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Showing results for tags 'decorah'.
Found 16 results
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A nice Dictyonema flabelliforme dendroid graptolite from Oslo Fields in Norway. It's Tremadoc, Lower Ordovician in age and is thus maybe around 480 mya. Another angle :
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From the album: Minnesota Ordovician Decorah Cephalopods
A large Endoceras proteiforme. From Decorah shale. Only a little section of the shell remains on the lower half. The segmented part are septum and the smooth part are siphuncle. -
Seem to be two different group (I'm talking about the larger shells not Sowerbyella minnesotensis) but I'm not sure. Top rows appear to have wave like ripples described as Bellimurina charlottae. From Southeast Minnesota in solid beds of limestones associated with Decorah Formation. I wish I have one showing inside of shell hinges.
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Does anyone know of deposits other than the LeGrand crinoids where each species is preserved in a different characteristic color, all on the same slab? We have this kind of thing in the brachiopods and trilobites of the Decorah Formation (Late Ordovician) here in Missouri, which is what got me thinking about it. But I've never seen a report summarizing other cases of this phenomenon, and as I think about it I'm not sure I can name any others. Can you? Brachiopod photo info: A= Zygospira B= Rafinesquina C= Doleroides 1 = Isotelus, rusty brown 2 = ?Achatella, light gray. Highway M near Antonia, Jefferson County Decorah Formation, Late Ordovician, ~450 million years old
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Several gastropods from Galena Formation near Decorah Iowa
tombk posted a topic in Fossil Hunting Trips
I was recently near Decorah, which is in northern Iowa and near the border with Minnesota. The predominant bedrock there is the Galena Formation. It is chiefly limestone with some interbedded shale. I was there only one full day and had other things to do (other than look for fossils, that is, if you can believe it). I did visit one road-cut along highway 52. I am not geologically informed enough to know what member of the formation was exposed at the road cut, so the closest I can get to dating it is to say that it’s upper Ordovician. The road cut was not a place I’ll visit again. Few fossils. But I did come across a few gastropods that I want to show here. And I have one question in the middle about clockwise vs counterclockwise growth in gastropods. I think 3 are Liospira species: Another looks similar but spirals from the umbilicus outward in a clockwise direction out from the rock (that is, toward the viewer looking at the rock) rather than into the rock as the others do. Any thoughts on this reversal of direction? Can it occur in the same genera or species? A possible Sublulites species: And an internal cast of a Hormotoma species (the first cast of such I’ve found where the whorls don’t touch each other). thanks for reading my mini-adventure, Tom
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Last month I was able to make a brief trip to hunt the Ordovician rocks of the Upper Mississippi Valley. The stratigraphy up here was very confusing to me at first since a lot of the units are very similar looking. To that end, I am endeavoring to include more site pictures in my trip reports of this area, in the hope that it will assist others when collecting this area. My first stop was in SE Wisconsin. Unfortunately the right of way was much narrower in person than on Google Earth so I did not feel comfortable collecting here. But it was a great site to observe the three lowest members of the Platteville Formation. The lower massive dolomite is the Pecatonica Member, the middle thinner bedded limestone layer is the Mifflin Member, and the slightly thicker bedded limestone above is the Grand Detour Member. These can be tough to differentiate on unweathered outcrops, but become quite distinctive after weathering. Next I checked out a couple of my favorite Maquoketa Formation stops in NE Iowa and had some luck, although I have nothing to show as everything is off being prepped. I also stopped at a very long roadcut exposing the top of the Decorah Formation and the entire Galena Formation. This picture shows the contact of the Ion Member of the Decorah and the overlying Dunleith Member of the Galena. The Ion is well known for having an abundance of the gumdrop bryozoan Prasopora. The one on the right below is itself encrusted with other bryozoans. This was the end of the first day. On the second day, I made my way up to SE Minnesota for the first time. The picture below shows the contact between the Prosser (Dunleith equivalent) and Stewartville (Wise Lake equivalent) Members of the Galena Formation. The Stewartville is well known for the lovely large gastropod molds that can be found, such as this very displayable Maclurites. I finished off the trip at two sites in the Maquoketa. Graptolites were probably the most commonly encountered fossil, although they weather quickly and you need to split rock to find nice fresh examples. And to finish off the report, here is the best of the trilobites I found. The cephalon has some damage, but it is otherwise a nice inflated specimen. Anataphrus vigilans Elgin Member, Maquoketa Formation Fillmore Co., MN Prepped by Malcolm T. Thanks for looking, hope you enjoyed!
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I found this in Decorah Iowa at a road cut. I don’t know whether it is from the Decorah Formation, though. I used a thin, stiff wire to scrape away some of the matrix. I wonder whether it is the lower part of a trilobite. Thanks for any thoughts!
