Lectures and Excursions


The group holds meetings and talks at Hanson’s cement works near Clitheroe.

The dates and times of which will be posted on this page

Winter program 2018

16 November
Professor Steve Donovan – Naturalis, Leyden, Netherlands
He will speak about the geology of Jamaica

14 December
Joseph O’Neill, MSc – (date to be confirmed)
A talk on his recent visits to the Yukon in pursuit of gold and to Angola searching for diamonds.

28 December

Professor Steve Donovan will lead a field excursion at Cleveleys beach, meeting at 11 am

2019 Events

25 January 2019 
Lesley Collins
The Dalradian of N W Scotland

15 February
Annual General Meeting followed by PdS on the “Aspects of the geology of Bhutan”

23 February

Recce at the Syke’s anticline, Trough of Bowland

March 15

Harry Pinkerton (vulcanologist) will give a talk on “How Volcanoes Work”

31st March Healey Dell and Thurns Head

Leaders Peter Del Strother and Brian Jeffrey

MGA / GeoLancashire joint field excursion.
31st March 2019 – 10.00am at ‘Cowm Water Ski Centre’, off Tong Lane, Whitworth, OL12 8BE (modest parking fee)

 

Thurns Head quarry, Whitworth (near Bacup, Lancs.), water ski centre car park at SD882188 (leader Arthur Baldwin)
Thurns Head quarry is in Namurian sandstones with mudstones. Spectacular examples of the non-marine bivalve trace
fossil, Lockeia isp., are abundant. Escape shafts of this bivalve were not found on the recce, so the challenge for the day will
be to find an example. An exposure in an old quarry face contains loading structures about a metre across where, at the
time of deposition, incoming sand has deformed soft mud beneath.
There is plenty of evidence of the industrial history of the site. Part of the route is up an impressive inclined stone trackway
with setts in the centre and metre long flat stones for tracks either side. The long stones have grooves worn into them from
long use by quarrymen, perhaps using sleds to transport stone more than a hundred years ago.
The walking distance is about 3km over moorland paths. The stone trackway is potentially slippery in wet weather

 

Healey Dell Nature Reserve, car park at SD879164 (leader Ron Powell).
The River Spodden flows through Healey Dell nature reserve, in part through a narrow gorge with waterfalls. Ferns and
other damp and shade loving flora abound. There is abundant evidence of the early woollen industry, including a
waterwheel pit for a fulling mill. There are also the remains of a paving slab ‘stone rubbing mill’, used to smooth ripple
marked stone flags. An adit, likely the site of mediaeval siderite mining, can be seen in a mudrock cliff by the side of the
river. The reasons for the formation of siderite will be discussed.
Two faults, one at either end of the reserve, bring the older Upper Namurian, Rough Rock, into juxtaposition with the
younger Westphalian, Lower Coal Measures. The more southerly fault is visible in the gorge. In the river bed are nice
examples of potholes, formed when water born small pebbles and sediment swirl to erode flask shaped holes in the
bedrock. There is also a variety of sedimentary structures in the cliffs on the side of the gorge, where the Rough Rock is well
exposed.
The walking distance is up to about 4km, mostly on excellent tracks and paths. In one location the riverside path is rather
narrow and potentially slippery in the wet. For those who do not feel confident about it there is an alternative route. The
main route continues along the side of a leat to a mill lodge. The café and associated small visitor centre are not far from
the lodge. Return will be via the railway track over the gorge and thence to the carpark. For those who wish to visit the café
later in the day, there is parking available.

 

Friday 5th April Hanson Cement Works

Prior a talk given by Peter Del Strother regarding the history of cement  there will be an opportunity to visit the quarry where the limestone is extracted.

The quarry visit will take place at 6pm and by 7pm the group will return to listen to Peter’s talk.

Details to follow

 

Tues 9th April:       Brinscall Quarry / Horwich Stone works

Due to a shortage of the original stone, this quarry is now providing stone for the building of the  Sagrada Família Cathedral in Barcelona. Some of this stone is being carved at the Horwich works before shipping. Visit details to follow.

 

Thursday 2nd May    Ecton Copper Mines

These mines in the Manifold Valley have been worked from Bronze Age times and are estimated to have produced  100,000 tonnes of ore. We will be hosted by geologists from Ecton Hill Field Studies Association  https://www.ectonhillfsa.org.uk/index.html

and the trip will involve  a talk on local geology/ mineralisation, a trip around to see surface geology/industrial archaeology and an underground visit.  Visit details to follow. (There will be a £10 per person charge for this excursion)

27 June Brymbo/Llay (MGA trip)

Leader Peter Del Strother

 

Leader: Tim Astrop PhD of Brymbo Heritage Project
For directions – see http://www.brymboheritage.co.uk/find-us/

At Brymbo are the in situ remains of a Pennsylvanian (Upper Carboniferous) ‘forest’, with both
lycophyte and calamite stems in growth position. Stands of Calamites stems are said to be very rare,
(Appleton et al. 2011. The Brymbo Fossil forest).
The base of the exposure contains plant stems up to about half a metre
in diameter in mudstone.
Stems over 1.5m diameter have been observed. Channels cutting through the mudstone can be
observed in a vertical face. Above this is a horizon with siderite nodules and at the top a coal seam of
Westphalian B age.

