Tuesday, December 14, 2010

Mahantango Hash Plates

In places the Mahantango is fairly limited in fossil content and what is found is restricted to thin layers or lenses that feature a large quantity of shells. These are often referred to as "Hash" layers as the fossils are generally overlapping one another and picking one shell out of the crowd can be difficult. Usually these type of occurances form as lag deposits due to currents or maybe a storm washes a bunch of shells into a lower lying area. Whatever the case they can make for interesting looking assemblages. Here are a few that I've recently found at different locations within the Mahantango.

I found this piece on a pile but could not locate more. Front side has lots of Chonetid type brachiopods.

Back side has a Brachiopod/Pelecypod mix

This piece fascinated me when I saw this side. It's a current deposited pile of Chonetid type shells. Cross section view:

Head on view:

Another angle:

A mix of Spirifer and Chionetid shells with some slight distortion due to geologic pressures.

A mix of small Pelecypods. Some of the shells have a silvery coating on them... Hematite perhaps?

At one locality there is a layer of this limestone Coquina of broken shells. Likely formed along a surf zone along the coast. Evidence of temporary shallowing?

No comments:

Post a Comment