MarcoSr Posted May 7, 2021 Author Share Posted May 7, 2021 A slab with oncolites from the Ordovician age, 495 Million yrs. old, from the Oneota Formation, Hwy Q, quarry north of Markesan Wisconsin (400g 8.5x3.75x.31 inches). Marco Sr. 1 "Any day that you can fossil hunt is a great day." My family fossil website Some Of My Shark, Ray, Fish And Other Micros My Extant Shark Jaw Collection Link to comment Share on other sites More sharing options...
Wrangellian Posted May 8, 2021 Share Posted May 8, 2021 (edited) Interesting. What are the little grains that make up the blobs, I wonder? The larger ones surrounding the blobs are oolites, if I'm not mistaken? Are they both examples of same? Edited May 8, 2021 by Wrangellian Link to comment Share on other sites More sharing options...
MarcoSr Posted May 8, 2021 Author Share Posted May 8, 2021 14 hours ago, Wrangellian said: Interesting. What are the little grains that make up the blobs, I wonder? The larger ones surrounding the blobs are oolites, if I'm not mistaken? Are they both examples of same? An oolite is a type of sedimentary rock composed of cemented ooids. I believe the piece is oolitic /pisolitic limestone with oncolites. The small spherical grains are ooids, the size of which determines whether the rock is oolite ( composed of cemented ooids with a diameter 0.25–2 millimeters) or pisolite (composed of cemented ooids with a diameter larger than 2 millimeters), which are the nucleus for some oncolites which are the much larger structures. Marco Sr. "Any day that you can fossil hunt is a great day." My family fossil website Some Of My Shark, Ray, Fish And Other Micros My Extant Shark Jaw Collection Link to comment Share on other sites More sharing options...
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