 

Channel infill

In September 2017 the Brymbo Heritage Project secured funding of £0.84M from the Heritage
Lottery Fund and is working to secure more to make the site accessible and to cover the fossil plants
which weather rapidly as soon as they are exposed.

 

Very large Calamites stem

The site is associated with a historic iron ore processing complex which includes blast furnaces. The
large maintenance workshop building is currently being restored, with a grant of £1.1M from the BIG
Lottery, to provide a visitor centre.
The excursion will include the industrial archaeology in addition to the geology.
Tim, our guide, is a palaeobiologist.
Bring a packed lunch. It is planned to take lunch at the site as there are outdoor picnic tables.
Walking distance is short, about a kilometre if all the industrial archaeological sites are included.
Conditions underfoot are fairly good, but boots are recommended.

Llay coal mine tip, about 6 miles north west of Wrexham. Meet at 2.00pm
Address: Hanson Cement, Former Llay Main Tip, Llay Road, Llay, near Wrexham, LL12 0TL
Leader: Jason Parry – Quarry Manager, Hanson Cement Padeswood

The coal mine tip is being reworked by Hanson Cement as raw material for cement production. It is
located quite close to Brymbo. Apart from coal we should be able to find cobbles of sandstone
containing plant fossils.
You can read something about the mine at http://www.welshcoalmines.co.uk/North/LlayMain.htm   

Walking conditions are fairly good. Walking distance is less than a kilometre. This is an operationalquarry site, so wearing of boots, safety helmet and high visibility jacket or waistcoat is compulsory. If
it is dry it may be dusty and wearing of eye protection will be required.
Peter del Strother
If you have questions, please email secretary@geolancashire.org.uk   

 

Thursday 11 July Bashall Eaves Permo Triassic outlier

 

Leader Alan Harrison

This will be an evening trip starting from Bashall Eaves…..Limited local parking

Details to follow

Mon (morning) 22 July  Preesall Salt fields meet at Knott End car park 10 am

Leaders G. Williamson and Barbara Gordon

In 1872 a Barrow syndicate exploiting the Furness iron ore decided to try their luck in the Preesall area of Lancashire and at 300 ft. discovered rock salt (Halite) approx. 400 ft. thick.

The men were lodging at the Black Bull Inn Preesall and asked their landlady to boil, dissolve and filter it to provide the first sample of Preesall salt.

The first shaft was sunk 309 ft. deep (to rock head)  8 ft. in diameter and lined with brick 41/2 inches thick and brine was soon being pumped to the surface into a collection tank to be processed locally.

It soon became apparent that the brine needed handling by a much larger corporation and so after buying aseveral acres of marsh land on the Fleetwood side of the river Wyre the embryonic Fleetwood Alkali company was born with the brine being pumped directly through a pipeline across the river.

The Halite deposit is bounded by the Burn Naze fault to the West and the Preesall fault the the East and fresh water for flushing the salt was drawn from East of the Preesall fault but after a period of time it was decided to “win” the salt by also mining. The “rock salt” was carried in tubs by rail to a jetty in the river to waiting vessels and transported world wide, such was the recognition of its quality.

The Mineral train
Original track bed to take salt from the mines to waiting ships

It soon became apparent the seepage from the fresh water supply was dissolving the roof of one of the salt mines and so a decision was made to evacuate the workers and stop all rock salt mining. Only four years later the Mercia mudstone cap supporting the cavern roof collapsed and an area of approx. seven acres disappeared, taking farm equipment and buildings into the mine.

One of the large “flashes” due to brine removal causing the mudstone roof to collapse

The collapse features (flashes) are plugged by fallen rock and glacial debris and are fished by a local angling club who witnessed Perch having changed pigmentation to blue (apparently a reaction to the brine) slowly return to their natural colour as the brine sunk deeper than their natural swimming depth

There will be a lot more to see and discuss during this  half day excursion over mostly flat ground, starting and finishing at Knott End car park.  After lunch we can drive over to the Trough of Bowland (45 mins./1 hour) to look at the Sykes anticline which has hardly any walking at all.

Monday (afternoon) 22 July Sykes Quarries

Leader Peter Del Strother

Visit to Sykes Quarries SD628519, on the Trough Road.
Car parking is available circa 200m south of the quarries on the east side of the road. If this parking area is full there are a few other small parking areas within a few hundred metres or so, and a large area about 1km southeast towards Dunsop Bridge.
Safety. The two quarries have not been worked for many years and the faces are probably stable. Nevertheless, those wishing to approach quarry faces closely should wear safety helmets. Access to entrances of both quarries involves a couple of hundred metres walking along the single-track Trough Road. Traffic may be a hazard. Both quarries have gently inclined access tracks, once used by quarry vehicles. Quarry floors are uneven with tussocky grass. The west quarry has a short scree slope below the face. There are no stiles. Mobile phones may not function; on the recce mine didn’t. Because of uneven ground, walking boots or similar are the preferred footwear. Overall walking distance will be about a kilometre.
Permission to access the east quarry, Crag Wood, has to be obtained beforehand. The land is owned by UU and let to the farmer at Sykes Farm. GeoLancashire will arrange permission. Access to Bracken Hill Quarry, west of the road, is not restricted.

