Ogof Hesp Alyn (

Welsh Welsh may refer to: Related to Wales * Welsh, referring or related to Wales * Welsh language, a Brittonic Celtic language spoken in Wales * Welsh people People * Welsh (surname) * Sometimes used as a synonym for the ancient Britons (Celtic peop ...

for: ''Dry Alyn Cave'') was discovered by North Wales Caving Club in 1973 in the Alyn Gorge near

Cilcain Cilcain is a village and community, near Mold in Flintshire, north-east Wales. The village has an industrial history and includes the Millennium Woods, a post office, a public house, a parish church, a primary school (Ysgol y Foel) and a village ...

Flintshire , settlement_type = County , image_skyline = , image_alt = , image_caption = , image_flag = , image_shield = Arms of Flint ...

Wales Wales ( cy, Cymru ) is a country that is part of the United Kingdom. It is bordered by England to the east, the Irish Sea to the north and west, the Celtic Sea to the south west and the Bristol Channel to the south. It had a population in ...

. Reaching the end of the cave is a serious commitment involving 24 pitches and the draining of two sumps. The proliferation of short, awkward and muddy pitches appear best suited to be tackled by wire ladders, but in the 1980s a team of divers from the Wessex Caving Club who passed the sumps, concluded that

single rope technique Single-rope technique (SRT) is a set of methods used to descend and ascend on the same single rope. Single-rope technique is used in caving, potholing, rock climbing, canyoning, roped access for building maintenance and by arborists for tree cli ...

was preferable, avoiding the need for excessive numbers of people to carry the equipment. A

perpetual siphon Perpetual, meaning "eternal", may refer to: Christianity * Perpetual curacy, a type of Christian priesthood in Anglicanism * Perpetual virginity of Mary, one of the four Marian dogmas in Catholicism Finance *Perpetual bond, a bond that pays ...

has since been used at the first sump which does a good job of keeping the water level relatively low, when working properly. A BCRA grade 5b survey of the cave exists that was created by North Wales Caving Club in two phases, in periods during the original 70s exploration, and further exploration beyond the sumps in the 80s. As well as the main passage that meanders through the cave there are several interesting detours including the Northeast Chambers, the Mousetrap series and the Wormway, which gets its name from the numerous worms that live in the sediment. Much of the cave is wet and muddy, with the entrance series setting the theme for what is to come later on. With more recent discoveries, the length of cave passage totals extending over a vertical range of about . The entrance would have functioned as a rising prior to the lowering of local water levels by mine drainage. As drainage only took place in the early 20th century, Ogof Hesp Alyn provides a valuable opportunity to study a cave system developed almost entirely by a

phreatic ''Phreatic'' is a term used in hydrology to refer to aquifers, in speleology to refer to cave passages, and in volcanology to refer to a type of volcanic eruption. Hydrology The term phreatic (the word originates from the Greek , meaning "well" ...

processes which remains largely unmodified by

vadose The vadose zone, also termed the unsaturated zone, is the part of Earth between the land surface and the top of the phreatic zone, the position at which the groundwater (the water in the soil's pores) is at atmospheric pressure ("vadose" is fr ...

streams. Despite the drainage that now occurs down to the Milwr Tunnel which is several hundred feet below, during periods of intense wet weather the cave can fill completely with water. This is quite rare but any visitor should take care. When the water level recedes, the 'Sand Crawl' can still remain a sump for weeks later. It lies close to another cave, Ogof Hen Ffynhonnau, which lies about further upstream in the Alyn Gorge. These two caves with

Ogof Nadolig Ogof Nadolig is a cave in the Alyn Gorge near Cilcain, Flintshire, Wales. It is mostly crawling, long, and ends with a shaft up to the surface and a locked manhole cover. Nearby, but closer to the river, are the caves Ogof Hesp Alyn and Ogof He ...

form the caves part of the Alyn Valley Woods and Alyn Gorge Caves SSSI.

References

* * * {{cite book , author = Waltham, A.C., Simms, M.J., Farrant, A.R., Goldie, H.S. , year = 1997 , title = Karst and Caves of Great Britain , pages = 262–4 , publisher = Chapman & Hall, 2-6 Boundary Row, London SE1 8HN, UK , isbn = 0-412-78860-8

External links

United Cavers Exploration Team

North Wales Caving Club

Countryside Council for Wales
* http://www.cowdery.org.uk/hesp.php Hesp Alyn Landforms of Flintshire