.   JOURNAL OF SEDIMENTARY PETROLOGY, Vor.. 23, No. 3, Pp. 174-179 FIGS. 1-4, SEPTEMBER,1953
SILICIFICATION IN THE ONEOTA DOLOMITE, N. PROIOPOVICH University of Minnesota.  That's a bear to dig out- I have a PDF, but it's supposed to be a behind the paywall thing.

 

Lots of surveying indicates this layer of white silicate is not a scarce formation; rather it is seldom exposed, and the kind of stone that quarries and engineers hate- it's much harder than your tools, and will destroy your grinders- so - just get rid of it and get back to work.  Nobody has noticed it.

 

The formation is abundantly supplied with fossils- just run off the common list of Ordovician stuff- most I have identified.  But there are also plenty that don't seem to be identified anywhere, including some major ones.  My favorite is Big Bertha; a solid block of silicate (probably 6 tons)- that nobody so far can identify at all.  Kinda looks looks like a big modern reef coral- but it has none of the coral signatures.  If it's a stony sponge- it's not like any others.  Complex innards, complex rock- that my 10 lb quarry breaker bounces off of.

 

Here's the big juicy bait- my site is ~ 20 miles away from the Decorah Impact Event, cause of the Winneshiek Lagerstätte fossil site.  Did my strata get rumpled when that thing hit?  Sure.  When?  I've taken to ignoring the next "official" statements about "middle, or lower" or 470M or 440M... none of the authorities have checked with each other.  That metorite hit very close in distance; and time- and my fossls sometimes come out of the overburden - as a single, isolated fossil; no surrounding stone.  Um.  Oh, and all the fossils are totally undeformed- except by predators; lots of them are obviously from bottom sediment.  Extremely fine detail is totally preserved- I suspect soft tissue also, as in some chert.

 

At this point I've been working on this formation for some 7 years, with a good deal of effort.   I've got thousands of photos at this point, finally did get a good camera and lens.    Thing is- the photos are all hopeless to convey the actualities- as most of you already know.  I need experts to come and see, hands on.

 

This is supposed to be an "introduction", right?  lol.  So I'll stop- with a few photos.  Sorry, scale not always well provided, but can be inferred, and I do better now.

 

Looking for forward to comments and questions!

Edited September 1 by Philip Rutter 2
spellign

[Fin Lover]

Welcome back to the forum!  

[Philip Rutter 2]

Many thanks!  :-)

[Jaybot]

Welcome back!

[Philip Rutter 2]

Many thanks  :-)

 

[Fossildude19]

Welcome back! 

I've merged your old and new accounts.

 

BTW,  Picture 4 looks like an Orthocone Cephalopod.

[Philip Rutter 2]

Bless you for finding my, um, fossil comments and merging!  I couldn't figure out how to connect to the old account.  Thanks!  Also thanks for the new vocabulary!  I was just going with nautiloid -   that is one, they're abundant in my rocks.  I've got one which took me 3 years to figure out; it includes a centimeter plus exposed length of off-center siphuncle - with very detailed structure.  It's spiral.   I've got a fair photo- but it would be incomprehensible to the uninitiated -    let me know if interested.   Thanks again!

[minnbuckeye]

13 hours ago, Philip Rutter 2 said:

  Kinda looks looks like a big modern reef coral- but it has none of the coral signatures.  If it's a stony sponge- it's not like any others.  

 my site is ~ 20 miles away from the Decorah Impact Event.  Did my strata get rumpled when that thing hit?  That metorite hit very close in distance; and time- and my fossils sometimes come out of the overburden - as a single, isolated fossil; no surrounding stone.  Oh, and all the fossils are totally undeformed

 

Just a few thoughts from a non geologist and non paleontologist. Fillmore County is to me the Karst Capital of the world. With no structure to the specimens illustrated in your post, did you consider the possibility of mother nature creating the structures? I know personally how hard some of the rock formations in the area can be yet they contain ample evidence of acid water working on the rock. And if the Decorah Impact deformed the strata as you question, why do the fossils not show similar alterations. Just being loose suggests erosive evidence more than impact alterations.

 

By the way, welcome back and hope to see more of your finds in the future. Your unknowns are probably similar to mine!

