Richard, my grandmother from Great Falls had a pudding stone The clasts were rounded, just under an inch in diameter, and of red and green colors I associate with belt rocks. It was rounded itself. Could it have been from a local formation?
I'm challenged to think of a lithified conglomerate made of Belt-rock clasts, but that does not mean it can't exist. The common conglomerates from Montana would be more like black and white (see the Kootenai at the end of this post https://richardigibson.substack.com/p/cantwell-formation ) because they are made mostly from the Phosphoria chert, which is mostly black to yellow-brown. A red and green clast conglomerate sure sounds like the Belt, as you know, but when it would have been deposited and lithified, I don't know, but probably long after Belt time. Possibly a Belt-sourced rock deposited in the Cretaceous somewhere near the mountain front? Sorry I don't have better ideas for it.
The Planetgeo podcast did a program on puddingstone back in March of last year, including the Lorraine Quartzite. Available on Spodify or from the PlanetGeo webpage. see PlanetGeo: The Geology Podcast
Geology of Puddingstone
Mar 13, 2025 Season 5 Episode 8
In this exciting episode of Planet Geo, Chris and Jesse dive deep into the fascinating world of pudding stones! From the picturesque Hertfordshire pudding stones in England to the Roxbury conglomerate in Massachusetts, and finally the scientifically wondrous Lorraine Quartzite pudding stone abundant in Michigan. They discuss the unique geological stories each of these beautiful rocks tells and explore their origins, formations, and scientific significance. Plus, get ready for some rock-solid fun facts about the ancient landscapes and climates these stones reveal. Don't miss this riveting geological adventure that promises to be a conglomerate of knowledge and excitement. Let's rock and roll!
Richard, my grandmother from Great Falls had a pudding stone The clasts were rounded, just under an inch in diameter, and of red and green colors I associate with belt rocks. It was rounded itself. Could it have been from a local formation?
I'm challenged to think of a lithified conglomerate made of Belt-rock clasts, but that does not mean it can't exist. The common conglomerates from Montana would be more like black and white (see the Kootenai at the end of this post https://richardigibson.substack.com/p/cantwell-formation ) because they are made mostly from the Phosphoria chert, which is mostly black to yellow-brown. A red and green clast conglomerate sure sounds like the Belt, as you know, but when it would have been deposited and lithified, I don't know, but probably long after Belt time. Possibly a Belt-sourced rock deposited in the Cretaceous somewhere near the mountain front? Sorry I don't have better ideas for it.
Thanks, Richard: now I’m really curious about that stone -and my memory of it. I may have kept it. I’ll look around.
Thanks for your columns. They bring me more joy than just about anything in my email.
Thanks!!!
The Planetgeo podcast did a program on puddingstone back in March of last year, including the Lorraine Quartzite. Available on Spodify or from the PlanetGeo webpage. see PlanetGeo: The Geology Podcast
Geology of Puddingstone
Mar 13, 2025 Season 5 Episode 8
In this exciting episode of Planet Geo, Chris and Jesse dive deep into the fascinating world of pudding stones! From the picturesque Hertfordshire pudding stones in England to the Roxbury conglomerate in Massachusetts, and finally the scientifically wondrous Lorraine Quartzite pudding stone abundant in Michigan. They discuss the unique geological stories each of these beautiful rocks tells and explore their origins, formations, and scientific significance. Plus, get ready for some rock-solid fun facts about the ancient landscapes and climates these stones reveal. Don't miss this riveting geological adventure that promises to be a conglomerate of knowledge and excitement. Let's rock and roll!
Thanks for sharing that, I didn't know about it.
Enjoyed this!