6oz. fluorescein appeared from Pwll Byfre after 48 hrs (Harvey, 1948); 8oz.appeared in Hush Sum in 18 hrs 9Baynton, 1963) Live feed of rainfall at Penwyllt and Water level at the step Waterfall Series

L:59000
V:313

Ogof Ffynnon Ddu 1, OFD 1


NGR: SN 84790 15198
202 m.asl

Powys , Northern Outcrop - Central (Penwyllt to Penderyn)
 map using leaflet map:
Active Cave
Access This is one of the 3 entrances to Ogof Ffynnon Ddu. The cave is in a Nature Reserve and Access is controlled. See caving.wales for current Access arrangements
Description OFD 1 Entrance is not the original entrance to OFD, but a slightly newer one dug to bring the entrance on what was Cyril Powell's land. OFD is the deepest (from an aven in OFD 3 to FD) cave in Britain and the third longest, and ranks amongst the longest caves in the world. The cave comprises of a complex system of large and small fossil passages, finely decorated in places and a fine and very long streamway. It is divided into four distinct sections : OFD 1, Cwm Dwr, OFD 2 and OFD 3 The length of OFD 1 is around 6000 metres. A complex series of passages in the entrance lead to an active passage from which at various points further passages can be reached. The stream is liable to flood. Divers proved the connection to OFD 2 in 1966 and to Cwm Dwr in 1967 and Top Entrance was dug open in 1967.
History Original entrance, SWCC 1946; Current entrance dug to be on Cyril Powell's land; OFD 2 - 1966 by Divers; OFD 3 - 1966 SWCC
Hydrology 6oz. fluorescein appeared from Pwll Byfre after 48 hrs (Harvey, 1948); 8oz.appeared in Hush Sum in 18 hrs 9Baynton, 1963) Live feed of rainfall at Penwyllt and
Conservation SSSI: 0099 Ogof Ffynnon Ddu (Mixed) GCR: 553 Biological records
Gallery

