| Collected from: |
Aust Cliffs, Gloucestershire UK |
| Period: |
Triassic / Jurassic |
| Date: |
September 2004 |
| Description: |
This looks like a lump of dried clay but the question I have is how? The Triassic beds at this location are all red sandstones laid down in a large desert basin with layers of gypsum deposited from salt pans. The Jurassic beds above these are all dark marine mud, full of fossil bivalves and the like. This is not an isolated sample, there are plenty on the beach ranging from about 2cm across up to the size of this piece at 7cm and bigger so I can be confident that this is where the piece originates. The sample is hard but when broken open shows no internal detail and is so fine that even a hand lens reveals no grain structure. So my question is what is the origin of these pieces? If they were laid down in the Triassic it would explain the sun dried clay look but in a sandy desert what would their origin be. If from the Jurassic then how come the light colour and how would it have got sun dried? If you have any thoughts then send me an email  and I will post the comments here (anonymously if preferred). P.S. I put the same questions to the S260 group on First Class and they came up with nothing, call themselves geologists! |
Index of other featured fossil and mineral samples