field notes 2017Posted by Vince Simmonds Sun, October 22, 2017 16:05:14
Green Swallet [NGR ST 5506 4771] is something for the connoisseur. A couple of
short drops lead to low crawling-size passages with an ample supply of mud, much
like caving in liquid cement, there are some tight squeezes to negotiate along
the way too. It is, however, probably the longest known cave in the world in
Blue Lias Limestone and there are some fine selenite crystals to be seen.
dug by persons unknown in the 1930s and by Wessex Cave Club in 1961. A new
phase of excavation began in 1979, continuing to 1989 when the first
breakthrough was made.
October 1992, there was a period of sustained effort by myself, Graham ‘Jake’
Johnson, Rich Blake and Tony ‘J’Rat’ Jarratt, occasionally aided by others, to
‘push’ the current end of the cave. Eventually, there was a tantalising glimpse
into ‘black’ space beyond, it looked good and we were excited.
my personal logbooks:
28/10/1992 with Jake and J’Rat
night’s bang cleared some stuff, one quite large boulder. I still couldn’t
squeeze through, but did get a better look and it does look good, nice strong
draught and what looks to be, hands and knees size passage going away, can only
see 8 – 10 feet. Jake was in raptures when he came back from drilling and
charging. We also shifted all the spoil back to the aven. J’Rat, also cordoned
off some fine selenite crystals. Another 1.5 hours trip.
29/10/1992 with Jake and Murray Knapp
some hammering, chiselling and barring, I finally managed to squeeze through
into new passage, 15ft. x 15ft. x 3ft, high. Waited for Jake and Murray to pass
through and then exploring brand new cave.
the squeeze, you enter a bedding plane and then, a T Junction, the right-hand
leg closes-down after 15ft., to the left, hands and knees crawling, up to 6ft.
wide and very well decorated, leading for about 40ft. to another T Junction.
The left-hand side leads for about 40ft.of crawling, with stal and selenite, to
a blind chamber, 10ft. x 5ft. x 3ft., with a dripping crack and nice float
calcite on the edge of a pool. The right-hand leg [of the T Junction] goes for
about 40ft.to a left turn and then, 15ft. to boulder break-down, some shoring
and a bit of work here will lead to another breakthrough next trip. This small
passage has the largest selenite crystals I’ve ever seen and some very nice
stal and rusticles.
entry squeeze is going to be left awkward because the whole area contains some
very delicate formations. It also makes all the work worthwhile.
30/10/1992 with Jake, J’Rat and Rich
for more discoveries!
take too long to get to the break-down, this time we had some short scaffold
poles for a bit of shoring-up. Jake soon removed, what appeared to be a
chock-stone, and then squeezed through into more spacious open passage. The
way-on continued for about 60ft. until reaching more, big block break-down,
Rich managed to get in a further 15ft. to a dig, very squalid as well, so
that’s about it for a while.
new section doesn’t have any stal but, it does have some large selenite
the breakthrough, several surveying trips were made with Trevor Hughes, the new
extension survey length was 76 metres, we had guesstimated it as 230ft.(70m),
so we were quite close. While we were at it, the entire cave was surveyed.
November, again on a Wednesday evening.
Vince, Jake and myself surveyed 97m of passage that evening. The Compost
Corner legs were most remembered - Vince managed, most successfully, to ensure
that for virtually every survey station, to read the compass, I had to bung my
somewhat hirsute chin into the mud, revenge I suppose for making him do all the
outward trip backwards.” (Hughes, 1998).
V.J. Personal logbook 1990 to 1992
A., Taviner, R. and Witcombe, R. 2015. Mendip Underground: A Cavers Guide (5th
Edition). Mendip Cave Registry & Archive
T. 1998. Welsh’s Green Swallet – the Survey (Or The Mud-Pile Strikes Back) in Belfry Bulletin, 495 p22-25. February 1998
field notes 2017Posted by Vince Simmonds Thu, October 12, 2017 06:28:0011th October 2017:
Attended a meeting of the Somerset Geology Group (SGG) hosted at the Earth Science Centre, Stoke St. Michael.
The meeting discussed future plans and structure of the SGG followed by an open meeting to outline survey forms and procedure. The talking was followed by a practical field session at Tedbury Camp, a Mendip geo-classic.
