mattandy84 Posted March 27, 2016 Share Posted March 27, 2016 Hello all! I found this strange wavy rock in one of my Austin TX ponds. Anyone have a guess to what it is? Link to comment Share on other sites More sharing options...
ynot Posted March 27, 2016 Share Posted March 27, 2016 stromatolite. Tony Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
vonfatman Posted March 27, 2016 Share Posted March 27, 2016 Interesting fossil. I can see why you picked that one up! Bob Link to comment Share on other sites More sharing options...
grandpa Posted March 27, 2016 Share Posted March 27, 2016 I believe what you have here is a piece of banded chert. The ridges and dips are due to the differentiation in hardness and thus erosion rate between the various layers. 2 Link to comment Share on other sites More sharing options...
JohnJ Posted March 27, 2016 Share Posted March 27, 2016 I believe what you have here is a piece of banded chert. The ridges and dips are due to the differentiation in hardness and thus erosion rate between the various layers. Grandpa is right; this is a classic piece of Central Texas, differentially weathered banded chert. The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
Herb Posted March 27, 2016 Share Posted March 27, 2016 I agree with jnot, stromatolite "Absence of evidence is not evidence of absence"_ Carl Sagen No trees were killed in this posting......however, many innocent electrons were diverted from where they originally intended to go. " I think, therefore I collect fossils." _ Me "When you have eliminated the impossible, whatever remains, however improbable, must be the truth."__S. Holmes "can't we all just get along?" Jack Nicholson from Mars Attacks Link to comment Share on other sites More sharing options...
ynot Posted March 27, 2016 Share Posted March 27, 2016 I believe what you have here is a piece of banded chert. The ridges and dips are due to the differentiation in hardness and thus erosion rate between the various layers. Grandpa is right; this is a classic piece of Central Texas, differentially weathered banded chert. I do not see the conchoidal fracture that I would expect from a chert. Tony Darwin said: " Man sprang from monkeys." Will Rogers said: " Some of them didn't spring far enough." My Fossil collection - My Mineral collection My favorite thread on TFF. Link to comment Share on other sites More sharing options...
abyssunder Posted March 27, 2016 Share Posted March 27, 2016 I'm in the banded chert camp. A very nice example! Looks to glassy for Stromatolite, in my opinion. " We are not separate and independent entities, but like links in a chain, and we could not by any means be what we are without those who went before us and showed us the way. " Thomas Mann My Library Link to comment Share on other sites More sharing options...
JohnJ Posted March 27, 2016 Share Posted March 27, 2016 I do not see the conchoidal fracture that I would expect from a chert. Tony Several of the photos show 'chips' in the chert where you can see the interior rock. This is a very typical piece for the Austin, TX area. Some of the chert nodules around here develop a chalky cortex that can vary in texture and thickness. I've often used the whole rocks to illustrate how banded chert can look completely different on the inside vs. the outside...by giving them a good whack with a hammerstone to knock a flake off. 4 The human mind has the ability to believe anything is true. - JJ Link to comment Share on other sites More sharing options...
will59 Posted March 28, 2016 Share Posted March 28, 2016 If you knock a flake off and it fractures conchoidally, then I would say it's chert. However, I'm no expert when it comes to stromatolites. Link to comment Share on other sites More sharing options...
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