Similarities And Differences Between European And North American Chalk

[Kosmoceras]

Hi all,

As many of you know, I mainly collect British chalk fossils. But the “chalk” has deposits in several different places. The Upper chalk which forms the White Cliffs of Dover in Kent is the same stuff which makes up Cap Blanc Nez in France. And the chalk continues through parts of Europe in Germany, Denmark, Sweden and some in Russia. There are more countries included but those are just a few.

I know a fair bit about that having visited most of those countries on my travels, but what I want to know more about is the chalk deposits in the USA. What is the Chalk Group lithostratigraphy?

This LINK shows a table with the Upper and Lower chalk of Europe lithostratigraphy and a bit of other information.

The fossils we find vary a fair bit, the bulk of the British chalk fossils to be found include sponges, echinoderms, brachiopods, bryozoans, bivalves, belemnites, ammonites, serpulids, disarticulated fish, and corals. We do not see any mosasaurs, and pristiophoriformes (saw sharks), echinorhiniformes (bramble sharks) and dalatiiformes (sleeper / kite fin sharks fins) have not been recorded from the British chalk.

What are the more common finds in the chalk on your side of the pond?

Many thanks,

[Missourian]

Here are the various Cretaceous rocks in Kansas:

From:

http://www.kgs.ku.ed...89/04_meso.html

The Kansas Niobrara Chalk contains vertebrates of all kinds, including many kinds of fish and mosasaurs, with a few rarities like Pteranodon, turtles, and birds. Invertebrates include inoceramids and the occasional rudist. I haven't heard of anyone finding ammonites, belemnites, or echinoids, but that doesn't mean they aren't there. And then there are the clusters of Uintacrinus.

The overlying Pierre Shale does contain ammonites.

I'm not sure about the strata in other areas. Of course, there are several forum members here who can fill in the details.

Edited February 1, 2013 by Missourian

[FossilDAWG]

The chalk units in Alabama (such as the Mooreville, Demopolis, and Prarie Bluff) look quite different from the European chalks. They are a sort of bluish-white, not white white, and have more clay content. They also tend to absorb water and swell up, then crumble to fine powder when the swollen chalk dries out. This tends to keep chalk gullies and glades from developing a soil cover, so they can persist and enlarge over time.

As far as fossils are concerned, one can find molluscs whose shells were/are calcitic, such as oysters (prominently Exogyra) and fragmented innoceramids. A large fauna of aragonitic bivalves, snails, and some cephalopods is indicated by phosphatized internal and sometimes external casts, but the original shell material is not preserved. If you look very closely, you can find barnacle plates and small brachiopods. Compared to the European chalk, belemnites are astonishingly rare. Exquisitly preserved shark teeth and bone can be found; vertebrates include a variety of bony fish, sharks, turtles, mosasaurs, rare plesiosaurs, and very rare birds and dinosaurs. Articulated specimens are rare, as carcasses lay exposed on the bottom for a long time and were dispersed by scavengers. The fauna seems quite similar to the Kansas chalk, even to the level of species.

Don

[Kosmoceras]

Thank you both for your input. It is interesting seeing the different layers and formations being at a similar time to the European chalk. Does anyone know the rough time span of North American chalk?

The fauna has both similarities and differences as we can see. Small brachiopods and barnacles are found, and as for ammonites again a similar pattern. They are barely preserved in chalk, only being preserved as composites or internal moulds. After death the shell fills with sediment which has partially consolidated; the shell then disappeared entirely or is replaced by a layer of pyrites, which commonly oxidised to limestone, and so the external skeletons are poorly preserved as moulds. This also makes them difficult to prepare.

Belemnites are found only in certain areas, more in the Upper Chalk I find - good exposure at West Runton, Norfolk.

Come to preparation, chalk fossils from the UK are reasonably easy to prepare, also being pours. I assume your chalk is also easy to prepare?

I wish some of the vertebrate material you find where you are was also present in the European chalk, the odd ichthyosaur tooth or any reptile material is extremely rare. Once a dinosaur was found in the English chalk, but that is the only one on record.

Regards,

[jpc]

well, I don't know much about NAm chalk, but that photo looks like the ferry loading spot in Dover...

[Kosmoceras]

well, I don't know much about NAm chalk, but that photo looks like the ferry loading spot in Dover...

You are spot on, that is the Port of Dover. A few more pictures on a brighter day.