Jurassic Inferior Oolite overlies Mid-Carboniferous Clifton Down Limestone (CDL), Lithostrotion, a colonial coral, is a type fossil to identify CDL. Peter Hardy described the unconformity in some detail, pointing-out some significant features. The holes left by boring bivalves (and other creatures) in the eroded Carb. limestone 'hard ground' surface have been filled by Jurassic sediments, these particular geological features have become difficult to see.
A Neptunian dyke, also filled with Jurassic sediments, there are hard ground surfaces in the Jurassic deposits too.
Unfortunately, the exposures are suffering from some unnecessary attention, as at the De La Beche Unconformity nearby.
Other features, such as fault induced folding and chert formation were discussed. The geological importance of Tedbury Camp, not just as a local/regional asset but as a wider national, even international resource was stressed.
We even got around to talk about the survey forms, eventually. An enjoyable field trip.
field notes 2017Posted by Vince Simmonds Fri, September 22, 2017 05:43:1421st September 2017:
Back in the day, there may have been more of us, but many of the team fell by the wayside, just me and Tav made the journey.
Along the route, up through Chamber 20 to the dig, there is plenty of evidence for some recent high-energy water flow, many of the mud banks have been washed-out. The water appears to have issued from above, so fast surface run-off likely, it has been rather wet recently. Maybe there's a higher network of passages.
We were not surprised to arrive at the dig and find it underwater. Spent a bit of time tidying away the tools and other equipment, before making our way back out of the cave, taking some stuff out with us. It is still a warm trip, even when a gentle pace, taking time to look around.
field notes 2017Posted by Vince Simmonds Mon, September 18, 2017 06:49:53
Of wood and stone. The use of wood and stone in the construction of prehistoric megalithic monuments has been interpreted by some as, wood representing the living, life, whereas, stone is suggested to be, the dead, death. Wooden circles are replaced by stone, for example, as at Stanton Drew.
field notes 2017Posted by Vince Simmonds Mon, August 14, 2017 06:15:1612th - 13th August:
Above: Worm's Head, looks like a dragon swimming out to sea!
Spent the weekend helping out with exploration of a cave near Port Eynon, but on Saturday evening, I went for a walk along Rhossili Bay.
Shipwrecks and sea caves!
There were boulders of fantastic breccia with some massive clasts and a matrix of red sand with calcite veins and shell fragments. I assume, also a carbonate cement.
Scale = 8cm.
field notes 2017Posted by Vince Simmonds Mon, August 07, 2017 06:30:235th August 2017:
Duncan Price visited Wookey Hole yesterday and reports that, after recent rain, the dig has flooded again.
field notes 2017Posted by Vince Simmonds Sun, July 23, 2017 15:22:0023rd July:
Sunday morning stroll through Harptree Combe. This time of year it is very lush and green. There were a few showers of rain.
Somebody has spent a constructive hour or so making these dead wood sculptures in the stream.
Passing the ruins of this building by the stream.
The dead heart of an ash tree, snapped off in the recent storms.
Tree graffiti, initials carved into a beech tree. I wonder who 'KC' might be, not sure who else is involved?
Islands in the stream. There are plenty of these fantastic little vegetation covered cobbles and boulders in the bed of the Molly Brook.
field notes 2017Posted by Vince Simmonds Fri, July 14, 2017 06:20:29
13th July 2017: with Jake, Tav and Nick, back from his travels, just!
Continued with the slope engineering, progress is being made. Nick and Tav took-up the digging duties, I was on hauling, Jake, also hauling, but attended to spoil dispersal as well. We will get back to digging at the bottom soon.
field notes 2017Posted by Vince Simmonds Fri, July 07, 2017 06:29:506th July:
with Jake, Jonathon, Tav, and that stalwart of the Grampian, Goon.
The usual warm trip up to the dig, the difference was the trail of blood left by Goon.
At the end, Jake and Jonathon, quickly got on with the digging, continuing to engineer the slope. Tav and I were on hauling duty and occasionally re-arranging some lumpy pieces of limestone, Goon was assigned to spoil dispersal. A good steady session.
I will need to bring the capping kit next session to split a few hefty boulders.
