Talk:Colorado Group

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U.S. coverage?
I have made many edits to articles covering the Colorado/Kansas members of the Colorado Group, but I until this week I had not critically examined it. My observation, in short, is that the article, as originally posted, covers the Canadian classification and rather omitt the prior use in the United States.

The 1856, Meek and Hayden described their “Upper Missouri” series; Dakota, Benton, Niobrara, Pierre, and Fox Hills.

In 1876, Hayden grouped the three marine units (Benton, Niobrara, and Pierre) under the name Colorado, but this group was soon revised to just the lower two. As the Benton was replaced with Graneros, Greenhorn, and Carlile, these units took the Benton's place in the Colorado Group.

However, the classification is problematic. By the 1960, Donald E. Hattin, who litterally wrote the books on the members of the Colorado Group in Kansas suggested that the Colorado Group classification had no pracical use.

On one hand, the terrestrial Dakota (et.al.), and the marine Graneros, Greenhorn, and Carlile, and Niobrara each have different facies and distinct topographical expressions; but on the other hand, they are all found together in their outcrop and their collective topographical sequence (examples, the Smoky Hills, Dakota Hogback, the upper plains Arkansas/Cimarron Valley). In this presenation, they are often accompanied by the Ogallala, while the marine Pierre is often off somewhere else with the more terrestrial Fox Hills doing its own subdued thing.

So, the first impression is that the Colorado Group, at least in Kansas and Montana, is falling out of use.

Is the same happening with the Canadian usgage?

The real question I have is how to handle the article's present Canada-centric coverage of the Colorado Group, paricularly when I really don't know where the Colorado name is being retained, even whether it is actually a particularly important, current name presently in Canada.
 * Should this article really be extended to cover U.S. usage?
 * Is the sequence stratigraphy or chronostratigraphy of the Canada classification more or less consistent with the Colorado/Kansas usage?
 * Is the Canadian usage more relevant?
 * Should Canadian usage take the lead in this article, effectively as the main topic?

IveGoneAway (talk) 22:46, 25 April 2021 (UTC)


 * Update: Historically, Canadian usage was extended from Montana usage, which was extended from Wyoming usage adopted from Colorado/Kansas. Presently, however, Geolex provides records sugestive of Montana's abandonment of the name. Wyoming State Geologic Survey presently makes no mention of the Colorado name in its stratigraphic charts or current descriptive bulletins. USGS does not list the Colorado name as in use in Wyoming. KGS's current stratigraphic charts include the group, but current publications generally mention the classification only to state that it is not useful. The USGS lists Colorado Group as used in Colorado (where the unit has some topographical and economic significance (ditto New Mexico and Utah? IDK, the quarries and mills have closed in the last decade)). IveGoneAway (talk) 13:13, 29 April 2021 (UTC)


 * Hmmmm.... that said, since Gilbert (1895), the Colorado Group has been the recurring focus for validation of Milankovitch cycles theory.
 * So, a History of exploration should be added to explain the above and Lythology should be expanded to reflect the exploration and its relevance to Milankovitch cycles. IveGoneAway (talk) 01:59, 10 May 2021 (UTC)


 * Added History of exploration. IveGoneAway (talk) 00:00, 23 May 2021 (UTC)

Correlation reading
I wanted to capture these potential citations while I have them up (from Favel Formation):


 * Collom, C.J. 2000. High-resolution stratigraphy, regional correlation, and report of molluscan faunas: Colorado Group (Cenomanian – Coniacian) interval, Late Cretaceous, east-central Saskatchewan. In: Summary of Investigations 2000, Vol. 1, Saskatchewan Geological Survey, Sask. Energy Mines, Miscellaneous Report 2000-4.1, p. 82-97


 * Christopher, J., Yurkowski, M., Nicolas, M. and Bamburak, J. 2006. The Cenomanian–Santonian Colorado formations of eastern southern Saskatchewan and southwestern Manitoba. In: C.F. Gilboy and S.G. Whittaker (eds.), Saskatchewan and Northern Plains Oil and Gas Symposium 2006, Saskatchewan Geological Society, Special Publication 19, p. 299-318.

From this, usage seems to be current, in at least Canadian publications on the Williston (the Williston seems a particular point of historic insertion of Colorado/Kansas usage into Canada):





IveGoneAway (talk) 13:31, 20 June 2021 (UTC) 13:53, 20 June 2021 (UTC)