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From the album: Trilobites of Minnesota Decorah/Platteville/Galena Formation
Ceraurid hypostome. Platteville Formation (SW corner specimen) and rest are Decorah Formation. For a long time I thought it was little rolled up trilobites, that's how much the hypostome look like. Tiny .5 cm for Decorah ones and .6 cm for platteville ones. Decorah ones seem to be uncommon to common and very easily overlooked because of its tiny size. Heck I wonder how many had I overlooked over 5 years. -
We've been finding these oddball puffy stars in the Late Ordovician (Sandbian) of eastern Missouri (Illinois Basin), in the uppermost part of the Plattin Group (a Platteville equivalent) or possibly the lowermost part of the Decorah Group (Katian). We've been finding a lot of weird fossils in that zone, including articulated cyclocystoids, but these I'm at a loss on. They seem to be calcite and preserve in the same texture and color as other echinoderm material in the same rock. They vary in convexity and in the presence of a central hump or divot, but there never seems to be a lumen that goes all the way through as far as I can tell. Some possibilities: stelleroid crinoid (but where anatomically? cystoid (but where anatomically? Up for other ideas or insights. Seen anything like this before?
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A friend uncovered this oddball today in the Late Ordovician (Sandbian) of eastern Missouri, in the uppermost part of the Plattin Group (a Platteville equivalent) or possibly the lowermost part of the Decorah Group. He's been finding a lot of weird fossils in that zone, including articulated cyclocystoids, but this one I'm at a loss on. Too wobbly for an orthoconic cephalopod, too much space between calcite elements for a crinoid column. Given the size, is machaeridian a possibility? What other ideas should we be considering?
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I found this chunk of shale poking around a bluff side a while back near Lilydale Park in Minneapolis, MN. The fragment pictured is translucent and is slightly concave, it reminds me of a cheek plate but Im not sure. I'm new at this so I'm pretty clueless, I appreciate any help.
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Hello, bug lovers! I found some pretty cool trilobites this last Sunday at my favorite road cut in Wisconsin. Since I'm a bit of a noob with bugs I'd appreicate some help on IDs and a confirmation on the formation. I think this is the Platteville formation. But it could be Decorah.....? @piranha Sorry for the pics in advance. Lol Found as is. After a bit of prep. Gabriceraurus mifflinensis? Ceraurinella scofieldi (possibly more thorax)? Continued..........
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While I was looking at a recent post here on the forum trying to help someone identify a Lepidodendron tree root I realized I had found something similar to Lepidodendron bark that I had just assumed was a piece of coral since I found it near other aquatic fossils. I found is somewhere near Decorah, Iowa (I don't remember exactly where). It's a bit worn, but does anyone know what it is?
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I have a few hash slabs I use for educational purposes, and I'd done a couple of events recently, so I was taking a look at one of the slabs and noticed this small fossil. It is approximately 6.5 long by 3 mm across. The shape is roughly triangular, and the cross section may be triangular (it could be a V-shaped "sheath"); unless it is incomplete or collapsed, it cannot be four-sided. It is not perfectly symmetric, but slightly curved and lopsided (although the skew of the keel could be a preservational artifact). Both exposed surfaces have linear markings, so that it looks vaguely segmented, but on closer inspection the lines seem to mark the edges of long narrow "scales" which appear to be slightly imbricated. The hash slab was collected last spring from a spoil pile left by house construction on the Mississippi River Boulevard, St. Paul side, a few blocks south of Summit Avenue. I know it is Decorah Shale, but I can't provide more detailed stratigraphy. I assume it is from the lower third of the formation, based on geography. (The scale bar in the photo is mm-scale.) The object doesn't look like any of the usual suspects (coral, bryozoan, brachiopod, bivalve, nautiloid, snail, trilobite, echinoderm, trace fossil). It shares some aspects with conulariids, but the texturing does not look like discrete rods, and it doesn't appear that the cross-section could be four-sided. The only other thing that came to mind is a hyolith, but do hyoliths have this kind of texturing when well-preserved?
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Are there still any good sites for the Decorah Shale in the St. Paul area? Shadow Falls has exposures, but they are not productive (only small bryozoan fragments, small brachiopods, and the occasional small trilobite fragment). We used to find large burrow casts and recepticulites at Lilydale Park, but it is closed permanently. Are there any other sites that yield the same kinds of things?
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Eastern Missouri / Southwestern Illinois Fossil Localities
Osteodontokeratic posted a topic in Member Introductions
Hello Fellow Fossil Officienados, I just recently retired and was wondering if anyone in the Greater St. Louis area would be interested in going on some fossil collecting expeditions? Been collecting in the area for 4 years and know there are a lot more places to go to find some quality &/or unique specimens than where I have been. On occasion, to the safer road cuts, I started taking my oldest grand child, age 8. He is getting the bug! So in addition to any more remote locales that I am willing to go to, would also like to know if anyone knows of a place that is relatively safe for an 8 year old. Have taken him so far to a Decorah site on Highway M & a Fern Glen site off I-55, in Jefferson Co., Missouri. BTW, I am a member of EMSP, ESCONI, and formerly of SIESC. Am also interested in going further afield. Recently visited the I-64 road cut near Sulphur, IN. Take care, ODK