 

What there is to see:
Crag Wood Quarry is located on the northern limb of the Sykes Anticline. The limestone exposed is the Hetton Beck Limestone, of Chadian age. The approximately 30° north easterly dip levels out at the southern end of the exposure. Although historically described as the Sykes Anticline, the structure is properly described as a pericline, a domal structure, as can be seen on Geological Sheet 59 (Lancaster) and 67 (Garstang). There is a useful cross section on the Garstang sheet. Soft sediment slump structures/slide planes crop out in the quarry face; these predate the folding which is of Namurian age, associated with the Hercynian Orogeny (~290Ma). Within the limestones, colonies of Syringopora are abundant in all orientations. Silicification is common, giving rise to tabular chert and silicified limestone, which sometimes contains crinoid ossicles. Whether the source of the silica is biological, such as from sponge spicules, or from another source will be discussed. In Crag Wood quarry some joint surfaces are coated with baryte

      

 

 

 

 

 

 

 

Lead mining, probably on a small scale, was carried out on both sides of the road. It began in the C16th and was at its most intense from 1866 to 1871. Little remains except for an adit and small scree slopes with fragments of baryte, for instance. The mineral vein strikes ENE WSW. The terrace of houses known as Smelt Mill Cottages, about 1.5km towards Dunsop Bridge, strongly suggests local smelting but no evidence, of slag for instance, has ever been found.
Many of the features seen in Crag Wood Quarry can also be seen in Bracken Hill Quarry, where there is also a scree of what seems to be mine ‘gangue’ including specimens of baryte and, more rarely, galena.
By walking up the succession towards the summit of the Trough Road it is possible to find outcrops of mudstone (Worston Shales, Chadian to Holkerian) and, near the summit, Pendle Grit. We will not be visiting those locations because parking is limited and there is plenty to see in the limestone quarries.
It is likely to take about two hours to do justice to these two quarry localities, but people could leave at any time to suit themselves

Bibliography
Technical Report WA/87/46, Geology of the Trough of Bowland area (SO65 SW). Part of 1:50,000 Sheets 59 (Lancaster) and 67 (Garstang). R A HUGHES
R. L. Gawthorpe & H. Clemmey, 1985. Geometry of submarine slides in the Bowland Basin (Dinantian) and their relation to debris flows
F. Moseley, 1962. The structure of the south-western part of the Sykes Anticline, Bowland, West Yorkshire (as it was then!)
F. Moseley, 1961. Erosion surfaces in the Forest of Bowland.
N. Riley 1990. Stratigraphy of the Worston Shale Group (Dinantian), Craven Basin, north-west England.
Geology Sheet 67, Garstang and associated Memoir.
Geology Sheet 59, Lancaster and associated Memoir

https://www.bgs.ac.uk/downloads/start.cfm?id=1466

gives access to a free download of A lithostratigraphical framework for the Carboniferous successions of southern Great Britain’. This includes the successions in the Craven Basin.

Knaresborough 15th August

Leader Lesley Collins

Aim : To visit Knaresborough Gorge and examine the Permian strata and their uncomfortable relationship to
the underlying Carboniferous rocks.
Meet:  10.30 am at Knaresborough Castle viewpoint overlooking the Gorge, Grid ref SE 349568.
Car Parks: Pay and display car parks at Conyngham Hall park off A59, Grid Ref SE 345572, £4 for > 4 hours,
and Waterside off B6163, Grid Ref 348567, £1.20 all day

Duration:  10.30 am to 4 pm. Total walk length c. 4 miles.
The Route:  From the Castle, we will go down the steps to Waterside and along Abbey Road to St Roberts Cave
by Grimbalds Bridge. Return route along S bank of the Nidd, crossing back to N bank at Low Bridge.
The last 3 localities are just N. of High Bridge in Conyngham Park.
The route on the N. bank of the Nidd is along metalled roads, but on the S bank, it is a woodland path
with several steepish step sections so stout walking footwear is recommended

Facilites:  Toilets at entrance to Conyngham car park and along Waterside.
Several cafes, and ice cream opportunities, on Waterside.
Cafes, several Bakeries, Sainsburys Local in town centre, Public toilets in Kirkgate.
Note: No hammering permitted.
It is not proposed to visit Mother Shipton’s Cave.
Entrance fee is £10 per adult plus £2 per car for those who wish to visit after the field trip.
Maps:  OS Explorer 1:25 000 289 Leeds

References:  Yorkshire Rocks and Landscape, YGS field guide.
Further Details: Lesley Collins, email lclongashes@gmail.com
Mobile number 07946 358444

 

Lancaster building stone (date to be announced)

This will be a Geotrail test run

Details to follow