hitekmastr Posted August 4, 2012 Share Posted August 4, 2012 (edited) I found this at St. Clair in a pile of small rocks and boulders on top of a hill at the fossil fern site at St. Clair PA - obviously these are not Pennsylvanian swamp fossils - I believe this was part of a load of older rocks and boulders dumped there from when this was an active mining pit. The rock is hard sandstone or silicate - burrow/fossil was replaced by quartz). The tunnel or fossil starts on one side and makes a U-shape to the other side. One side looks like it is filled and the other side looks hollow. I've found other specimens showing the same pattern, as well. Update (26 Oct)! - Since posting this, several Forum experts have formed a consensus that this is a quartz vein rather than a burrow - I'm personally still a bit skeptical, but respect the experts on the forum who have seen many more fossils than me. Here is an illustration on page 215 in Donald Hoskins' excellent book (Fossil Collecting in Pennsylvania) - which looks like this - showing a burrowing "marine worm" (annelid) that is found in hardened sandstone and is thought to have inhabited both marine and freshwater sand. It is always U-SHAPED - the creature lived in the burrow and obtained food that circulated through the U shaped burrow. This fossil looks like it wraps around the rock. I added several photos (number A, B and C below) to show the end of the rock (the bottom of the "U"). A, B and C walk you around the rock. HOWEVER - Forum advisors suggest that the "burrow" is actually a vein of quartz running completely through the rock. This is exactly why the Forum exists, to clarify misconceptions by new fossil hunters (and veterans, too!) - so the input from Forum regulars is MUCH appreciated. Whether this is a quartz vein or Arenicolites, here is a 2005 research paper entitled: TREPTICHNUS AND ARENICOLITES FROM THE STEVEN C. MINKIN PALEOZOIC FOOTPRINT SITE (LANGSETTIAN, ALABAMA, USA) by ANDREW K. RINDSBERG and DAVID C. KOPASKA-MERKEL - this is available free online. Edited October 26, 2012 by hitekmastr Link to comment Share on other sites More sharing options...
Malcolmt Posted August 4, 2012 Share Posted August 4, 2012 Hard to see in these pictures need one with more resolution Link to comment Share on other sites More sharing options...
Auspex Posted August 4, 2012 Share Posted August 4, 2012 Crinoid stem, me thinks. "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Scylla Posted August 4, 2012 Share Posted August 4, 2012 I have found rock fractures infilled with quartz crystals at St. Claire Link to comment Share on other sites More sharing options...
hitekmastr Posted August 5, 2012 Author Share Posted August 5, 2012 I have found rock fractures infilled with quartz crystals at St. Claire This weekend I saw the same pattern in a sheet of shale but it didn't survive fragmenting - so apparently this is something that reoccurs...maybe a burrow of some sort... Link to comment Share on other sites More sharing options...
the tatter Posted August 5, 2012 Share Posted August 5, 2012 I'm with Auspex on this, eroded crinoid stem Discovery consists of seeing what everybody has seen, and thinking what nobody has thought. Albert Szent-Gyorgyi Link to comment Share on other sites More sharing options...
Scylla Posted August 5, 2012 Share Posted August 5, 2012 I have to say, never even seen a crinoid segment out of St. Claire, let alone a whole stem. Great find. Lots of crinoid bits down the road at deer lake too. Link to comment Share on other sites More sharing options...
Auspex Posted August 5, 2012 Share Posted August 5, 2012 The matrix doesn't look to me to be native to the shale layers...am I wrong about that? "There has been an alarming increase in the number of things I know nothing about." - Ashleigh Ellwood Brilliant “Try to learn something about everything and everything about something.” - Thomas Henry Huxley >Paleontology is an evolving science. >May your wonders never cease! Link to comment Share on other sites More sharing options...
