Could it be cut sections of fossilised tree trunks?

[Americo]

During a visit to a stream between Empangeni and Eshowe in KwaZulu-Natal, South Africa (we found a series of circles on mudstone. I wonder if they are cut sections of fossilized tree trunks. Below there are two photos for your perusal.

 

Thank you in advance for any information or personal opinion.

 

Regards,

 

Americo Bonkewitzz, PhD

[-AnThOnY-]

They are not wood. Most likely some iron concretions/nodules

[Auspex]

I agree that these are bisected concretionary structures.

[indominus rex]

They look geologic to me. Regards and welcome to TFF.

[Tidgy's Dad]

Hello, and a very warm welcome to TFF from Morocco. 

I see iron and sulfur concretions as well. 

[Auspex]

Here is one that was not sheared in half:

 

If you pick it up, you will find that it is an irregular sphere, and if you split it, you will see the same cross-cut pattern.

 

That strata was laid down in a very anoxic environment, rich in sulfur and iron. I would love to know its age...could be near the Permian/Triassic boundary!

[abyssunder]

I'm not a geologist, but I suppose that it might be something in the realm of volcanogenic material (volcanogenic sandstone - dolerite - clay_ line), so I agree with the others.

 

" Rydalvale, at Ukulu Properties (Pty) Ltd., Empangeni: A black montmorillonitic clay loam to clay, about 40 cm thick, on moderately porous yellowish brown weathering dolerite. This soil series represents 1,7% of the industry's soil (Beater1). " - in P. K. Moberly, 1972.

 

pictures from here