To the Hunter's Lodge Inn to quaff a few glasses of fine ale.
field notes 2017Posted by Vince Simmonds Fri, June 16, 2017 06:33:5215th June 2017:
Jake, Tav, Duncan P, Pete Bolt and Max Fisher.
Continuation of the slope engineering. Tav, Pete and Max with a combined effort in spoil removal, Duncan and me were hauling it away.
Jake was in control of spoil dispersal management. And, building a retaining wall.
Another fine evening in this mellow spot.
field notes 2017Posted by Vince Simmonds Fri, June 09, 2017 11:17:13BCRA 2017 Field Meeting:
Caves and Karst of the Gower Peninsula, Wales.
19-21 May 2017. A personal account.The Salt House, Port Eynon.
Walk: Pilton Green (NGR SS 4465 8710) via Long Hole Cliff, along the coast path back to the campsite at Port Eynon. The aim of this excursion was to look at various unrecorded resurgences, and a number of archaeologically sensitive sites.
John Cooper talked about the caves, karst and the glacial moraine that seals much of the limestone in this locality. Paviland Cave was not visited due to adverse tides, but the water levels didn't look much different to when I visited the cave a few years ago.
It was a pleasant stroll along the coast path, stopping every now and then to admire the view and discuss the geological out-crops.Oxwich Head Limestone Formation
, described as thickly bedded, fine to coarse-grained, recrystallized, bioturbated, skeletal packstones with distinctive pale to dark grey mottling and pseudo-brecciation and ooidal limestones. Units of dark grey, irregularly bedded skeletal packstones with shaly partings are developed at intercals. Thin unitof calcareous sandstone and sandy skeletal packstone [Pant Mawr Sandstone Member and Honeycombed Sandstone Member] at the base in Vale of Glamorgan and north-west crop of South Wales Coalfield respectively. Unit of ooidal limestone in lower part [Pendyrn Oolite Member] on north-west crop of South Wales Coalfield. Palaeo-karstic surfaces, overlain by red and grey clay palaeosols, punctuate the formation; thin coals developed in Gower (BGS iGeology online).
High Tor Limestone Formation
, mid-grey, predominately thick bedded, fine to coarse-grained, burrowed, skeletal packstones with thin beds and partings of shaly dolomite mudstone and siltstone. Some thin-bedded, dark grey bituminous packstones interbedded with thin argillaceous wackestones and mudstones. Coarse, locally cross-bedded, peloidal/skeletal/oolitic packstones/grainstones developed in lower and upper parts in north sections. On south-east crop of the South Wales Coalfield the formation is predominately dolomitized (BGS iGeology online).
A detour from the path was made to visit Long Hole
, a c.20m long, phreatic tunnel. The cave once had a thick sloping flowstone floor, but this had been excavated c.1850 by antiquarians, in the search for animal bones. Evidence for the flowstone floor visible, in places, on the cave walls. The animal remains recovered were from the last interglacial and the last glacial periods.
From here some of us continued along the coast path to Port Eynon, the rest returning to Pilton Green. On the way, those of us on the coastal path, stopped to admire Culver Hole
, it has been blocked with stonework construction to create a dovecote, or so one of the stories go.Saturday.
Today's itinerary involved two excursions, the first was to the Bishopston Valley, beginning at Barland Quarry. Meeting at the car park (NGR SS 5785 8968).
The geological sequence: Bishopston Mudstone Formation overlies Hunt's Bay Oolite Sub-group, which in turn overlies High Tor Limestone.Barland Quarry Cave
, was exposed during quarrying operations. A narrow rift section, c.40m long and c.10m high, ends at a small stream and choked sump. There are several remnants of caves (Kittle Hill Caves
) that are likely to be connected to the quarry cave. From here, we followed the Creten Stream to where it disappears into Bishopston Sinks No's 1 & 2
, there are a succession of, currently, dry sinks further down the valley.
Along the way we stopped to look at the fine Daw Pit
, it is an impressive sight.
Relic caves in the valley possibly indicate that the valley floor was c.10m higher. Ogof Ci Coch
was excavated by Rob Dinnis in 2012, no archaeology was encountered. A short detour was made to Gulver Pit
, another fine sight, described as a "large rent in the hillside". Guzzle Hole
is accessible for c.50m to the first sump. Beyond the sump, some 400m of passage have been surveyed by divers. Near the bottom of the valley the water can be seen to emerge from several springs.