Shamalama Posted August 6, 2012 Share Posted August 6, 2012 All the rock in St. Clair is Pennsylvanian in age and terrestrial in nature. You won't find marine fossils in the shales or sandstones because it was a flood plain/estuary. What you found is a quartz infilling of a crack in sandstone. I can't explain why it looks like vertical lines but I've found enough my self to recognize it. -Dave __________________________________________________ Geologists on the whole are inconsistent drivers. When a roadcut presents itself, they tend to lurch and weave. To them, the roadcut is a portal, a fragment of a regional story, a proscenium arch that leads their imaginations into the earth and through the surrounding terrain. - John McPheeIf I'm going to drive safely, I can't do geology. - John McPheeCheck out my Blog for more fossils I've found: http://viewsofthemahantango.blogspot.com/ Link to comment Share on other sites More sharing options...
hitekmastr Posted October 11, 2012 Author Share Posted October 11, 2012 All the rock in St. Clair is Pennsylvanian in age and terrestrial in nature. You won't find marine fossils in the shales or sandstones because it was a flood plain/estuary. What you found is a quartz infilling of a crack in sandstone. I can't explain why it looks like vertical lines but I've found enough my self to recognize it. I still believe this is Arenicolites - the trace of the fossil worm - it is always u-shaped and there are several exact replicas so I'm inclined to believe that the fact that this exact pattern is replicated as the U-shaped burrow confirms that this is the worm. Having said that, the fact that this was recovered from St. Clair doesn't mean it is from the coal swamp or even Carboniferous, since this was recovered from sandstone dumped at the top of the pits, probably from the mining operations and a lot of those rocks are not shale but are different types of rocks and probably from different formations/periods. Link to comment Share on other sites More sharing options...
araucaria1959 Posted October 11, 2012 Share Posted October 11, 2012 The last two pictures show that the structure in question "goes around the corner", i.e. this is not a linear structure like a crinoid stem or a burrow filling would be, but it seems to be a planar structure, penetrating the stone (if I interprete the last two pictures correctly). Otherwise, it would not be possible to see the structure from all the four sides of the stone. So I agree with Scylla: a rock fracture infilled with crystals. I have seen many of them, but can't show pictures since I never collected them. Sorry, I know that's not a good message and maybe I'm wrong - but that is how I understand the pics. araucaria1959 Link to comment Share on other sites More sharing options...
AgrilusHunter Posted October 12, 2012 Share Posted October 12, 2012 The last two pictures show that the structure in question "goes around the corner", i.e. this is not a linear structure like a crinoid stem or a burrow filling would be, but it seems to be a planar structure, penetrating the stone (if I interprete the last two pictures correctly). Otherwise, it would not be possible to see the structure from all the four sides of the stone. So I agree with Scylla: a rock fracture infilled with crystals. I have seen many of them, but can't show pictures since I never collected them. Sorry, I know that's not a good message and maybe I'm wrong - but that is how I understand the pics. araucaria1959 I agree with aruacaria and Shamalama, I looks to be a mineralization layer of some kind. "They ... savoured the strange warm glow of being much more ignorant than ordinary people, who were only ignorant of ordinary things." -- Terry Pratchett Link to comment Share on other sites More sharing options...
hitekmastr Posted October 25, 2012 Author Share Posted October 25, 2012 (edited) The last two pictures show that the structure in question "goes around the corner", i.e. this is not a linear structure like a crinoid stem or a burrow filling would be, but it seems to be a planar structure, penetrating the stone (if I interprete the last two pictures correctly). Otherwise, it would not be possible to see the structure from all the four sides of the stone. So I agree with Scylla: a rock fracture infilled with crystals. I have seen many of them, but can't show pictures since I never collected them. Sorry, I know that's not a good message and maybe I'm wrong - but that is how I understand the pics. araucaria1959 I've collected two of these now and have seen several others that I didn't collect - they are all identical so they are not anomalous. Also, I found several references to Arenicolites so I still believe that's what these are but of course I could be wrong and if I'm wrong then this is just a layer of quartz crystals in the rock! Edited October 25, 2012 by hitekmastr Link to comment Share on other sites More sharing options...
Just Bob Posted October 25, 2012 Share Posted October 25, 2012 I have found rock fractures infilled with quartz crystals at St. Claire I have to agree with Gus, I have also seen fractures filled in with quartz at St. Claire. "It is difficult to get a man to understand something when his salary depends upon his not understanding it." Upton Sinclair Link to comment Share on other sites More sharing options...
hitekmastr Posted October 26, 2012 Author Share Posted October 26, 2012 I have to agree with Gus, I have also seen fractures filled in with quartz at St. Claire. Well, ok - can't dispute those more experienced than me - if the consensus is that this is a quartz vein, I'll accept the consensus... Link to comment Share on other sites More sharing options...
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