A new ID please

[Doug A]

Hello all and thanks for all of your support on another ID that I asked for. I am very new to this so I read this site a lot before I ask any questions to learn as much as possible about my area of hunting. However, I do find things that are beyond my paygrade that I hope you can help with.

The pics I uploaded are of what I am digging around. We had a big rain last week that washed off the big slab that I hunt beside. It is about 30 yards wide and about 100 yards long or so. The creek runs along the side of it and is a mostly sand bottom but sifting the sand is where I find coral, shark teeth and bone.

Walking in I walk on the slab and I noticed about 8 randomly circles that were raised about an inch above the surface of the slab. They are the size of manhole covers pic 1. i followed them until I found one that had something I thought was a big oyster sticking out of it in pic 2. It has drilling type marks on the perimeter of the hole and the object stuck out about 3-4". I dug it out and it was what I have in pic 3. My searching has brought the answer to be between a concretion or an egg of some sort. The dimensions are about 13" from top to bottom and a circumference of 28" or so. It weighs around 30lbs.

Any help would be appreciated.

 

[ynot]

Concretion. Too big for any egg.

[Fossildude19]

+1 for Concretion.

Regards,

[Doug A]

that is what I was leaning toward. The research I found said that something is in it which calcified and caused it to form. Is it worth busting open or what? Some people have collections of them with crabs and such in them. I don't know what would be the best thing to do with it.

 

[ynot]

There could be a fossil in it or there could be nothing left of the original.

The only way to be sure is to break it open, but there is no guarantee that will produce a nice fossil.

[M Harvey]

Where was this found?  Do you know the formation?  Definitely not an egg and I wouldn't  classify it as a concretion.   It looks like a weather rock from the picture which begs the question how did they get there and why do they have a concentric circle around them?

[ynot]

5 minutes ago, M Harvey said:

Where was this found?  Do you know the formation?  Definitely not an egg and I wouldn't  classify it as a concretion.   It looks like a weather rock from the picture which begs the question how did they get there and why do they have a concentric circle around them?

The concentric raised area around the concretion is a less mineralized part of the concretion. Kind of like a pit in a peach, the center of some concretions is harder than their outer layers.

[Doug A]

4 minutes ago, M Harvey said:

Where was this found?  Do you know the formation?  Definitely not an egg and I wouldn't  classify it as a concretion.   It looks like a weather rock from the picture which begs the question how did they get there and why do they have a concentric circle around them?

In Amory Mississippi. There is a creek down there that has the big slab I referred to. I have found crocodile vertebrae as well as a spear head. Its a neat area.

[Doug A]

I have been asked before here if I know the formation. What do you mean by that? If you could break down what you are asking I will educate myself further on the area so I can help you guys help me.

Thanks again for all that had input. if i can get it open, I will share it with the group.

[Kane]

In the simplest terms, a formation refers to a distinct band of rock linked to the age in which the sediments were deposited, and is used as a measurement in stratigraphy. Think of it like a big cake with lots of layers. If you take a look at a picture of the Grand Canyon, you can see all these bands of differently coloured and textured rock. It can take millions of years of deposited sediments and decaying organic material to make up several feet of rock. Finer divisions of a formation are called "members".

 

If I know the formation of a rock that is exposed, I know a great deal about the composition and type of rock it is, its age, and what potential fossils will appear in there.

 

One good way of knowing the age of your finds is to search online for a geological map of where you are collecting rocks. Formation information may not appear on all geological maps, but you can start digging around online for descriptions of the rocks in your area that should describe each formation in that area, such as colour, type, texture, and index fossils. It's a little like playing a forensic detective!

 

Granted, what I've just said is a gross oversimplification, but it should help in getting started.  

[Fossildude19]

Geologic map of Mississippi

 

 

 

Geology of the Mississippi Embayment.

[Doug A]

Per that map I am right on the line of the Selma and Tuscaloosa group. To the left of the TinTom waterway it is showing. The creek bed has eroded about 15' +/- down from the original line. As in its a 15' climb down to the water from ground level.

Thanks for the map, I was just about to look for one.

[Plax]

I hope it' a concretion and looks like one. Another possibility is that a rock has washed onto the bed and wallowed around in the current making itself a hole to reside in. Fine sediment from turbid high water stages would fill in the space around the wobble hole with sediment. Am in the concretion camp but wanted to mention this other possibility which I've observed in stream beds.

[Herb]

looks geologic to me also

[M Harvey]

On 9/13/2017 at 11:11 AM, Doug A said:

Per that map I am right on the line of the Selma and Tuscaloosa group. To the left of the TinTom waterway it is showing. The creek bed has eroded about 15' +/- down from the original line. As in its a 15' climb down to the water from ground level.

Thanks for the map, I was just about to look for one.

I have done some collecting at Tupelo and would say this is from the Tuscaloosa Fm.  It is characteristic of the unmodified clay layers inner bedded with sand and well rounded conglomerate rocks mostly quartzite.  It is lacking fossils except for occasional carbonized or petrified wood.  The best way to determine if it is concretions is to cut or break off a piece and see if it is solid rock.