Fossils found in DC?

[Jj Rollins]

In the past month or so, I've been finding these rocks which I'm starting to think contain fossils, or trace fossils.

What exactly? Perhaps you can tell me. Obviously I'm new here but also, new to paying attention to and researching rocks. 

These were found in Washington DC. 

 

[Emthegem]

Right off the bat, these definitely look like crinoid stalks. They are essentially like underwater feathered flowers that filter the water for nutrients, and this is the stem of the crinoid. Obtaining the "feathery" components (AKA the 'crown' of the crinoid) is typically very rare.

I just did some quick research and it seems like Washignton D.C.'s formation range is in the Tertiary (~2 to 65 MA) and Cretaceous periods (~65 to 145 MA). (source: https://pubs.usgs.gov/bul/0967/report.pdf)

After looking online, your fossils seem to match up quite nicely with other crinoid stems from the late Cretaceous period (somewhere between 65-100 MA), so thats my first educated guess.

I could be wrong though, if anyone else has anything to say please feel free to correct me!

Hope that helped though! 

 

I stand corrected, they seem to likely be trace fossils oops. 

 

-Em

 

[Rockwood]

2 hours ago, Emthegem said:

please feel free to correct me!

Sorry. But I think correction is in order.

The best I can do is possible trace fossils, but the evidence is weak even for them I'm afraid.

The DC area is known for dinosaur tracks, and some body fossils.

[JohnJ]

I agree these do not appear to be crinoids.  

[Emthegem]

6 hours ago, Rockwood said:

Sorry. But I think correction is in order.

The best I can do is possible trace fossils, but the evidence is weak even for them I'm afraid.

The DC area is known for dinosaur tracks, and some body fossils.

6 minutes ago, JohnJ said:

I agree these do not appear to be crinoids.  

Ah okay, well this is awkward hahah

 

[Rob Russell]

Welcome to the forum, JJ.  

 

Maybe some “in focus” pictures would be of use in making a better assessment? 

 

They don’t strike me as typical crinoid columns, either. 

[Plax]

Paleozoic fossils are found in DC area gravels and river cobbles.

[WhodamanHD]

These quartzite trace fossils may come from the Cambrian-aged Antietam formation. They got worn out from central/western Maryland and got redeposited.

[Rockwood]

6 hours ago, Emthegem said:

Ah okay, well this is awkward hahah

It shouldn't be. Just own it, learn from it, and move on.

I should know. 

[FossilDAWG]

3 hours ago, Rockwood said:

It shouldn't be. Just own it, learn from it, and move on.

I should know. 

As do we all.  You are in good company.

 

Don

[EMP]

On 5/27/2020 at 12:31 AM, Jj Rollins said:

In the past month or so, I've been finding these rocks which I'm starting to think contain fossils, or trace fossils.

What exactly? Perhaps you can tell me. Obviously I'm new here but also, new to paying attention to and researching rocks. 

These were found in Washington DC. 

 

 

These are Skolithos linearis, trace fossils of annelid worm burrows. Judging by the types of rocks they look to be from the Antietam Sandstone, an early Cambrian unit from the Blue Ridge Mountains. 

 

My bet is that these were eroded down from the area of Rohrersville/Harpers Ferry and transported by the river to DC, where they were deposited. Since the sandstone/quartzite of the Antietam is a very hard rock it tends to survive the long journey whereas softer shales, limestones, etc. would dissolve/disintegrate. 

 

Whether or not they were deposited in "modern" times would depend on where in DC you found them. I've found the exact same fossil in Cretaceous deposits that were eroded and deposited during Cretaceous times, and occur in beds containing Cretaceous fossils. DC also has Tertiary and Quaternary aged deposits from when the Potomac ran along a different course, most notably with a unit called the Tertiary Upland Gravel or TUG. If these are from further away from the river in a stream or garden it's probable they were actually eroded millions of years ago and not "recently."