Hi k. :) The mudstone was formed in a shallow sea and is sometimes called shale. However in shale is more compressed than this sedimentary rock. The shells are what remains of ancient creatures that settled and died millions of years ago. The spot of blue you see is from the base of an abalone ancestor's shell where the iridescent layer wasn't quite worm away on that end. Above that blue is another color along the outer edge of a shell, but that is most likely a stain from something that leached into it from above.
These cobbles are just gorgeous and endlessly interesting. You can only collect small amounts along the shore, by law. Happily they are protected from bigger collecting operations, and the whole area is a protected beach for seal lions.
What is that amazing roundel of blue in the middle? And how is that formed?
ReplyDeleteHi k. :) The mudstone was formed in a shallow sea and is sometimes called shale. However in shale is more compressed than this sedimentary rock. The shells are what remains of ancient creatures that settled and died millions of years ago. The spot of blue you see is from the base of an abalone ancestor's shell where the iridescent layer wasn't quite worm away on that end. Above that blue is another color along the outer edge of a shell, but that is most likely a stain from something that leached into it from above.
ReplyDeleteThese cobbles are just gorgeous and endlessly interesting. You can only collect small amounts along the shore, by law. Happily they are protected from bigger collecting operations, and the whole area is a protected beach for seal lions.