Dorset Petrified Wood

[dhiggi]

Found this sticking out of a mud slide near Golden Cap on the Dorset coast. Certainly looks like wood, it doesn’t feel as hard as stone but harder than wood, I suppose like coal. 
Is it definitely petrified and is anyone able to speculate on age, possible species etc?

 Thank you in advance 

[daves64]

Kind of looks like it's partially carbonized. 

[dhiggi]

5 minutes ago, daves64 said:

Kind of looks like it's partially carbonized. 

So a much shorter time scale then?

[sharkdoctor]

Not really. Carbonized wood just hasn't been mineralized. That is not necessarily a function of age.

[FranzBernhard]

Is it lightweight for its size? What happens if you try to ignite a small splinter?

The first pic looks like some low-grade(?) jet (Gagat), and I can still see some growth rings (not sure?). You have also a very interesting fold in there!

Some Styrian coalified wood:

Coalified wood from Styria (pdf, 3.7 MB, in German)

Franz Bernhard

[dhiggi]

2 minutes ago, FranzBernhard said:

Is it lightweight for its size? What happens if you try to ignite a small splinter?

The first pic looks like some low-grade(?) jet (Gagat), and I can still see some growth rings (not sure?). You have also a very interesting fold in there!

Some Styrian coalified wood:

Coalified wood from Styria (pdf, 3.7 MB, in German)

Franz Bernhard

Definitely lightweight for a rock its size, not much heavier than if it were actually wood I suppose. 
I’ll have to wait until I’m home in a few days to try burning some. 
 

Not even sure if it’d be possible but the last picture shows what look like the impressions of ammonites (to the right)

Maybe just the mind playing tricks 

[FranzBernhard]

4 minutes ago, dhiggi said:

Definitely lightweight for a rock its size, not much heavier than if it were actually wood I suppose. 

Definitely coalified than (not petrified)! How far away is this site from Whitby? Such coalified wood has a density of around 1.3 g/cm³, a little bit more dense than wood, but much less dense than usual rocks (around 2.65 g/cm³).

Are you able to collect more?

 

8 minutes ago, dhiggi said:

Maybe just the mind playing tricks 

No, no, these seem to be real impression . Very interesting! Look out for more specimens please .

 

Franz Bernhard

[dhiggi]

17 minutes ago, FranzBernhard said:

Definitely coalified than (not petrified)! How far away is this site from Whitby? Such coalified wood has a density of around 1.3 g/cm³, a little bit more dense than wood, but much less dense than usual rocks (around 2.65 g/cm³).

Are you able to collect more?

 

No, no, these seem to be real impression . Very interesting! Look out for more specimens please .

 

Franz Bernhard

Thanks for the info!

Whitby is our usual stomping ground, but we’re holidaying on the south coast (the UK’s other stretch of Jurassic coast)

Planning on hitting different beaches but we’ll keep a look out now that we know what to look for.

[TqB]

Unidentifiable coniferous wood is common in the Lower Lias around there, and if not in a nodule tends to be more like lignite. That's a nice piece, closer to Whitby jet at least in appearance. A Golden Cap mudslide is probably largely made of Seatown Marl Member clay (Green Ammonite Beds). That's lower Pliensbachian, Davoei Zone - the top of the Lower Lias. 

 

Have fun, haven't been for ages and wish I was there!

Edited August 19, 2020 by TqB

[dhiggi]

Thank you @TqB, glad I pulled it out now; with only a hammer and chisel it was quite a challenge in the awful sticky clay/mud down here. With that and the time spent cleaning it up I’d have been disappointed to hear it was only a bit of modern wood