dong Danwandong - 大碗洞

Détail


Nom de la grotte : Danwandong - 大碗洞
Autres noms : Dan Gui Ba
Province, Préfecture, District :
Chongqing 重庆, , Wulong 武隆县
Latitude Nord - Longitude Est :
29.24169 - 107.93974
Altitude (m) : 750
Développement (m) : 1 729
Profondeur (m) : 309
Profondeur - / + (m) : 0 /
Volume (m3) :
Géologie :

1Entrée : Danwandong 大碗洞,

Carte



Description 1



2km NE of Tianxing. The entrance is situated at the base of a large limestone amphitheatre. A strong draught can usually be felt some distance away. (A black hole back along to the right of the amphitheatre is merely a rock shelter.

A stream flows intermittently into a door like opening of 4m by 2m. A passage of similar dimensions leads after a short distance to an 8m climb and the first pitch - 16.7m. From the base of this two more climbs of 2m and 5m lead to an 80m by 40m chamber. The stream runs around the side of this chamber in a gorge carved out of massive sediment banks. There are several stalagmites over 5m and a pit for nitrate extraction. Climbs down over flowstone rejoin the stream which then drops through a circular hole in a false floor to the second pitch -13m.

The second pitch lands in a small chamber followed by a short meandering passage of 2-3m diameter. This emerges into a 40m high 5m wide phreatic main passage descending at 45 degrees. Extensive calciting is present but the passage is clean washed and shows evidence of massive flooding with 2m diameter stalagmite bosses having been broken off.

Upstream decreases in size until an aven is met. Downstream progress is made by scrambling down flowstone to the third pitch - 20m against a steep calcite ramp. This lands in a chest deep pool (depending on water levels). After further climbs the stream sinks in boulders into what maybe an underlying passage. The main passage continues down to another steep ramp and the fourth pitch - 40m. A small phreatic passage at the head of the fourth pitch leads to a balcony overlooking the underlying passage. At the bottom of the fourth pitch climbs down reach an area of sedimentation and the roof eventually lowers to a low crawl. This continues for 50m gradually gaining in size until it joins a stream passage flowing left to right.

Downstream continues as a 4-5m wide phreatic tube until it enters vadose rifting containing committing ducks/sumps (in the wet weather of 1996). Upstream the passage increases in size to become a large chamber. The bedding roof of this is exceptionally flat and dips at 40 degrees. A waterfall enters which maybe the stream that sinks before the fourth pitch. Another passage joins downstream but is unexplored. It may connect back to the higher passages or not! A wall of stalagmites across the end of the chamber conceals a large passage initially 30m by 30m descending at 45 degrees. Large amounts of water flow through this whole area in times of flood as evidenced by recent vegetation and tree trucks found here.

The large passage continues but rapid downcutting cuts the floor away. A high level route can be seen but has not been followed due to the lack of floor. Ducking under a boulder leads to a 8m pitch which lands in a 2-3m wide passage. There is a 2m diameter phreatic tube, a narrow pitch and several small inlets here which are unexplored. The way that has been followed goes through a phreatic maze. This is typically of 4m diameter passage which occasionally climbs back to the larger passage above. Eventually an active vadose canyon is entered 20-30m deep and 3m wide. This has been has been pursued down several cascades and pools and is ongoing with no real obstacles other than possible deep water.



Analyse :

3292 caractères - lu : 2 Fois


Bibliographie 2



http://www.brianjudd.pwp.blueyonder.co.uk/china:china96/jaingkou/wulong3/wulong3.html#top

Site sur les projets China-Caves et notamment les expé Yangtze Gorges expeditions 94 et 96 et les perspectives. Topos, photos, cartes, descriptifs, anecdotes...
Source : Web

http://www.hongmeigui.net/
http://www.hongmeigui.net/
Site sur les campagne d’expéditions du club de Hong Mei Gui. Dans les provinces du Guizhou, Guangxi, Yunnan. Explorations dans les comtés de Leye, Nandan, Guilin. Données chiffrées sur les cavités topo données topo et photo chronique d’expédition.
Source : Web


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Expédition 1


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