Are these fossils?

[jeffmo]

A friend found these two items in Northwest Arkansas/SW Missouri in a stream bed.

Wondering what they might be.

and second item similar size without scale, sorry.

Thanks for any comments.

Edited October 29, 2021 by jeffmo
NW Arkansas not NE

[Tidgy's Dad]

Extremely good examples of layered concretions, especially that first one.

[Fossildude19]

Agreed - these are Concretions.

[jeffmo]

Very good. Thank you.

I don't suppose there is any way to guess how old they might be?

It would be nice to be able to tell the finder that they started accreting

around the time of dinosaurs or something

[FranzBernhard]

2 hours ago, jeffmo said:

I don't suppose there is any way to guess how old they might be?

Its difficult, indeed.

 

However, you can get a maximum age, if you know what host strata they were found in. Maybe someone familiar with the geology of the area will comment.

 

Franz Bernhard

[Rockwood]

6 hours ago, jeffmo said:

Very good. Thank you.

I don't suppose there is any way to guess how old they might be?

It would be nice to be able to tell the finder that they started accreting

around the time of dinosaurs or something

A quick check online would seem to indicate an earlier start on these. They likely form in a length of time that would look insignificant when compared to the geologic periods seen on color coded maps, but such maps are available.

To cast a larger net/longer time period over it, Paleozoic I think would catch it. 

[Fossildude19]

 You can easily direct the finder to this topic for further explanation:

 

 

[jeffmo]

Thanks for all the help.

What an interesting group you all are!