Bob Saunders Posted March 13, 2020 Share Posted March 13, 2020 2 inch by 1/2 inch with Crinoids, Bryozoans, more and did not expect to see the 3/8th inch 0.9 cm pyrite on it. Allegan County, Michigan From my dig site Yesterday. I believe it is limestone. Would like the approximate age for the fossils and about when did the pyrite form on it? Link to comment Share on other sites More sharing options...
connorp Posted March 13, 2020 Share Posted March 13, 2020 Was this found on its own or within a larger rock unit? The bedrock in the area is Mississippian, but these looks more like the Devonian fossils to me. I've seen shale/limestone from what is likely the Silica Shale and Dundee Limestone used as landscaping rocks and fill in quite a few locations in the lower peninsula, so that is a possibly. Link to comment Share on other sites More sharing options...
digit Posted March 13, 2020 Share Posted March 13, 2020 I'm not sure if this map which shows the bedrock geology would indicate the formations exposed at the surface. If it does, then Allegan County would seem to be covered with Coldwater Shale (Mississippian) along the coast and the southwestern part of the county and Marshall Formation (Carboniferous) toward the northeast. https://www.michigan.gov/documents/deq/1987_Bedrock_Geology_Map_301466_7.pdf Not sure if this helps much but it is a start. Cheers. -Ken Link to comment Share on other sites More sharing options...
Bob Saunders Posted March 13, 2020 Author Share Posted March 13, 2020 Thanks, this is about 5 miles inland of Lake Michigan. Where the coveted? Septarian Nodules aka lightning stones are found. A man from church used his crane with what I call a drag link to take his farm pond down to around twelve feet deep last summer. He told me I can come and look all I want. He now plans do dig more for me this summer. I have posted some of my other finds on here. This one is from yesterday near the top of #3. Using a small child's rake. quote "Oh help!" end quote. as weather permits I will be using my screens again. lot's of clay and a Petoskey stone. Link to comment Share on other sites More sharing options...
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