The second excursion of the day was to Coed y Parc (NGR SS 5393 8975) to visit Green Cwm and LLethryd Cwm. These cwm's together form a c.1.5km dry valley in the centre of an extensive area of faulting.
In Green Cwm evidence for Upper Palaeolithic, Mesolithic, Neolithic, Bronze Age and Roman presence has been found in the caves and cliffs. There is a Neolithic chambered tomb of Cotswold/Severn type, known as the Giants Grave.
It is interesting that the re-constructive work at Parc le Breos has similarities to that seen at Stoney Littleton, Wellow in Somerset, another Cotswold/Severn type.
Although Cat Hole Cave
has a gated entrance the group were permitted access. In the cave, the roof consists of a number of high fissures, narrowing at the top. The base of these fissures has been eroded away to form the main chamber of the cave.Lower Cat Hole Cave.
Further up the valley, is found Llethryd Swallet, where I managed to gain access through the, now exposed, flood sink and re-emerge from the gated entrance.
On the way back down the valley a brief stop at Tooth Cave
, the longest recorded cave on the Gower Peninsula with over 1500m of surveyed passages. It is also an archaeologically sensitive site, hence the now gated entrance.Sunday.
Started the day on Cefn Bryn, where I parked the van, and walked over to visit Maen Ceti (Arthur's Stone), an impressive burial chamber.
The large boulder that forms the capstone, is an erratic carried to the hill top by an ice-sheet, it originates from Mynydd Carrig, located 40 miles to the north.
From the top of Cefn Bryn the topography of all of the area surrounding the next venue, Stout Hall can be seen. The underlying Old Red Sandstone rises on three sides to form a basin of limestone which was once filled with ice. At the southern the dip is south-east leading towards the Oxwoch Bay syncline, here the lower limestones are overlain with Marros Group Formations. Much of the area is covered by glacial diamicton, with the Paviland Moraine forming the south-west horizon.
Stout Hall Cave, has an impressive entrance, tall, c.1m wide, entering a lofty chamber. Daylight enters from other higher entrances.
The cave has been modified, there are several shot-holes to be seen. It has also been used regularly, in more recent times, as a dump. Bottles, broken pottery, rusty iron and ash forms a talus in one section.
There is evidence of recent flooding, wooden pallets wedged in narrow fissures, and leaves adhere to the main chamber walls to a height c.2m above floor level.Members of the group look at the results of a photogrammetry session in the cave.
The photography impeded the chance to explore fully but several geologically interesting features were noted, like this death assemblage.
It would be interesting to investigate the sedimentology in the main chamber, and some of the side passages, although the fill is fine, and rather sticky.
In the surrounding woodland there is plenty of scope for further cave development, albeit most likely to be choked.
Later in the morning, went over to investigate the site of a palaeo-lake in an adjoining field. Several potential 'sink' features were noted, and I'm not going to get into the argument about whether they are sinks or something else. In the field, medieval field boundaries were clearly visible, these are seen on a LiDAR image of the site distributed with the field notes for the weekend.
Walking back to the car park, I pointed out another feature, a drainage ditch parallel to a stone-built boundary wall has been channelled into a 'sink'. There were several mature trees growing over the stone wall, and it is possible that some working of the rock outcrop surrounding the 'sink' had occurred in the past. Close-by was a depression with some evidence of recent slumping.
That was the end of the action for the weekend. A thoroughly enjoyable field meeting, and a return to the area is planned.
field notes 2017Posted by Vince Simmonds Fri, June 09, 2017 07:00:058th June 2017:
with Jake, Nick and Tav.
After some recent torrential rain, it was a relief to find that there wasn't any water running into the dig.
We had a brief discussion about how best to proceed, as the dig gets ever deeper. The decision was that we should engineer the slope before continuing downwards. Jake and I began to dismantle the upper retaining wall and remove the sediment behind it. The rocks were stacked to one-side, as they will be required later. Tav and Nick were carrying out the hauling and spoil dispersal. With two people filling the skip, they were sometimes, rather on the heavy side, as Tav's back will attest. There will be several more sessions needed before forward and/or downward progress can resume. Also, the engineering works will help to protect the dig from too much slumping should it get wet and flood in the winter.