MYSTERY OBJECTS

[Stanley]

Perfect answer. I learned a lot from THIS.

[Stanley]

What and where?

[Stanley]

Any time now?

[Tizer]

Anthony Gormley mis-shapes?

[Stanley]

Sorry Peter no, but these are right up your street.

[PanBiker]

Are these massive Ammonites or relatives?

[Stanley]

Getting warm Ian but not ammonites. They are a recognised geological occurrence. That's why I thought Peter would be on it straight away.

[PanBiker]

Magma ejections?

[Stanley]

Sorry Ian.... No.

[Tizer]

The objects don't seem to fit in with the sandy environment so I suppose they could be glacial erratics carried far from their original location. The curious shapes could have been the result of scouring as they were moved along by the glacier. Another possibility is that they were shaped by wind erosion in a desert environment. And you get some strange shapes in blocks of granite eroded on the top of Dartmoor.

[Stanley]

A big clue Peter. Far from suffering from erosion, this class of rocks grows. These are not in the UK.

[chinatyke]

Something in my head is telling me "Tufa" but I don't know why!

[Stanley]

No Graham but the name of them is very similar to that.

[PanBiker]

I have found out, but I had to Google it, fascinating.

[Tizer]

Mrs Tiz suggested stromatolites but that word is nothing like tufa.
A similar word? Tuff is a rock formed by accretion of volcanic ash - is that it?
So-called `cannonball concretions' can form too but they are usually spherical, hence the name.

[Stanley]

Referred to by some as 'living rocks' because they grow and change shape.

[Stanley]

I'll have to knock this one on the head. They are Trovants and are found in Romania. See THIS for a more complete explanation.



Let's try another one. What is this called and what's it used for?

[Tizer]

I'd never heard about the `trovants' but find they are concretions cemented by calcium carbonate. In sandstones and gritstones the individual quartz grains are cemented together by the calcium carbonate or silica that was dissolved in the water in which they formed sediment. Carbonate indicates formation in shallow water and silica in deep water - it's related to the type of shell formed by organisms in shallow or deep water. The trovants exhibit concentric rings when split open and this is typical of concretions which form by gradual accretion over long periods of time. The trovants have probably formed under unusual conditions which have caused the carbonate cement to migrate to the surface, forming a skin. Quarrying has exposed them to the elements and led to further changes. There's more information here... ScienceAlert.com

It was a good mystery object!

[Stanley]

Thank you Peter. Now how about the wheels?

[Big Kev]

A gun carriage?

[Stanley]

No Kev but you are in the right field......

[Tizer]

To carry a battering ram?

[Stanley]

So close but no Peter. (It would have done for that!)

[Big Kev]

Is it just for carrying big canons?

[Stanley]

Yes it is Kev, but tell me how and give it a name.