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Post by hummingbirdstones on Jul 10, 2022 21:53:05 GMT -5
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Post by jasoninsd on Jul 10, 2022 22:20:32 GMT -5
Robin, thank you SO much for posting the link to this. I was just thinking about this kind of map the other day...and didn't know where I could locate one! Thank you, thank you! I already downloaded the pdf for South Dakota!  |
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Post by amygdule on Jul 10, 2022 22:51:22 GMT -5
jasoninsd , You don't remember this thread from 2020 Man oh man - thank you for all those links you provided here! I'll mess around with the Geologic Database for sure! I clicked on the Pierre Shale google link. It led me to a Didymoceras Nebracense. What I took as an ammonite imprint in one of my rocks, and in fact some what I took as ammonite pieces (pics 3-7 in this post: forum.rocktumblinghobby.com/post/1138309/thread) could very well be Didymoceras Nebracense rather than ammonite. Here's a link I found for the Didymoceras Nebracense (click on images to bring up photos): www.cretaceousatlas.org/species/didymoceras-nebrascense/
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Post by jasoninsd on Jul 11, 2022 0:25:10 GMT -5
jasoninsd , You don't remember this thread from 2020 Man oh man - thank you for all those links you provided here! I'll mess around with the Geologic Database for sure! I clicked on the Pierre Shale google link. It led me to a Didymoceras Nebracense. What I took as an ammonite imprint in one of my rocks, and in fact some what I took as ammonite pieces (pics 3-7 in this post: forum.rocktumblinghobby.com/post/1138309/thread) could very well be Didymoceras Nebracense rather than ammonite. Here's a link I found for the Didymoceras Nebracense (click on images to bring up photos): www.cretaceousatlas.org/species/didymoceras-nebrascense/ I thought it looked familiar! LOL Apparently not! LOL |
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jamesp
Cave Dweller 
Member since October 2012
Posts: 36,618
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Post by jamesp on Jul 11, 2022 6:42:16 GMT -5
Nice USGS link hummingbirdstones. Oddly my computer would not open it until I used your link here. So I went straight to the Tuscaloosa Formation in Alabama and it revealed in that description that the pet wood I'm finding is local and not transported from some great distance. Alabama state geology maps only said 'wood beds', not 'local wood beds'. It makes a difference. For instance if this wood was transported from the north it would likely suggest a colder species. It is good to know when fossil hunting in the Tuscaloosa Formation that findings should be local land organisms and likely not just the same marine fossils usually found at the coastal plains.  |
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,618
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Post by jamesp on Jul 11, 2022 8:10:37 GMT -5
I sort of figured out how to use this link. This example is simple because it is mostly thin oceanic deposits. The pet wood I find is close to the coastal plain line/GR(Goat Rock fault) and it's intersection at north end of line E to E" at the lower right of map.  The underground cross section of line E to E". Note long thin oceanic deposition layers in greens and brown until they hit granites at right. The granite zone was the ancient beach where the wood piled up(Tuscaloosa Formation).  Close up of north end of line E to E" where Tuscaloosa deposition layer(Kt) hits granites and Goat Rock fault. This is the ancient beach when ocean was 350 feet deeper. This is where the wave action pushed the trees up for petrification. The layer higher and above this was volcanic ash rich clay that covered up the trees for petrification.  And for the heck of it the south end of line E to E" to the ocean is massive layers of sand with bikini clad ladies sunbathing above(not shown). Note how flat the various perfectly intact layers have been deposited with little debris or transitional disruptions between the layers suggesting very rapid deposition.  |
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