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Showing results for tags 'hirnantian'.
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A nice Dictyonema flabelliforme dendroid graptolite from Oslo Fields in Norway. It's Tremadoc, Lower Ordovician in age and is thus maybe around 480 mya. Another angle :
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- amplexopora
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Today I decided to go and visit a roadcut that I red on one of the Silurian literatures I got my hands on (a big thank you to those that led me to those PDFs relating to the geology of the Niagara Escarpment). It turns out the roadcut on the Niagara Escarpment is near my home which is a pleasant suprise to me, considering that I have been disappointed by the Queenston formation. This roadcut is actually several exposures that run on an access road that can lead one to the upper part of Hamilton, Ontario. Here is the exposure I decided to explore. I chose this exposure as the access is a busy boulevard with cars driving by with no sidewalks and pedestrians. I had several people honk and call out to me as I was exploring the site. Maybe I should have worn a safety vest of some sort? Is that even necessary?
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- cabot head formation
- grimsby formation
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Hello dear fellow forum members, I just aquired a nice little hashplate (if I can call it that?) from Portugal. The information given is the following: Ralfina lusitanica and Helopora sp., upper Ordivician (hírnantian fauna) Queixoperra Member of Cabeço do Peão Formation, Amendoa-Maçao Portugal. What caught my eye is the rib-like structure on the right/ top right. I am not saying these are ribs, just describing the shape. Does anyone have any idea what this might be? Thanks and Aloha, J
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Late Ordovician mass extinction - volcanism and warming or cooling and glaciation?
Oxytropidoceras posted a topic in Fossil News
There is a series of open access papers about what caused the Late Ordovician mass extinction. They are: Bond, D.P. and Grasby, S.E., 2020. Late Ordovician mass extinction caused by volcanism, warming, and anoxia, not cooling and glaciation. Geology. https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G47377.1/586486/Late-Ordovician-mass-extinction-caused-by Mitchell, C. E., and Melchin, M.J., 2020. COMMENT: Late Ordovician mass extinction caused by volcanism, warming, and anoxia, not cooling and glaciation. Geology https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G47946C.1/587311/COMMENT-Late-Ordovician-mass-extinction-caused-by Bond, D.P. and Grasby, S.E., 2020. REPLY: Late Ordovician mass extinction caused by volcanism, warming, and anoxia, not cooling and glaciation. Geology. https://pubs.geoscienceworld.org/gsa/geology/article/doi/10.1130/G47984Y.1/587312/REPLY-Late-Ordovician-mass-extinction-caused-by Wang, G., Zhan, R. and Percival, I.G., 2019. The end-Ordovician mass extinction: A single-pulse event?. Earth-Science Reviews, 192, pp.15-33. https://www.sciencedirect.com/science/article/pii/S0012825218305099 https://www.researchgate.net/publication/331275476_The_end-Ordovician_mass_extinction_A_single-pulse_event https://www.researchgate.net/profile/Gx_Wang2 Yours, Paul H.-
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