[zeestephen]

Re: Oil Shale

Thanks for your very interesting note.

I knew I should have researched that before commenting.

I assumed the organic material descended to the shale at the same time the shale was ascending back to the surface

The freshwater lake is a total surprise.

I recall that several times in geologic history salt water oceans have pushed all the way to the Rockies.

Is there also oil shale in the Burgess Shale deposits in the Canadian Rockies?

[crusty old prospector]

The Burgess is a much older shale. It was deposited under the same anoxic conditions, thus it has the black color instead of being gray. The problem with it as being a source rock for petroleum is that the organisms that form it aren’t the ones that upon burial, are converted to kerogen. The Burgess is known for its preservation of beautiful species of early life, specifically trilobites, which look like large doodlebugs. If I remember correctly, the proper algae that is the key component for kerogen hadn’t evolved yet. The only organism around then that is documented to be potential source material is called a graptolite.