Mt Pleasant Mills (PA) fossils

[CamelbackMike]

These pictures are part of a large slab from the quarry at Mt. Pleasant Mills, PA.  What is the fossil below the quarter in the first picture?  Any idea what brachiopod is in the second pix?

 

Thank you,

Mike

 

[Peat Burns]

The first is genus Leptaena, a brachiopod.

[CamelbackMike]

Thank you Peat.  I did not realize brachiopods also had that concentric circle shape !

[Fossildude19]

Nice plate!  

 

The second one looks like a possible strophomenid brachiopod - something like Chonetes sp maybe?

 

According to this Geologic bedrock map, the area in Snyder county has Devonian, Silurian, and some Ordovician aged outcrops. 

 

@Shamalama can probably tell you what kind of brachiopod for sure. 

Regards,

[Plax]

looks a bit like the Rose Hill Iron, Silurian. Did you find any Calymene trilobite frags?

[Shamalama]

THe Quarry in Mt. Pleasant Mills (assuming you are talking about the one just NW of the town) is located in Tonoloway and Keyser formation rocks. The Tonoloway is Upper Silurian in age while the Keyser is transitional between the Upper Silurian and Lower Devonian. The quarry is also close to boundary with the Onondaga Formation which is lower Devonian. It's located on the side of an anticlinal limb and has some second and third order folding going on so the rock should be layered but lots of folds and tilted beds towards the southeast. Looking at the pictures it appears the rock type is either chert, sandy limestone or limy sandstone. That would lead me to think it came from the Onondaga beds or upper Keyser formation. 

 

That establishes the age to be Lower Devonian and likely a part of the Helderberg fauna. The Paleontology of New York (Vol. 3) has a one species listed in the Genus Chonetes which I doubt is what you have shown in your second picture. The Genus Chonetes becomes more common and diverse during the middle and upper Devonian.  the shell is larger so it could also be a valve from the Genus Schuchertella, Orthothetes, Xystostrophia or Strophomena, all of which look similar.

 

Your first picture looks to have a Leptaena sp. valve in the middle and two partial Leptostrophia sp. shells to the left of it.

 

[Fossildude19]

Thanks for taking a look, Dave.

I knew you would have the necessary info.  

Regards,

[Peat Burns]

On 11/9/2016 at 4:12 PM, CamelbackMike said:

Thank you Peat.  I did not realize brachiopods also had that concentric circle shape !

No problem.  That's one of my favorite brachiopods!

[Jeffrey P]

I was in that quarry back in June ( a very hot sunny day I recall) and found a number of brachiopod shells on rocks that looked similar to those. I was told it was the Upper Silurian Tonoloway Formation. If you saw a lot of wavelite crystals the you were probably in the same place. My friend, Tim found this gastropod shell which ended up giving me.

[CamelbackMike]

Thank you everybody for the information.  It was collected at a spot  only part way up to the top of the hill & the wavelite spot.  Next time I am in the quarry I might just start out there first.

 

Now all I need to do is get this 40 lb. cubic foot chert/limestone piece down to a manageable size. :-)