Sunday 7th September 2014
The next event will be on the 17th of September with Chris Darmon's talk “Iceland: Where geological processes happen in real time”
Tuesday 22nd July 2014
The next event will be on August 23rd
The next event will be on the 17th of September with Chris Darmon's talk “Iceland: Where geological processes happen in real time”
The next event will be on August 23rd
The last indoor meeting was a mineral evening led by Bill Bagley. The evening commenced with a talk by Bill about minerals and how to identify them. The talk was accompanied with some super photos of minerals. Bill had also brought in some lovely specimens from his collection. In the second half of the meeting members took part in a quiz in which they had to identify unknown minerals based on information provided. A most enjoyable evening was had by all.
The next meeting is the evening field trip which will be held at Gilfach nature reserve near Rhayader where we shall look at the geology. Meet in the car park at Gilfach at 6.30pm.
The talk on “Fracking” given by Roy McGurn was both enjoyable and controversial. He commenced by talking about the “Spindletop” oilfield in Texas that was discovered on top of a salt dome in 1901. This marked the birth of the modern petroleum industry and had an enormous effect on world history and revolutionised industry and transport.
“Fracking” is a process that combines two technologies, hydraulic fracturing and direct drilling and is used to extract natural gas or oil from deep reserves below ground. The process allows energy companies to access previously unavailable energy sources. During the process water is mixed with sand and chemicals and the resultant mixture is injected, at high pressure, into a wellbore. This produces fractures in the deep rock formations along which the gas can migrate. The first experimental use of this method was in 1947 and commercially used in 1949 so it is not a new technology.
The method has huge potential benefits for energy but also has many environmental and health related consequences. It was these aspects that led to long debate at the end of his talk.
The next meeting will be on Tuesday 17th June when Bill Bagley will hold an evening looking at minerals.
The May 2014 fieldtrip was led by Tony Thorp on and around Gaer Fawr Hill near Guilsfield, on the western flank of the Guilsfield anticline. We were near the top of the Gaer Fawr Fm (Ordovician, Caradoc), a shallowing-up sandstone with abundant fossils, as seen in the small quarry at the nature reserve car park. This hard sandstone forms the hill. Above this in the steeply dipping sequence is the softer Dolhir Fm (Ashgill), which has now eroded to a valley. The Ordovician is then topped by the Nod Glas, a thin horizon of soft black shale, which we saw in the stream banks at the valley bottom. Above this in the sequence is the very hard Powis Castle Conglomerate, a beach deposit, now forming a ridge, along which we walked, looking across the eroded valley, at Gaer Fawr Hill. All these features were beautifully evident on a lovely dry day, with additional features to be seen in the stream bed (bentonites, evidence of faulting, and limestone). The day finished with a walk to the top of the iron age hill fort, through woods of stunning bluebell display.