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Kevofossilhntr

Identifying layers of sediment

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Kevofossilhntr

Need some help identifying layers of fossil sediment along a steep cliff side, having a hard time distinguishing time zones. Thank you! 

11C0BD5E-DEF3-4625-8490-2629352C34EC.png

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Kane

That’s a lot of fallen slump. You might have to expose the rock and say something about the location first.

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Kevofossilhntr

The area is Big brook NJ & the cliff side is about 40 feet down to the bottom creek bed. I can see several layers with shells & loads of belemnites sticking out about 15 feet up, just curious what layer they could be from. 

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Fossildude19

Welcome to the Forum. :) 

 

Have you seen THIS PAGE?

 

BB1.JPG     BB22.JPG

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Kevofossilhntr

No I have not seen that page, awesome thank you! 

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erose

Ugh! The geology is not so easy... That map doesn't even show the roads.

 

First, is that upstream or downstream of Boundary Road? A number of years back I researched the stratigraphy for a NYPS field guide. I talked to at least three different geologists (two from the state) and they all had different opinions about the presence or NOT of the Mount Laurel.  The strata exposed near and upstream of Boundary Road below the Navesink more closely matches the Wenonah. At least two of the geologists considered the Mt Laurel absent at the brook. They also said all the geo maps were suspect.

 

What I did learn as I worked on the field guide was that you pretty much never found a faunal list for central New Jersey that didn't lump the Mount Laurel and Wenonah together. 

 

If you are seeing oyster "beds" with Exogyra and/or Pycnodonte you are most likely looking at the Navesink.  Read closely the full descriptions of the formations and pay attention to how they manifest in the area. For instance the Mount Laurel further south is a very sandy unit as opposed to the BB area. If you don't understand the technical terms used, get a copy of a geoscience dictionary.  

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Kevofossilhntr

Awesome thank you! I’ll have to read up on some of the terms and get the geoscience book. Still kinda new in the fossil hunting scene. What layer are most of the shark teeth coming out of at big brook then if there’s most likely no Mount Laurel layer exposed? Just The wenonah? 

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erose

They come out of both the Navesink and Mount Laurel*/Wenonah. But there is a concentration coming from a pebbly lag deposit at the base of the Navesink. It is hard to find in outcrop. But about a dozen years ago some not so intelligent collectors IMHO tried mining back into the bank at a spot upstream of Boundary Road. The bank collapsed and nearly killed one of them.

 

 * Let me re-iterate: I heard different things from different people about the Mount Laurel. But considering those people were actual stratigraphers I was left a bit confused. But there was at least one good professional paper that strongly suggested that if present it is only intermittent lenses. And from personal observation the lithology exposed in most places below the Navesink more closely matched descriptions of the Wenonah.

 

I'll need to find the reference and post it here.

FOUND IT: https://www.researchgate.net/publication/291343086_Sedimentology_ichnology_and_paleoenvironments_of_the_Wenonah_and_Mt_Laurel_Formations_New_Jersey

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Kevofossilhntr

Thank you for the article! Makes more sense now distinguishing the two & yeah I would never dig into the bank of a 40ft overhanging cliff.. not that bright of an idea, luckily those people weren’t killed. I just saw the layers along the banks and was curious which ones majority of the teeth were eroding out of. 

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erose
24 minutes ago, Kevofossilhntr said:

Thank you for the article! Makes more sense now distinguishing the two & yeah I would never dig into the bank of a 40ft overhanging cliff.. not that bright of an idea, luckily those people weren’t killed. I just saw the layers along the banks and was curious which ones majority of the teeth were eroding out of. 

You are welcome. I collected the brooks over about 12-15 years from the early 80's up to about 2005 before moving here to Austin.  In all that time I think I maybe only found one or two teeth in the actual bank of the stream and that was always the lower Navesink. Every other tooth or bone fragment was sifted or surface collected off of a gravel bar, above or below the water line. 

 

I also learned to ignore the suggestions that teeth were better or more plentiful up, down or beyond any one area. Over that time I found great stuff all along the creek from well above Boundary Road to well below Hillsdale Road.  The only exception was oysters and other shelly fossils which were way more plentiful closer to, and below Hillsdale.

 

Remember the formations are all in down dip to the east so that what is high on the bank at Boundary may be at stream level near Hillsdale.

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Kevofossilhntr

Yes I did notice all the high banks are sloping downwards to the east. Ive found a few nice spots so far this is my first season there I’ve only been about 4 times. So far I found a mosasour tooth, a huge 1.5”+ sawfish rostral & I just found a vertebrae that I THINK is xiphactinus fish?? Any clue? 

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Kevofossilhntr

3BB054DA-0E7A-4726-8EBF-464B4E7FA8A7.png

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The Jersey Devil
On 4/23/2019 at 7:31 PM, Kevofossilhntr said:

3BB054DA-0E7A-4726-8EBF-464B4E7FA8A7.png

 

That’s a bony fish vert, further ID is likely not possible.

I would love to see pics of the sawfish rostral.

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Kevofossilhntr

054F98B4-9123-415B-AD0D-AC296CC2BFB6.jpeg

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Kevofossilhntr

Pictures kinda dark but this is the sawfish. I found a bunch of little small ones but this one is HUGE compared to the others 

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Kevofossilhntr

15E4EAB5-4DBC-4527-B8B6-999560FC2B92.jpeg

5A826CB8-034A-46C9-B211-FFCF45C6745B.jpeg

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The Jersey Devil

That’s a great one!

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Kevofossilhntr

Yeah I was pretty pumped when I saw it in the tray lol the root structure is all intact too luckily!

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Kevofossilhntr

The vert and the rostral were in the same shovel scoop as well which was crazy  

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