[erose]

Here in the US the Cretaceous chalks are all part of the Western Interior Seaway or the Gulf (of Mexico) Embayment. Those are shallow continental deposits. Along the east and west coasts of North America the deposits are different. Despite that many of the same fossils are found in both environments. Maybe we see more echinoids and corals out here in Texas than back in New Jersey but otherwise the same critters were present. In Texas the Austin Chalk Group (Upper Cretaceous) is probably the largest stratigraphic unit of typical white chalk.

Edited February 1, 2013 by erose

[Foram-Mike]

Dear Kosmoceras,

I collect foraminifera - a microfossil very common in chalk. I have built a collection of about 1000 Cretaceous foram-images from both sides of the Atlantic (all online !). The issue to correlate the material faszinates me and my colleagues, but we lack so far enough US-samples.

Our status at the moment is

- I packed the few US-samples into a stratigraphical chart at http://www.foraminif...upcretgulf.html Clicking on the orange fields brings you to the foram-images.

- we are building an Atlas of European Maastrichtian foraminifera: http://www.foraminif.../atlasboma.html

- I started to build a list of Cretaceous index-foraminifera: http://www.foraminifera.eu/ifcue.html

I would say we have a firm basis on Maastrichtian and Campanian material from Europe and would thus be capable to correlate US samples with European material.

Probably our approach is too specific for you, but I just wanted to let you know. Maybe there is a way to cooperate on this subject of correlating Europe with America.

Edited February 2, 2013 by Foram-Mike

[KansasFossilHunter]

Here are the various Cretaceous rocks in Kansas:

From:

http://www.kgs.ku.ed...89/04_meso.html

The Kansas Niobrara Chalk contains vertebrates of all kinds, including many kinds of fish and mosasaurs, with a few rarities like Pteranodon, turtles, and birds. Invertebrates include inoceramids and the occasional rudist. I haven't heard of anyone finding ammonites, belemnites, or echinoids, but that doesn't mean they aren't there. And then there are the clusters of Uintacrinus.

The overlying Pierre Shale does contain ammonites.

I'm not sure about the strata in other areas. Of course, there are several forum members here who can fill in the details.

There are definatly ammonites and rarely belminites in the smoky hill chalk.

[KansasFossilHunter]

And at least in Colorado the Pierre shale contains ammonites

http://www.itano.net/fossils/pierre/pierre.htm

[Kosmoceras]

Thanks for the information. I have indeed heard and read up a fair bit on chalk foraminifera, but sadly I don’t have the equipment to look at them. Thanks for the links to pictures too, very interesting.

This is an example of the ammonites without shell:

Regards,

[Missourian]

There are definatly ammonites and rarely belminites in the smoky hill chalk.

It's funny how our group found fish of all kinds, mosasaurs and even a Pteranodon wing, but no ammonites.

[KansasFossilHunter]

It's funny how our group found fish of all kinds, mosasaurs and even a Pteranodon wing, but no ammonites.

What hunt?

[Missourian]

What hunt?

I've been only twice and found various fish parts. The other guys had gone out several times since the 1970's. I didn't see the Pteranodon, but I did see the excellent Platycarpus skull.

[KansasFossilHunter]

I've been only twice and found various fish parts. The other guys had gone out several times since the 1970's. I didn't see the Pteranodon, but I did see the excellent Platycarpus skull.

Other guys? On the forum? I have a chalk ammonite... My pteranodon?

[Missourian]

Other guys? On the forum? I have a chalk ammonite... My pteranodon?

I don't think any of them are on the forum.

[Ramo]

I've heard of ammonite impressions, and internal molds of ammonites from out in the chalk, but I think they are extreemly rare. There have been a few aptychi found preserved out west. Here in central Kansas, we have some beautiful ammonites in the Blue Hill Shale, and quite a few impressions here in the Greenhorn Limestone. I'd venture to say they are fairly common in the Greenhorn, as I have a few in the Limestone sidewalks around my house.

Ramo

[Ramo]

Sorry, Kosmoceras, I seem to have drifted from your original question. Here is a picture of a typical days finds for me and my wife. We also walk over thousands of pieces of clam shells that we only pick up to verify that they are, in fact, clam shell fragments. We can usually expect to find a couple small shark teeth, a few fish teeth, and a hand full of fish verts. It also isn't uncommon to pick up a fish tail, and a small string or two (4-5 inches) of fish verts.

Ramo

[Foram-Mike]

Thanks for the information. I have indeed heard and read up a fair bit on chalk foraminifera, but sadly I don’t have the equipment to look at them. Thanks for the links to pictures too, very interesting.

the equipment needed is a binocular with 40x magnification for $50-80.