Monday, 20 May 2019

New Course from Dave Green

New Course from Dave Green

Geology and Landscape of Gloucestershire and surroundings 
A weekly field-based introductory course. 
No previous knowledge of geology is assumed Tuesday evenings 28thMay to 16th July 2019 

Gloucestershire is one of the most geologically diverse counties in Britain. The aim of this field-based course is to take you towards an understanding of local scenery.  We will look at the components - the highly diverse  rocks and their structure; and processes - weathering, slope forming and erosion - which have combined to produce this equally varied landscape - the materials from which the scenery has been sculpted and the processes that have acted upon them since the area emerged from the sea 65 million years ago (about the same time that the dinosaurs became extinct) No special equipment is necessary, apart from stout footwear and possibly waterproofs - although we will hopefully have six balmy summer evenings! Meetings are held on Tuesdays each week, (apart from breaks on Tuesday 4th and 11th June), meeting at 7.00 pm and finishing 
at 9.00 pm or later (whenever the party feels in need of refreshment !!) at the following meeting points (see over) 

Cost: £50 for 6 week course 
or £10 per session 
For further details see over or telephone 
Dave Green on 01594 860858 


28th May - Stinchcombe Hill

The most westerly point on the Cotswold escarpment, and possibly the most visible and easily recognised. The escarpment is formed from flat lying sedimentary rocks starting at the top with the often fossil-rich Middle Jurassic limestones (approx 170 million years old), which overlie weaker sands and mudstones forming the middle slopes. The harder Marlstone forms the famous platform on which the towns of Dursley and Wotton are built, underlain by more mudstones forming the Severn Vale, producing a step-like landscape. 
Meet at the car park on the left, beyond the entrance to the golf course GR SO 744 983 

NOTE BREAK OF TWO WEEKS HERE – no meetings on 4th and 11th June 


18th June Sandhurst and Wainlode 
The River Severn has eroded its course maily along the outcrop of the soft Triassic Mercia Mudstone or the Jurassic Lower Lias Clay. In between these formations is a thin series of beds of more resistant rock – the Rhaetic, which forms a series of low wooded ridges broken by faults, and occasionally cut into by the river (as at Aust, Sedbury, Westbury and here at Wainlode) to form impressive cliffs. This location is also a classic area to observe the Severn Terraces. Meet initially at the car park (along the lane) of the pub The Red Lion, at the foot of Wainlode Hill (SO848259), from where we will travel in a few cars to Sandhurst for a linear walk of about 3km with a climb of about 60m.


25th June Bixslade and Bixhead 
Bixslade is a steep valley cut into the steep dip slope of the Upper Carboniferous Pennant Sandstone to the west of Cannop Pond> For hundreds of years used as a building stone, there used to be a tramway down from the main quarry at Bixhead to the stone cutting works at Cannop; a tramway that was also used to transport coal, and iron ore from deposits within the Pennant, that were worked within Bixslade. We will traverse the route of the tramway and return on a circular route involving a walk of about 3-4km and a climb and descent of about 130m. 
Meet in the layby (old section of road), on B 4234 north of Parkend, near the Stone Cutting Works, Cannop, at SO 615 095 


2nd  July Glasshouse 
A complex area of geology, where relatively ancient Silurian, Devonian and Carboniferous rocks meet younger Triassic sediments along the Malvern fault system. The older rocks have been thrown into a series of folds, whose north-south trend is faithfully reflected in the landscape by the outcrop of relatively resistant and weak rock, forming ridges and valleys They have also been cut by a major fault (the Glasshouse Fault), bringing older rocks (Lower Silurian) in the core of the May Hill anticline next to them, with consequent effect on the scenery.  This fault is an example of a strike slip fault, with mainly horizontal movement taking place; a little similar to the present San Andreas Fault in California. Meet at the roadside downhill from the Glasshouse Inn (used as the car park for the pub) SO709214. We will look at the geology by means of a circular walk of about 
3km with a climb of about 40m. 


9th July The Avon Gorge 
Possibly the most famous landscape in our area, but one whose origin is still the subject of hot debate! Why does the River Avon cut through the hard Carboniferous and Upper Old Red Sandstone ridge forming hills like Clifton Down, and the steep sides of the gorge, when it could easily have reached the Severn either to the north (via Bradley Stoke) or south (via Nailsea) of Bristol? Why are the Downs so flat? 
Meet at the car park in the old quarry on the eastern (away from river) side of the A4 Portway below Clifton Down. ST 561 740, from where we will ascend a footpath “The Gully” to Durdham Down to gain a view and walk along towards the suspension bridge before returning to the car park


16th July : Kempley and the Mystery Valley(s) 
The southernmost extremity of the Woolhope Dome lies just SW of the village of Kempley. The folded and heavily faulted marine Silurian rocks here form distinctive scenery in themselves, but the landscape is dissected by deep, steep-sided valleys, discordant to the underlying geology, some of them lacking any sign of the stream that must have eroded them. We will examine the geology and scenery of this beautiful area by means of a circular walk of between 4 and 5 km, along footpaths (some stiles involved) and quiet country roads over relatively gently undulating countryside. 
Meet at the large lay-by (SO672 295),  200 metres south of Kempley Church.


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