 

Mike

 

 

[Philip Rutter 2]

Hi, Mike- those are all really good questions!  I enlisted the top MN karst geologist, who has seen all the photos and even done a little X-ray fluorescense analysis.  I took that same turn- I ASSUMED they were non-biological, for the first 3 years of looking at them.  But I'm also very familiar with reef organisms, I was walking on live coral reef when I was in the 1st grade, Guam-   some of these look more like corals than others, but- gradually it grew on me.  I also did a lot of caving in limestone caves in college; lead groups, southern Indiana and Ky.  These few photos cannot show the weight of evidence; I am really very careful in making any determination, always based on many separate points.  

 

A good example - after some years, I got my mother-in-law, visiting from Colorado,  to look at Big Bertha, in situ; photo #3 above is a small shoulder of Bertha I managed to break out using quarrying techniques - this is the inside, as it fractured out; somewhat cleaned up.  The rust stains do obscure the white, or cream here silicate.   She's a PhD Geologist - most of career spent working on satellite photos; but - trained.  The outside of Bertha does not look like the inside; she'd seen this stone earlier, but- first looks.   I was telling her at this point that Bertha, which I managed to crack a 1,000 lb slab off the top off- is actually all one organism..  and she would NOT let me have that!   "Oh, this could be pure geological for me; let me look! "  After 20 minutes of examination, hands on, intense, hand lens now and then... she said, "Ok. It's biological.  See here...?" and pointed out about 5 details- all going to - this huge thing was made by life.  Took her that long- and I was delighted with her demand on independent examination.  That's the right way.

 

I've started trying to expose a complete face of the formation- that's how I ran into Bertha - she's about 4' above the Oneota dolostone layer, with pure white silicate above and below- and blocking my dig.  Looked at her a year before deciding to just break this boulder up and get it out of the way - after a week managed to split the top off; crack that shoulder out- and both showed clearly- this thing is a fossil; so I quit breaking it.

 

Absolutely, yes, the loose fossils, like photos !, 2, and 5 (all) are a big fat puzzle.  In #5, the big one I have my hands on, came out of the bottom watercourse, a usually dry run; but ancient, and when in flood a genuine ball-mill of stones rolling.  That's why it's rounded.   #2, which I think is a stony sponge of some sort, I plucked out of the valley wall forest soil, as is.  The ridges sticking out are crystalline quartz and extremely fragile - this never saw serious erosion.  I've TA'd several courses  in Invertebrate Zoology - and this isn't anything that makes sense to me.   At 20 miles from impact, I would guess the theoretical shallow estuary would have had a good tsunami, of both water and mud- making it possible for a reef or estuary at the time to be either immediately buried - or raised out of the water and killed.  Then - standard sedimentary processess could be considerably bent.  Experience is very slender there.  

 

Really need to get the face of the formation completely exposed - it's already been surprising.   There are about 10 PhD theses, and 30 MS theses- just waiting to be done here.  Hint hint.  The fact of a pure silicate layer - IN the unconformity between dolostone and sandstone - should be tempting I think.

 

2 more photos here; first one is a chunk next to that shoulder of Bertha; as freshly broken out.  The gray stuff in the columns is the PUREST clay I have ever encountered in my life- I pinched out a ribbon over 8 inches long-  second photo is the 1,000 lb top slab my mother in law examined; facing us is the bottom of the slab, that's a hoe handle to the left for scale- I found a crack in Bertha i was able to get steel wedges into - there was a 2 mm layer of clay between stones, evidently a break in the growth of the critter.  With the forces involved, I expected this stuff to break/shatter into much smaller bits - but - its astonishingly strong; stronger than any coral- which of course would be carbonate, and this is silicate (I think!)  Haven't gotten this x-rayed yet; but- hardness is in the silicate range; most of my white stuff is MOS 7.2.

 

A huge problem with interpreting these stones/fossils/formations is their age- They have millions of years to shuffle atoms around - the dolostone under is usually guessed at 450 Mya - I've had trouble finding hard dates;  Kentucky limestone caves are around 100 million years younger - I think it might be a mistake to assume a lot of similarities- 

 

You're not very far away...   :-)    I'll take a look at your stuff on line here today - wife hollering for something right now... 

 

 

Edited September 2 by Philip Rutter 2
multiple fixes

[Philip Rutter 2]

Um, Mike - can you direct me to photos of your 'unknowns' - or other stuff?  I haven't got the navigation on this site figured out yet.  I can find your "posts"  but - surely, somewhere here, there's a "gallery" of yours?  

