AGG Malvern Hills Field Trip Sept 13 -15th 2019
AGG Malvern Hills Field Trip Sept 13 -15th 2019
Leader: Moira Jenkins
by Dr. R L Bromley
Perfect weather, interesting geology and plenty of discussion. A very lively weekend led by Moira’s enthusiasm for her area.
Some of us had been to the Malverns about 12 years ago so Moira was determined not to cover the same ground. She achieved this feat by persuading local groups and friends to scramble around old quarries clearing debris and rubbish so that we could visit all the exposures that could explain so much more than most visitors could see. The group photo was taken in the garden of a friend who even extended the offer of using their facilities for those of us who had been imbibing at lunchtime!
There were lots of photos taken of the geology, some samples collected (even fossils!) and hopefully some of us will remember what we have seen to encourage other groups to visit such an interesting area.
Thank you Moira and all the volunteers.
The Group at Scar Quarry
Information about the geology from Moria Jenkins.
Malvern Geology Timescale
BGS geology maps Worcester and Tewkesbury sheets.
OS 1: 25,00 map.
A cross section in the area of British Camp showing the underlying structure with that part of the hills thrust to the west.
Ice Age History of the Colwall Valley.
The Mathon River is the valley which can be seen from the hills.
The diagrams of the former Mathon River are from the EHT Geopark Way trail guide.
A spilitic lava from Clutter’s Cave
The field of view is 3mm from top to bottom. This is a thin section of a spilitic basalt from Clutter’s Cave. Spilitic lava is enriched in sodium and is formed when basalt reacts with seawater. When the lava erupted on the sea floor it contained gas bubbles, vesicles, in which crystals have since formed. In the picture the radiating structure within these vesicles can be seen. This is known as variolitic or spherulitic texture.
The thin sections of the Warren House Formation are those made by John Platt in the 1930s and still held at Aberystwyth University. Thin sections were photographed down the microscope at Aberystwyth University from the collection of thin sections held there. Denis arranged for me to photograph some of these down Bill Perkins’ microscope, some years ago.
The plan of the trenches at Martley gives an idea of the complicated geological structure there. Two of the trenches are being kept open.
Martley trenches plan produced by John Payne of EHT and used in OUGS Proceedings paper.
Malcolm Butler
Seismic Sections
A brief glimpse of the extremely interesting talk Malcolm gave at the Martley Village Hall (home of the Teme Valley Geological Society). There wasn’t time to look at the amazing sections in detail as the sun was shining and we had real rocks to explore. If anyone would like to delve deeper (a pun!) into the lower levels beneath the Malvern Hills area, please consult Malcolm.
The figures above are an uninterpreted composite E-W line from west of the Malverns to Stratford, a base map (which has the 1:625,000 outline geology on it) and three figures from his recent paper, showing his interpretation.