fossils4fun Posted December 27, 2014 Share Posted December 27, 2014 Hi fossil friends, I walk by this big rock every time I go fossil hunting and I am always wondering, what are these holes? The rock is about 2 feet tall and 2 or 3 feet wide. The holes are about 4 or 5 inches across. If anyone knows I would really appreciate it, it's driving me crazy, thanks so much and have a great new year. Link to comment Share on other sites More sharing options...
Ludwigia Posted December 27, 2014 Share Posted December 27, 2014 (edited) It would help if you could post some larger, more detailed photos and also tell us something about the locality and the geological formation and age where it is lying. Was it transported there or did it derive from the local layers? Edited December 27, 2014 by Ludwigia Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
fossils4fun Posted December 27, 2014 Author Share Posted December 27, 2014 Let me try again with the pictures, I'm new at this so it may take a little while, thanks. It was not transported here, a natural formation to the area, the place is Northwest Arkansas and I have a lot of sandstone with impressions in them, I hope that helps a little. Link to comment Share on other sites More sharing options...
Auspex Posted December 27, 2014 Share Posted December 27, 2014 They could be gas bubbles that were entrained in the sediment. "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...
fossils4fun Posted December 27, 2014 Author Share Posted December 27, 2014 This is about as good as I can get it, thanks. Link to comment Share on other sites More sharing options...
TyrannosaurusRex Posted December 27, 2014 Share Posted December 27, 2014 It may just be from dripping water? That would be my guess. That or there may once have been some type of bivalve that has long since dissolved into nothing. Link to comment Share on other sites More sharing options...
Plantguy Posted December 27, 2014 Share Posted December 27, 2014 Dang that is neat looking. Is it a sandstone??? I'm guessing without hearing more that it looks like the weathering phenomena of a limestone/carbonate rock. Rain water dissolving the rock and maybe that process is enhanced mechanically by some freeze/thaw during the winter over the years.. Regards, Chris Link to comment Share on other sites More sharing options...
fossils4fun Posted December 27, 2014 Author Share Posted December 27, 2014 I'm pretty sure it is sandstone. I am really enjoying all this feedback, very interesting. Link to comment Share on other sites More sharing options...
Ludwigia Posted December 27, 2014 Share Posted December 27, 2014 I'm just guessing, since it's still difficult to recognize any details, but it may be that the "holes" were created by concretions within the sediment which have since fallen out due to weathering. Greetings from the Lake of Constance. Roger http://www.steinkern.de/ Link to comment Share on other sites More sharing options...
Missourian Posted December 27, 2014 Share Posted December 27, 2014 Most likely, it is differential weathering. If there is any variation of resistance in the strength of the rock, the weaker spots will erode out first. This can be cause by a variety of reasons. Context is critical. Link to comment Share on other sites More sharing options...
Plantguy Posted December 28, 2014 Share Posted December 28, 2014 Most likely, it is differential weathering. If there is any variation of resistance in the strength of the rock, the weaker spots will erode out first. This can be cause by a variety of reasons. Missourian, I agree. Not sure what might be holding the sand grains together--could be limey or maybe not. Saw this neat picture of a section of similar strange stuff somewhere in the state while I was out looking... https://arkansasgeological.files.wordpress.com/2013/11/2013-11-19-033.jpg I should find and have a piece of this outcrop--how I'd get it back here and where I'd put it is an entirely different matter..... Regards, Chris Link to comment Share on other sites More sharing options...
fossils4fun Posted December 28, 2014 Author Share Posted December 28, 2014 Very nice picture, I've never seen anything quite like it before. I do have a bluff with perfectly half round basketball size holes in it. I never knew what they were but I thought it might be a place where water once slapped the side. Just a thought, I may be all wrong. Link to comment Share on other sites More sharing options...
Rockwood Posted December 28, 2014 Share Posted December 28, 2014 Does not the texture within them at least pose the question algae ? Link to comment Share on other sites More sharing options...
Auspex Posted December 28, 2014 Share Posted December 28, 2014 ...Not sure what might be holding the sand grains together... I think iron is implicated; there are similar constructs to be seen in such disparate places as Calvert Cliffs and transgressive Pennsylvanian coal-zone deposits. "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...
ashcraft Posted December 28, 2014 Share Posted December 28, 2014 Could be stromatolites, which were softer and weathered out. Particularly with the one specimen with the wavy texture. Looks very algal matish to me. Brent Ashcraft ashcraft, brent allen Link to comment Share on other sites More sharing options...
fossils4fun Posted December 28, 2014 Author Share Posted December 28, 2014 Thanks so much for all the great feedback!! Link to comment Share on other sites More sharing options...
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