[Mark Kmiecik]

Welcome from Illinois.

[Gizmo]

Welcome back aboard! 

[Philip Rutter 2]

Greetings all.  I hope to be making a series of posts on FFM, regarding the geological anomaly I've been working on for some 7 years now.  This post is intended to lay down for all to see the basics of the formation - this is more important than usual, because so many aspects of this stone are - very literally - unique.  Except for one publication, from 1953 (well buried and unknown) I haven't found another formation like it in the literature.

 

Location: the formation is in SE Fillmore County, Minnesota, USA, arguably in Pierce County, Wisconsin, and by fossil identification possibly in Winona County, Minnesota.

 

The surrounding area is known as "The Driftless Region" to many here, named because the "glacial drift", gravels etc associated with the Pleistocene glaciations ubiquitous in most of Minnesota and  Wisconsin - are not found here.  The Driftless extends into Wisconsin, Illinois, and Iowa.  The glaciologists long ago discovered that for reasons still not understood, the continental glaciers split and went around us; leaving hilly terrain not flattened by glaciers, but formed by ancient rainfall / stream erosion.  Whereas farmers just 50 miles west of us are plowing clay loams likely to be full of glacial erratic boulders and gravel, the farms around here are plowing silt loams without stone of any kind, derived from aeolian deposits of loess.  Where my first well was drilled, the loess is over 6 meters (20 feet) deep; not uncommon.  The soil depth is highly variable at this point, erosion of tilled loess is horrifying; and some ancient wind drifting phenomena likely play a part.

 

A you travel towards the Mississippi from the middle of Fillmore county, the land becomes less and less farmable, because the hills get steeper, deeper, and closer.  In that country is where my silicate formation is, the nature of the land is why it hasn't been noticed before.

 

I've had long conversations, including with the expert geologists, on why these blinding white stones have not been "noticed".  Multiple reasons.  A) both moss and lichens grow on them instantly- if exposed in the natural world they quickly are not white; either on land or in water.  B ) the stone is very hard; but- also rigid and will shatter with a good whack.  Having watched 3 1,000 year floods cut my dry run 1 meter deeper in 5 hours - then fill it again- these streams are highly efficient ball mills; with boulders of all kinds as the balls.  The stone in the water course bottoms is fascinating; because it includes glacial stone from events far older than the Pleistocene- basalt to gabbro- plenty hard.  This silicate, once in the stream- will be pounded into sand very rapidly.  C)  It isn't everywhere the 2 other formations meet- surveys of where the Oneota meets the New Richmond do not mention any muilti- meter silicate in between.  And D), a surmise based on my surveys and broken wrist - where the silicate is exposed by stream erosion, it tends to from a ledge that prevents erosion above it, and allows erosion beneath- leading to a very steep valley.  True for me- which is how I broke my wrist rolling down a 75° hillside for 35 meters or so.  That's where the outcrop was- and it's too snarge steep for anyone sensible to be wandering around on.

 

There is - alas and hurray; a LOT more to this story, but I'm already long here.  The photo below is typical of the material I sent to the U of M; you can see the very straight fractures, and some of the "figure" in the stone that looks like possible fossil origins.  Pretty sure this is mostly sediment from those shallow seas, including plant and animal parts - consolidated as Geology loves to do, in ways not explained to us.  Sorry for the hand- but one thing that is a real problem for me is that stark white is very hard to photograph so any detail comes through.  Gotta take what I can get.

 

Those of you wanting to tell me I'm a complete idiot, please do.  I'm used to it.  :-)  And, I'm not.

 

After a 1,000 year flooding rain (we've had 2 more since...) I noticed a glaringly white something halfway up a hill- where no such thing should be.  I discovered to my astonishment that it was a stone- about 30 cm cubic, but not regularly cubic.  This was after living on this land for 40 years, tilling, building a house with stone collected from the dry-run drainages - even learning to quarry the common Oneota dolostone.  I knew a fair amount about stone and geology (first wife was an ABD PhD Geologist...) and this white stone was just totally not like the dolostone or sandstone that every farmer here recognizes.  Not.   Heavy- and hard as the dickens; my first guess was I'd tripped on an oddball pocket of dolomitic marble - something known to happen elsewhere.

