Post by panamark on Sept 1, 2015 18:02:35 GMT -5
Yesterday while trying to concentrate on fishing 
, I saw this one staring at me from a gravel bar. It is beautiful I think, reminding me of some African artwork or a thumb print.
A major part of why I like this rock so much is the wonderful geological story it tells. As I understand it, looong ago, over 100 million years ago this object was part of a deep ocean floor (not at 1 mile altitude where I found it.) It was far enough offshore and deep enough that only fine mud/silt was deposited. Each layer represents some episodic event, such as an huge flood that carried a large amount of mud far offshore. Or an ice age that stopped any deposition. Over time many layers built up. But then a seismic event occurred that caused the sea floor to tilt. (Or possibly there was a change in the ocean currents that caused the deposition pattern to change. Think of how shifting blizzard winds can cause different layers and angles of snow. When the isthmus of Panama formed it divided a huge ocean in two, changing the ocean currents and having major impact on the entire world climate.) Anyway, deposition resumed but on a different horizon. And in this case the difference was beautiful.
, I saw this one staring at me from a gravel bar. It is beautiful I think, reminding me of some African artwork or a thumb print.A major part of why I like this rock so much is the wonderful geological story it tells. As I understand it, looong ago, over 100 million years ago this object was part of a deep ocean floor (not at 1 mile altitude where I found it.) It was far enough offshore and deep enough that only fine mud/silt was deposited. Each layer represents some episodic event, such as an huge flood that carried a large amount of mud far offshore. Or an ice age that stopped any deposition. Over time many layers built up. But then a seismic event occurred that caused the sea floor to tilt. (Or possibly there was a change in the ocean currents that caused the deposition pattern to change. Think of how shifting blizzard winds can cause different layers and angles of snow. When the isthmus of Panama formed it divided a huge ocean in two, changing the ocean currents and having major impact on the entire world climate.) Anyway, deposition resumed but on a different horizon. And in this case the difference was beautiful.
