Dr Bob again
and his faithful dog Piglet who is
accompanying him in the field.
Today as we promised we're going
to show you some rocks.
My favorite rock from the Amole Arkose
is this one right here.
They're literally tons around here.
This is cryptoalgal stromatolitic
laminated limestone and the
interpretation is
that in this ancient lake a biofilm
lay down of probably blue-green algae
and either precipitated and
or trapped minerals to form have a nice
little
microphone uh this is the same thing
that happens on your teeth with dental
tartar or calculus.
Now in some definitions of the word
stromatolite,
this is stromalite, that all the
conditions have been met.
There's a biofilm and it's laying
down a mineral layer.
But other definitions of stromatolite
require that it have synoptic relief.
That means that it has to stand out
and stick out from the surrounding
topography.
The last part of it is the lamina
which is the lines of dark
and light or resistant and not resistant
rock in there.
And they do imply a periodicity; that
might have been a year,
an annual cycle, a seasonal cycle,
we don't know. In some modern examples
uh it's even been shown to track the
sunspot cycle which is about 13 years.
The cryptoalgal refers to the fact that we
do not have actual body fossils
of the algae or microbe that lay down
this rock.
So it's hidden or unknown to us.
Therefore
it's cryptoalgal. So that's kind of
everything going on here.
By almost any definition of a fossil
this is the remains of ancient
life and therefore it is a fossil. It's something that's not uncommon
here on the Amole Arkose
and this is pretty neat to look at it's
pretty neat.
Thank you, that's all for today. Other
than assuring you that no dog was harmed
in the filming of this video. Bye for now!
