Saturday, 26 July 2014

Wilshire Geology Group AGM - Thursday 31st July

Wiltshire Geology Group invite everyone to its AGM
7 p.m. on Thursday 31st July.
Come and find out what we have done in the last year.
Wiltshire Wildlife Trust
Elm Tree Court, Long Street, Devizes SN10 1NJ

Tuesday, 15 July 2014

Jurassica Dinosaur Museum plans

A meeting has been held to discuss a £60m project to convert a disused quarry into a dinosaur museum. The scheme, called Jurassica, would be built in Portland, on Dorset's Jurassic Coast, and would open in 2019 or 2020.
Read more

Thursday, 10 July 2014

July 15th - Forensic Geology

WRGS -  Forensic Geology: The Applications of Geology to Policing & Law Enforcement
Dr Laurance Donnelly
15 July - 6:30pm (refreshments from 6pm)
Venue: Atkins, The Hub (Ground Floor), 500 Park Avenue, Aztec West, Almondsbury, Bristol, BS32 4RZ.

Wednesday, 9 July 2014

Data stored in Corsham's mines?

Corsham's mines could become 'Europe's largest data reservoir'

Fossil Foray - Writhlington - October 27th

The Somerset Earth Science Centre is organising a fossil foray at Writhlington Batch for the Mendip Rocks! Festival 2014. This will be in partnership with Radstock Museum. This will be for local families and is often well attended. It will be on Monday 27th October 2-4pm. This is a message to ask if there are any geologists out there that would like to come along and help identify peoples’ finds!
If anyone is interested in volunteering for a fun afternoon, please contact the Centre.

Tuesday, 8 July 2014

New book: 'Geology, Landscape and Building Stone around Bradford on Avon, Wiltshire'

By Isobel Geddes, author of the popular 
'Hidden Depths; Wiltshire's Geology and Landscapes'


Copies are £3.00 and available from:-
Ex Libris Bookshop, 11 Regents Place, Bradford on Avon 
Bradford on Avon Museum
Bradford on Avon Library  
Bradford on Avon Tourist Information Centre 


Tuesday, 1 July 2014

Is this a mud volcano?

One of our Bath GS members sent this prior to this Thursday's talk about mud volcanoes.
 These occur at just one horizon, close to the top of the clay/lime bands, Lias, Lyme Regis. Locally they are known as sunstones. They outcrop near Charmouth at beach level, exposed at a very low tide.

Extra info:- The rock is of about the size and proportion of an old style galvanised steel dustbin lid. I think we see two processes here. Firstly a precipitation of carbonate within the surface sediment as a consequence of methane escape. This results in a slight dome around the vent. Secondly the flow of fluids carrying sediment from below and trickling down the slope as meanders, with the loss of gas these meanders stop in a consistent distance.

Reply:
This could be a septarian concretion - so probably composed of calcite. The radial cracks are a source of some argument - whether they have formed through dewatering / contraction of the sediment or some other process. The cracks will probably also be filled with calcite crystals, sometimes other minerals (siderite, dolomite, barite, quartz etc).

Photograph above of a somewhat similar nodule from the Carboniferous of NE England.

More thoughts: It is a septarian nodule on, I suspect, Monmouth beach. In fact it is a Birchi nodule from the Bichi bed in the Charmouth Mudstone formation and just in this area the beef calcite tends to grow in this very symmetrical fashion. Locals call them 'sunstones' and I think they feature on Ian West's site. The geochemistry behind beef formation is very complex and is, I believe, related to very rapid burial and therefore pressures in poorly consolidated muds that have a high organic/methane content and that was happening at that time.