A broken Shell

[Shellseeker]

Pretty nice day yesterday  Sunshine, but cool, especially if the clouds blocked the sun and the breeze picked up. I was glad to have a 5 mm wet suit.  My find of the day is a nice Ursus m2.  These are rare !!! especially for me. I have found exactly 4 in 12 years of hunting.  At this size, a female or juvenile.

 

It is nice being on the river.  The effort in digging and sifting is "on automatic".  I think mostly about fossils and the Peace River.

Salt water is not all that common in the center of Florida around Fort Meade, going north. According to historical sea level data, the last time we have lots of salt water was 3-4 million years ago , and previous to that, around 12 MYAs.

When I see a sea shell in my sieve,  I always wonder WHEN did that shell contained its original inhabitant.  Was it 3 million or 12 million or maybe earlier. At a minimum , I need a shell I do not recognize in our modern assemblage of Florida shells.  Hopefully, I have some friends on TFF who can comment. @MikeR is definitely one of those...

This fragment might be Turritella magnasulcus, from the late Pliocene of the Tamiami Fm

So,  is there enough of this shell to tell us what it is ?  When was this shell being dropped?

 

[Sacha]

Jack, what's that 2nd item in your hand? I've been finding clusters similar to that at me spot in Zolfo, keep wondering about them and then tossing them back. I'm always sorry after the fact, have no idea what they might be. Some are as large as a ping-pong ball. I don't think they're bryozoans.

[Shellseeker]

I wish I knew , John. 

I was sneaking it in in case someone would be able to recognize/identify. I have been finding them occasionally mostly this size but , in a few cases larger. I have always considered them to be marine based.

I keep this one because , if you look at the small dark spot, it seemed to be agatized. Let's see if another member recognizes it. 

 

Jack

[Coco]

Could it be a limestone algae ?

 

Coco

[Shellseeker]

3 hours ago, Coco said:

Could it be a limestone algae ?

 

Coco

Thanks Coco. 

I found this website:  https://www.balticexplorer.org/en/determination/fossilien

and this photo from the website... Center of left photo... another name is possibly rhodolith

 

 

[MikeR]

Hi Jack

 

The shell is not Turritella magnasulcus which is an Upper Pliocene gastropod and you are collecting I suspect, Upper Oligocene/Lower Miocene Tampa Member of the Arcadia Formation.  I think you have Turritella tampae which Dall noted is highly variable.

 

Mike

[Shellseeker]

4 hours ago, MikeR said:

Hi Jack

 

The shell is not Turritella magnasulcus which is an Upper Pliocene gastropod and you are collecting I suspect, Upper Oligocene/Lower Miocene Tampa Member of the Arcadia Formation.  I think you have Turritella tampae which Dall noted is highly variable.

 

Mike

Thanks, Mike

You always bring me back to reality.  I attempted to find photos T. tampae on the internet , but this was the best I could do:

 

I was looking at this chart on sea levels, thinking about the peak 3-4 myas without considering the much higher peaks 20-25 mya over to the left of the  chart.  It seems

that salt water would have inundated the general vicinity of Fort Meade in the Pliocene and then again 12+ myas and stayed deeper going back.  There very likely could be a mixture of marine fossils from the Pliocene and middle Miocene and earlier.

 

[Harry Pristis]

It's my rule-of-thumb, Jack, that any marine shell this glassy, translucent-to-transparent, even in part, is eroded out of the Tampa limestone.  Similar-age silicified marine fossils are exposed in the Marianna limestone in North Florida.

[Shellseeker]

50 minutes ago, Harry Pristis said:

It's my rule-of-thumb, Jack, that any marine shell this glassy, translucent-to-transparent, even in part, is eroded out of the Tampa limestone.  Similar-age silicified marine fossils are exposed in the Marianna limestone in North Florida.

 

A great insight, Harry.  I am trying to get my thinking straight around the incidental marine fossils that show up when I am primarily seeing mammal material from the Pleistocene. I see mostly shell material that is not yet silicified and then a much smaller amount that is silicified.

These are all hints about the approximate age of the fossils I find.

Thanks

[Tetradium]

On 3/21/2021 at 10:11 PM, Shellseeker said:

Thanks Coco. 

I found this website:  https://www.balticexplorer.org/en/determination/fossilien

and this photo from the website... Center of left photo... another name is possibly rhodolith

 

 

I myself have collected modern coralline algae from florida beaches so I think it is one for sure. 

[Shellseeker]

8 hours ago, Tetradium said:

 

I myself have collected modern coralline algae from florida beaches so I think it is one for sure. 

Thanks !!! Do you think there is away to differentiate "fossil" coralline algae from modern coralline algae ? Could coralline algae form in fresh or brackish water?