P.Binns/BCRA
1949

2006
Brendan Marris
2010
Gary Evans
2020
Survey
C.L.Railton 1953
Welsh Geological Quarterly, 1(2) p.36
London UCC Jnl 5
SWCC 1969
Nyth Bran Series, SSS 1984
SWCC 1994
Descent 135 [OFD I-II sumps]
SWCC 2014 resurveyed, redrawn, coloured
Josh Bratchley, Dip Sump CDG nl.208/SWCC Newsletter 136, p.33
Josh Bratchley, Main Stream Sump CDG nl.208/SWCC Newsletter 136, p.34
References
Yorkshire Ramblers Club Journal 7 (23) 1938 pp.52-61 Early description
British Caver 3 1938, 81-86 Report on original exploration of Cwm Dwr and survey
Cave Diving Group Newsletter 5, 1-13, 1946
CDG Report (1/46), 1946. Diving at the Rising
British Caver 15 1946, 37-39 & 43
British Caver 15 1946, 80-87 Early exploration and Survey
British Caver 15 1946, 99 Early exploration
British Caver 16 1947, 52-55 Diving
British Caver 16 1947, 56
British Caver 16 1947, 76-77 Discovery of Human Skeleton
British Caver 16 1947, 78-81 Discovery
British Caver 16 1947, 88-91
British Caver 17 1947, 95-103
CDG Report (5/46), 1947. Diving opportunity at the rising
British Caver 18 1948, 88-90
CRG Transactions 1, 13-20, 1948. Cave formation and survey
CRG Newsletter 15, 2-4, 1948. Water tracing from Pwll Byfre
CRG Newsletter 16, 4-5, 1948. Geology
CRG Newsletter 22, 5-6, 1949. Air beneath calcite gours
CRG Transactions 1 (1), 1-47, 1950. Cave formation and survey
SWCC Newsletter, Jun 1950, forcing the end of Low's passage to discover RAWL Series [Railton, Afford, Wild, Little]
CRG Newsletter 35, 15-16, 1951. Observations on being trapped
Cullingford, C.H.D. (1951) Exploring Caves,pp.75-77
British Caver 22 1951, 16-17 Preservation of fauna and flora
British Caver 22 1951, 68-69
British Caver 22 1951, 70-75 Rescue
British Caver 22 1951, 76-78
British Caver 22 1951, 91-95 Rescue
British Caver 25 1951, 84-5 Access
Cave Science 3 (18), 107-8 1951. Rescue
BOC Bulletin 2 (12), 80-85, 1951. Rescue
HCC Newsletter 2, 7-8, 1951
Wessex Cave Club Circular 2 (30), 4-6, 1951. Rescue
SWCC Newsletter , 1951. Discovery of Escape Route
CRG Newsletter 40, 4-6, 1952. E.A.Glennie, The Effect of Submerged Areas on Water Tracing Tests [Pwll Byfre to OFD]
CRG Newsletter 41, 4-5, 1952. E.A.Glennie, Hydrology
CRG Transactions 2 (2), 135-48, 1952. Description and discussion on significant air currents.
SWCC Newsletter 6, 1953. Ascent of Bat Aven. Grade 2 Survey
SWCC Newsletter 6, 1953. Discussion of many digs in boulder chamber
WSG Bulletin 23, 2, 1953. Access
Britain Underground, 1953
SWCC Newsletter 7, 1954. Connection with Pant Canol
SWCC Newsletter , 1954. Access
Casteret, Norbert, The Darkness Under the Earth, pp.109-110, (1954) [1951 rescue of Railton and Little]
CRG Pub. No.6 Ogof Ffynnon Ddu. C.L. Railton.
CRG Newsletter 48, 13-14, 1954. C.L. Railton, Climbs and descents in Ogof Ffynnon Ddu
SWCC Newsletter 13, 1955. Note on start of dig at Cwm Dwr
SWCC Newsletter 16, 1956. Electromagnetic Survey
Wessex Cave Club Journal 4 (57), 85-86, 1956. Access
SWCC Newsletter 19, 8, 1957. Extension to Rawl Series
SWCC Newsletter 20, 1-4, 1957. Investigation of airborne bacteria
SWCC Newsletter 20, 4-5, 1957. Mud Sump
SWCC Newsletter 21, 8, 1957. Whiskey Aven connection to R-W Series
SWCC Newsletter 21, 3-7, 1957. History of early exploration and survey of Cwm Dwr
SWCC Newsletter 23, 2-5, 1958. Discovery and description of extension with Grade 4 Survey
SWCC Newsletter 23, 5-6, 1958. Digging on Boulder Series
SWCC Newsletter 24, 17-19, 1958. Rescue
SWCC Newsletter 24, 20, 1958. Medical note on rescue
SWCC Newsletter 26, 3-6, 1959. Discovery of Coronation Aven Extension
SWCC Newsletter 29, 7-9, 1959. Description of 3 dives
SWCC Newsletter 33, 17-20, 1960. Details leading to rediscovery of Cwm Dwr
SWCC Newsletter 34, 20-21, 1960. Boulder fall at entrance to Rawl series
