BATH GEOLOGICAL SOCIETY
FIELD TRIPS & VISITS 2010

Further details from the Field Trips Secretary
admin@bathgeolsoc.org.uk (01249) 813628 or 443019

Further details of the trips in March, May, June and July and updates to the programme as needed, will be made available at meetings and on this website.


January March May July August September November

Sunday 30th January

Brown’s Folly Nature Reserve

Elizabeth Devon

This is our annual clear-up of the Geological sites on this SSSI reserve. Come along with gardening tools or just take the opportunity to visit the sites and talk about geology.

Meet at 10.00 a.m. at Brown's Folly Car Park (G.R. ST 798663). Strong boots, waterproofs, hard hats are required.


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Saturday 27th March

Field excursion to the Mendip Hills at Charterhouse and Burrington Combe

Leader: Dr. Peter Hardy, former Senior Lecturer in Dept. of Earth Sciences at the University of Bristol

At Charterhouse we shall observe the relationship between the land-forms and the geology, especially the three main rock types, i.e. Devonian clastic sediments, Lower Carboniferous shales and limestones. The additional feature which is well seen here is the site of extraction of lead ore over the past two millennia, dating back at least to the Roman occupation of Britain, and the more recent evidence for local smelting of lead from the mineral veins.

At Burrington we shall examine in greater detail the lithologies and fossil content of the above-mentioned sediments, especially those of the limestones, but also a little of the shales. Loose specimens of the Devonian sandstone are also present in the lowest parts of the combe, and in addition we shall see sedimentary deposits from the Palaeozoic/Mesozoic transition of the Triassic sequence, represented here by coarse conglomerates which rest on an early valley floor formed when the combe was a desert wadi on the slopes of the newly elevated hills.

Suggested maps and reading - The best local topographic map would possibly be the O.S. 1:25,000 Explorer series ‘Mendip Hills West’, although there is now the very useful B.G.S. guide ‘Western Mendip’ which includes a really clear geological map at the same scale with more detailed inserts for Burrington and elsewhere, and could easily be used for grid. refs. This would make a very useful purchase as it includes a detailed explanatory booklet about the geology and local history.
In order to better appreciate the detailed lithologies a hand-lens would be of great use.

Car parking - The public car-parking area/s at Charterhouse include an off-road area with parking for six to eight normal sized vehicles at ST 505 556 and on the public roadside room for around a dozen vehicles at ST 503 555. If both of these are full there is car-parking in off-road space for several vehicles at St. Hugh’s church at ST 502 557. Suggested driving time from Bath centre around 1 hour.
Field trip assembly point is at the roadside at the stile into Ubley Warren, ST 504 554 at 10.30 a.m. The walking distance in the morning will be around one mile at a gentle pace over reasonably level ground, mostly on paths, with minor climbs of about 20-30 metres, some rocky ground, but mainly smooth grassy areas and gravel. There are no public facilities at all at Charterhouse, although there is a field study centre nearby (ST 503 557).
The morning will conclude at lunch-time, around 1.00 p.m. and the next venue is at Burrington Combe, to which cars could drive for lunch and toilets, both public and private (in the café) are available. The afternoon session will start from the roadside at the public toilets ST 477 587 and will begin at 2.00 pm unless adverse weather alters plans. There is usually adequate parking somewhere in the lower stretch of the combe, but if not nearby it may be necessary to walk up from a large area around 200 metres to the north on the roadside, formerly used by the now defunct garden centre. Otherwise there is quite a lot of roadside parking a little further up the combe, again a few hundred metres away. The afternoon session will involve some half mile of roadside walking, and optional extra few hundred metres off-road along (through!) a shallow stream, where waterproof boots would be advantageous. There is a moderate climb throughout the outward leg of this walk, maybe 100 metres in all.
The walks will offer little shelter, especially if windy, so bring warm and waterproof clothing and stout footwear is essential. Wellington boots are a suitable alternative for the afternoon session, but strong gripping soles better in the morning, when the ground should be fairly dry, but the grass is often slippery. Hard hats are always a good idea, although there is no need to expose oneself to immediate hazards from falling rock. Hammering of rocks is to be avoided, these are protected sites and loose material is plentiful.



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Saturday 1st May

Tintern Quarry

Leader: David Owen, Head of Geology, Gloucestershire Geology Trust

Sorry - the leader is not available. The Field Secretary will be at the site to assist self-led visitors

Tintern Quarry exposes the thickest section of Carboniferous Limestone in the area. The quarry face itself is some 400 ft high, with several benches and haul roads. In the base of the quarry is the Lower Dolomite which has some good dolomite crystals in it. A forestry track circling the quarry provides safe and easy access to a full sequence from Lower Dolomite, through Crease Limestone, Whitehead Limestone, Lower Drybrook Sandstone, Drybrook Limestone and Upper Drybrook Sandstone.

The junction between Lower Dolomite and Crease Limestone is uncertain in this area as dolomitisation has affected both units to a high degree. The Whitehead Limestone is variably porcelaneous, mudflake breccia and dolomitic mudstone, with many stromatolites and a significant palaeosol at the top. Lower Drybrook Sandstone is a coarse gritty sandstone but there are some curious features exposed in the track cutting that the leader will invite suggestions about. Drybrook Limestone is partly oolitic, partly porcelaneous and has palaeokarst within it (nearby is an area of limestone pavement which we could visit if we have time).

Meet at 10.30 am at Tintern Quarry (SO 550 984)
Please wear stout walking shoes and suitable outdoor clothing.
Bring your own packed lunch.



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Saturday 3rd July

Watchet and District

Leader: Prof Eric Robinson

During the day we shall be looking at the building stones of Watchet and exploring the fossiliferous Lias at Helwell Bay. We shall also investigate the beach and river at Doniford and study the gravel cliff in this bay, which has yielded the remains of stone age man and mammoth.

Meet at 11.00 at the car park in Harbour Road, Watchet. Packed lunches, waterproof gear, hard hats and strong boots are required.



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Saturday 4th September

The Severn Valley Railway Landscape and Geology Trail

Leader: Elizabeth Devon

If you have not yet booked and paid at the group rate, please download and complete the Booking Form

This trail runs from Kidderminster to Bridgnorth. Steaming through geological time on the Severn Valley Railway. In the comfort of a railway carriage, you will encounter landscapes created in hot, dry deserts, steamy tropical swamps and exceedingly cold Ice Age conditions. You will see how the underlying rocks and the erosive effects of the river have influenced the landscape.

The plan is to arrive at Kidderminster to catch the 10:25 train which arrives at Bridgnorth at 11:34. After a leisurely lunch and maybe a stroll around the town we will return on the 14:45 arriving back at Kidderminster at 15: 52.
We need a party of 15 or more adults to qualify for a group discount on this trip (£12.95 instead of £15.50 for adults).



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November

Annual Reunion of the Geologists’ Association

For details, see www.geologists.org.uk


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