 

I sent two fist-sized samples to the University of Minnesota expert on this exact region; he ran his X-ray fluourescence test on it- and announced I had  - chert - 95% pure SiO2.  It isn't chert, with which I am well familiar - that nice conchoidal fracture- is entirely missing in the white stone, replaced by repeating fracture and form that is distinctly rhombohedral.   MOS hardness - 7.2.  Sure isn't anything from the carbonates world.

 

But - known geology below; Oneota dolostone; and above; New Richmond sandstone - are both reasonably well studied and characterized, and a pure silicate layer, which after 3 years and one broken wrist of surveying I estimate as varying from 3 m to 8 m thick - is just not mentioned anywhere.

 

My 7 year educated guess is that the silicate is IN the unconformity known to lie between the Oneota and the New Richmond.  Ain't that interesting?

 

The photo is a sample like the ones sent to U of M - note the very straight fractures - 

 

More to follow!

 

 

Sorry for the Hand - this stuff is very hard to photograph, being blinding white - getting detail visible means taking what I can get as I learn.

Edited September 5 by Philip Rutter 2
missing text

[Randyw]

25 minutes ago, Philip Rutter 2 said:

I sent two fist-sized samples to the University of Minnesota expert on this exact region; he ran his X-ray fluourescence test on it- and announced I had  - chert - 95% pure SiO2.  It isn't chert, with which I am well familiar

So you’ve had an expert test it and come back with a proven result but you don’t believe it because it doesn’t look right? Not disputing one way or the other just making sure I read that right…

im not seeing any fossil in this picture by the way….

and I’m also not seeing anything inconsistant with chert fractures….

chert is also a hardness of 7. On the M.O.H.S scale

Edited September 5 by Randyw

[Philip Rutter 2]

41 minutes ago, Randyw said:

So you’ve had an expert test it and come back with a proven result but you don’t believe it because it doesn’t look right? Not disputing one way or the other just making sure I read that right…

 

 

 

 

Yep, you're reading that right.  :-)   Rejecting expert opinion is a very, very long conversation- but I would bet you would grant as a starting point that SOMETIMES - it can be necessry.   My own default is that expert opinion really should be believed as first intent- but- scientific skepticism includes questioning experts.  Incidentally; I can claim to be knowledgeable regarding chert.  I have successfully contributed to the Wikipedia page - on Chert, and not regarding this kind of stone, but chert per se.  They forgot something; I pointed it out- and in 3 days my correction was permanently incorportated- by a whole panel of experts.     

[Randyw]

Please do not put different word into my quote. It makes it appear that I said it wich I didnt is rude and against forum rules!

@Fossildude19 can we get that changed please?

[Philip Rutter 2]

I'm truly sorry, but I'm not following you- the quote is exactly that, using the quote methods here- what words do you object to?  I do not intend to misquote, or to be objectionable.  

[Fossildude19]

Just now, Philip Rutter 2 said:

I'm truly sorry, but I'm not following you- the quote is exactly that, using the quote methods here- what words do you object to?  I do not intend to misquote, or to be objectionable.  

 

 

 

Your reply was in a quote box, attributed to RandyW.

 

I fixed that in the interim.

 

Kind of like this:

 

1 minute ago, Philip Rutter 2 said:

This is text that Fossildude19 wrote, that looks like it was something that Philip Rutter 2 said. 

This can cause misunderstandings, if you are not careful about where you are posting. 

 

 

@Randyw - Not sure there is a setting for that, but I will look.

 

I believe it was just an error on Philip's part. I've fixed it for you. 

[DPS Ammonite]

Welcome to the Forum Philip.

 

Looks like chert to me, especially likely if it is not scratched by a metal knife. Chert has all kinds of surface textures. Not all has nice conchoidal fracturing.

 

See this article with references that mentions the wide variety of chert in the Oneola Dolomite.

 

https://legacy.igws.indiana.edu/IGNIS/GeoNamesDetails.cfm?ID=1C9421DA-9D51-4ECD-AB27-8699733E9F6D

 

Geolex is another website for finding info about rock layers:

https://ngmdb.usgs.gov/Geolex/UnitRefs/OneotaRefs_3108.html

Edited September 5 by DPS Ammonite

[Randyw]

@Fossildude19 thank you. I’m sure there’s probably not a setting for that. I was just wanting the changed quote fixed.