SWCC Newsletter 34, 7-11, 1960. Discovery, divers find a stream
SWCC Newsletter 34, 12-14, 1960. Discovery of small extension & survey of Cwm Dwr
SWCC Newsletter 35, 3-5, 1961. Diving in boulder series
SWCC Newsletter 35, 18-22, 1961. Likely places to dig for way on in Cwm Dwr
SWCC Newsletter 37, 9, 1961. Wireless contact in boulder series.
CDG Review 1961 Diving
SWCC Newsletter 40, pp.11-13, 1962. W.H.Little, The Fault Series
SWCC Newsletter 40, pp.14-20, 1962. P.I.W.Harvey, The origins of the O.F.D. cave system
SWCC Newsletter 40, pp.20-21, 1962. Rane L.Curl, Siedyn(s) in OFD [calcite/aragonite precipitation experiment]
Caves in Wales and the Marches (Dalesman), Jenkins, D.W. & Williams, A.M., 1st Ed.1963, p.35, 26
Welsh Geological Quarterly, 1(2) pp.37-38, (1965), R.A.Stevens,Ogof Ffynnon Ddu
SWCC Newsletter 51, 1965, p.9. Water tracing carried out in Wales.
The Speleologist 2 (10), pp.10-11, 1967. Charles George, The recent find in Ogof Ffynnon Ddu
London Universities Caving Clubs Journal 5, 1968, Ogof Fynnon Ddu 2
O'Reilly, P.M.,O'Reilly, S.E.,Fairburn, C.M., SWCC, Ogof Ffynnon Ddu, (1969)
SVCC Jnl 3 pp.33-35,1970, R.Lewis, An Extension to Ogof Ffynnon Ddu Three
BCRA Transactions 1(2), pp.65-73, 1974, PM O'Reilly & LG Bray, A preliminary hydrological study in Ogof Ffynnon Ddu, Breconshire
BCRA Transactions 1(2), pp.75-84, 1974, LG Bray & PM O'Reilly, Preliminary oxidation studies on some waters from the Ogof Ffynnon Ddu System, Breconshire
BCRA Transactions 2(3), pp.127-132, 1975, LG Bray, Recent chemical work in the Ogof Ffynnon Ddu System: further oxidation studies
SWCC nl.85, pp.1-6, 1975. P.L.Smart & R.Smith, Water tracing in Ogof Ffynnon Ddu [Cwm Dwr catchment]
Nature in Wales NS.2(1/2) 1983, R.J.Haycock, pp.34-41, Ogof Ffynnon Ddu NNR, Powys
Limestones and Caves of Wales, 1989
Caves and Caving, Summer 1993, p.6, Nig Rogers, Ogof Ffynnon Ddu 1 1/2 [Easter Series, Falcon Aven], in Bill Gascoine, South Wales News
Caves of South Wales, Stratford, T., 1995
Descent 135, pp.20-22, 1995, Steve Thomas, Follow that FROG!
Gazetteer of Human Remains in Caves
Selected Caves of Britain and Ireland, 1997
CSS nl 42 (8/9), p.92, 2000, Stuart France, OFD Resurgence Depth and Temperature Variation
CSS nl 42 (8/9), p.102, 2000, Stuart France, How fast does OFD flood? [can be within 2 to 4 hours of rain]
Cave and Karst Science 27 (3), pp.101-108, 2000, Clark R.L.Friend , Contribution of airflow to the control of seasonal variations in radon concentration in Ogof Ffynnon Ddu, Penwyllt, South Wales
CSS nl 43 (5), p., 2001, Stuart France, Comparative flooding rates for DYO and OFD [OFD rises earlier and drops faster]
CSS nl 43 (6), p.64, 2001, Stuart France, Comparative flooding rates for DYO and OFD (graph corrected) [OFD rises earlier and drops faster]
Cave and Karst Science 31 (2), pp.63-76, 2004, G.T.(Jeff) Jefferson, Phil Chapman. Julian Carter and Graham Proudlove, The invertebrate fauna of the Ogof Ffynnon Ddu cave system, Powys. South Wales, UK
Peter I.W.Harvey 2009 The Discovery and Exploration of Ogof Ffynnon Ddu in 1946
Peter I.W.Harvey 2009 Into Ogof Ffynnon Ddu II
Descent 220 p.10, Martin Groves, The Extra Mile [in OFD 3]
Descent 222 p.11, Richard Frost, Pushing OFD 3
CDG nl.208, Josh Bratchley, Main Stream Sump and Dip Sump
SWCC Newsletter 136, pp.31-34, 2019. Bob Hall, Recent Diving Developments in Ogof Ffynnon Ddu 1.
Brendan Marris Caves of South Wales
BGS Archives: BCRA/201W/B/25, 1942-1946
Descent 278 pp.24-27, Chris Jones, Gaining depth through Megzit
Catalogue of Speleological Sites...between...A4067...Pant Mawr Moor, Gary Evans (2021),p.140
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Cambrian Cave Registry entry 304
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