[Coco]

Hi,

 

I don’t know what you mean by coralline algae, but here’s a picture of recent limestone algae I’ve sorted. They come from the maerl of Brittany (France). The maerl is a kind of marine cluster that develops by accumulation of calcareous algae and a multitude of shell fauna. The maerl is removed from the sea to amend the land before cultivating it.

 

 

The algae in the picture is about 1.5 cm. They can be bigger. i don't know if we can see difference between recent and fossil ones.

 

Coco

 

 

Edit : in this link I can understand that coralline algae is calcareous algae, isn't it ? https://fr.wikipedia.org/wiki/Maërl

Edited March 24, 2021 by Coco

[Shellseeker]

9 hours ago, Coco said:

I don’t know what you mean by coralline algae, but here’s a picture of recent limestone algae I’ve sorted

I have never heard the term before last week. In the photo above (Baltic_explorer website. It states "Pink to white, knobby or branched", at the Peace River 80 kilometers from the nearest salt water,  I have been finding the white, knobby, kind.

Quote

calcareous

• adj.
  Composed of, containing, or characteristic of calcium carbonate, calcium, or limestone; chalky.
• Partaking of the nature of lime; having the qualities of lime; containing lime; chalky: as, calcareous earth or stone.
• adj.
  Partaking of the nature of calcite or calcium carbonate; consisting of, or containing, calcium carbonate or carbonate of lime.

The Peace River has limestone, and calcium, and calcium carbonate, and calcite!!!  I have seen them all, and so far all of these derive directly from the Mio_Plio Seawater that covered the Peace River 3 or 12+ myas

Quote

Calcareous algae are a highly artificial group that constitutes calcifying members of the Chlorophyta (green algae), Rhodophyta (red algae), and Phaeophyta (brown algae) and is sometimes also used for Cyanobacteria. At present, calcareous algae are one of the most important reef builders.

Here is a photo I took of some finds yesterday:  A section of Baleen whale jaw, a partially calcite seashell, and another Coralline or Calcareous Algae. I saw about 10 of these, with this one being the largest at 2.2 cm.

This piece of Coralline Algae will whiten as it dries. I do not believe it to be modern, but instead created 3-4 mya or possibly more then 11 mya when sea water depth was very much higher than it is today. 

 

 

 

 

 

 

Adding a closeup photo:

Edited March 24, 2021 by Shellseeker

[Tetradium]

18 hours ago, Shellseeker said:

I have never heard the term before last week. In the photo above (Baltic_explorer website. It states "Pink to white, knobby or branched", at the Peace River 80 kilometers from the nearest salt water,  I have been finding the white, knobby, kind.

The Peace River has limestone, and calcium, and calcium carbonate, and calcite!!!  I have seen them all, and so far all of these derive directly from the Mio_Plio Seawater that covered the Peace River 3 or 12+ myas

Here is a photo I took of some finds yesterday:  A section of Baleen whale jaw, a partially calcite seashell, and another Coralline or Calcareous Algae. I saw about 10 of these, with this one being the largest at 2.2 cm.

This piece of Coralline Algae will whiten as it dries. I do not believe it to be modern, but instead created 3-4 mya or possibly more then 11 mya when sea water depth was very much higher than it is today. 

 

 

 

 

 

 

Adding a closeup photo:

Freshwater? Nope. Freshwater often isn't calcium rich. Most freshwater snails are fragile and easy to break - only freshwater mussels and clams come close to saltwater bivalves. Brackish? Possible if its lagoon open to the sea. I have seen Coralline algae  similar to the ones you found all the way up to Nova Scotia. The Florida keys have very high density of different coralline algae but seem like this particular one need a bit cooler seas.

 

That's one lovely whelk. On Atlantic side its very low diversity fossils with small shark teeth being rare find though after last year hurricane someone found horse teeth on the beach that I had been on in the past. 

[Shellseeker]

13 hours ago, Tetradium said:

Freshwater? Nope. Freshwater often isn't calcium rich. Most freshwater snails are fragile and easy to break - only freshwater mussels and clams come close to saltwater bivalves. Brackish? Possible if its lagoon open to the sea. I have seen Coralline algae  similar to the ones you found all the way up to Nova Scotia. The Florida keys have very high density of different coralline algae but seem like this particular one need a bit cooler seas.

Exactly the point.

I am finding coralline algae remains in what is now fresh water 50 miles from the Gulf of Mexico. My coralline algea is a fossil created about 3 mya, the last time Salt water inundated "Bone Valley". It looks to be almost exactly the same as modern coralline algae.

[Tetradium]

On 3/25/2021 at 8:14 PM, Shellseeker said:

Exactly the point.

I am finding coralline algae remains in what is now fresh water 50 miles from the Gulf of Mexico. My coralline algea is a fossil created about 3 mya, the last time Salt water inundated "Bone Valley". It looks to be almost exactly the same as modern coralline algae.

True. Always good to eliminates some options.