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age of Marl?


LeesKeys

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I went on a very pleasant hike last weekend on the Island Creek Trail in the Croatan National Forest near Pollocksville, NC. In one spot along the creek the embankment is layered with about 15 feet of fossil shells. Trying to get an idea of the age of these deposits. Pleistocene? Miocene?

island creek.jpg

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Finding a geologic map of your area (there are plenty online) will allow you to zoom in and find the exact spot and the age.

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Thomas.Dodson

Geologic maps of NC indicate the Island Creek Trail is River Bend Formation, Middle to Late Oligocene.

 

North Carolina Department of Natural Resources has a very handy GIS integrated geologic bedrock map.

https://ncdenr.maps.arcgis.com/apps/MapSeries/index.html?appid=a8281cbd24b84239b29cd2ca798d4a10

 

They also have full sized PDFs.

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I agree, this looks like the River Bend Formation. If you see abundant large oysters in the area it is the Pollocksville Member of the Belgrade Formation.

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Tertiary period- looks like it could have been laid down anywhere from 66 to 2 million years ago. Anyway to narrow it down further?

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5 hours ago, Al Dente said:

I agree, this looks like the River Bend Formation. If you see abundant large oysters in the area it is the Pollocksville Member of the Belgrade Formation.

Concur. Pollocksville Member of the River Bend Fm. It’s the type locality, actually.

 

 

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4 hours ago, LeesKeys said:

Anyway to narrow it down further?

It was mentioned that this was the Oligocene River Bend Formation. Oligocene is 33.9 to 23 mya. More specifically, the formation is Middle to Late Oligocene so you can probably narrow that even more to roughly 29-23 mya. 

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Thanks. Deep time is just remarkable to me, especially when I can see and touch it. About 10 years ago my family visited the Grand Canyon and did the mule ride down to the bottom.  I recall rubbing my hands over a section of tortured-looking rock that was about a billion years old! Awesome and humbling!

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