@Philip Rutter 2 Thats o.k. Accidents happened but as these posts will be able to be seen for decades I hate to see misquotes… if you do an online search you will see dozens of chert pieces that look just like yours.  
im still saying chert with no fossils visible…

it looks right. The hardness is right, and the tests and expert says it’s right…. I dont see any reason to question those results…

Edited September 5 by Randyw

[Philip Rutter 2]

Fossildude19 - thank you very much!  I am, in fact, having some difficulty navigating this site, it's new to me, and for some reason not intuitive.   In the present case, I could not find, with a 45 second search, any other box besides the quote box , that would let me enter text.  It's not impossible that my browser is out of date- it IS out of date, I'm using a Chrome version so old that Google no longer supplies updates for it; unless I buy a new computer.   In multiple cases I've looked for buttons- boxes- and not found them, sometimes at all.  Working on it.

 

As for "Is it chert" - any actual chert expert will laugh at anyone who insists this is chert- that is flint or isn't ... etc.  The entire field is full of vehement and contradicting opinions - with PhDs.  The expert who said "chert" to me- laughed- agreeably - at my disagreement.  And noted - he's seen 2 samples, and I've handled - multiple hundreds.   We're happy with it.   

 

As for no fossils visible - quoting myself: "This post is intended to lay down for all to see the basics of the formation "  - doesn't mention fossils in this post- just the geology of the formation; which - if you do a little search- you will find is documented nowhwere- except in the Wisconsin paper from 1953- which no geologist I have questioned had ever heard of.   Fossils later for this thread.

[Philip Rutter 2]

DPS Ammonite - many thanks all around- the article link is greatly appreciated; that one had never surfaced for me.  Their description of chert in the Oneota agrees with my own; there is an abundance of oolitic chert, as well as other oolites.  They refer to bands of chert some meters thick- that's new to my info, and I wanna see them.  :-)

 

This quote from that paper: "The Oneota conformably overlies the Potosi Dolomite and conformably underlies the Shakopee Dolomite except in northwesternmost Indiana " - is sadly typical of my experience in trying to dig out info here.  All my references assure me that here the Oneota unconromably overlays the Jordan sandstone- my well records show that in fact - and is overlain unconformably here by the New Richmond sandstone, and north a bit unconformably by the St Peter sandstone - and further north something else.

 

This paper is nearly the only work on the New Richmond in this area; good work, too: https://www.carleton.edu/departments/geol/Resources/comps/CompsPDFfiles/2005/Robins2005.pdf

She examined several near by exposures- and found no silicate layers between New Richmond and Oneota - 

 

Puzzles remain.  :-)

[DPS Ammonite]

4 hours ago, Philip Rutter 2 said:

As for "Is it chert" - any actual chert expert will laugh at anyone who insists this is chert- that is flint or isn't ... etc.  The entire field is full of vehement and contradicting opinions - with PhDs.  The expert who said "chert" to me- laughed- agreeably - at my disagreement.  And noted - he's seen 2 samples, and I've handled - multiple hundreds.   We're happy with it.   

Having a geology degree, I noticed that geologists include lots of cryptocrystalline and microcrystalline varieties of quartz in the term chert. That includes jasper, flint, opal, agate and chalcedony. I try to give a more specific name such as opal, chalcedony etc if the rock is distinctive, but realise that others may call it just chert. 
 

Look at Mindat for a definition chert with references:

 

https://www.mindat.org/min-994.html

[FranzBernhard]

"Silica rock" formed in freshwater, that means, formed in lakes?

Franz Bernhard

[Al Dente]

12 hours ago, Philip Rutter 2 said:

I sent two fist-sized samples to the University of Minnesota expert on this exact region; he ran his X-ray fluourescence test on it- and announced I had  - chert - 95% pure SiO2.  It isn't chert, with which I am well familiar - that nice conchoidal fracture- is entirely missing in the white stone, replaced by repeating fracture and form that is distinctly rhombohedral.   MOS hardness - 7.2.  Sure isn't anything from the carbonates world.

 

Not all chert behaves the same. Some cherts have very nice conchoidal fracture while others not so much. Native Americans would heat treat some types of chert to improve knapping ability (improve conchoidal fracture) while other types of chert didn't require heat treatment. Most midwestern chert is formed from silica replacing limestone. There are varying amounts of replacement. If your sample is 95% silica, then it could be the 5% that is preventing nice conchoidal fracture.