dong Longsankeng - 龙三坑


Nom de la grotte : Longsankeng - 龙三坑
Autres noms : Three Dragon Pits, upper
Province, Préfecture, District :
Hunan 湖南省, Zhangjiajie Shi 张家界市, Sangzhi 桑植县
Latitude Nord - Longitude Est :
29.68874 - 110.71556
Altitude (m) : 851
Développement (m) : 3 344
Profondeur (m) : 177
Profondeur - / + (m) : 0 /
Volume (m3) :
2Entrée : Longsankeng 龙三坑, Longsanseng Lower 龙三坑,


Description 1

At the base of a depression immediately uphill of the road to Xilian. From the road to the Yu Jing mine, a slippery gully descends to the pitch-head, where a choice of several large trees serve as belays. The route continues on-rope down the gully, with two rebelays (a single bolt, then a y-hang) giving a final 10m hang to the floor of the doline.Three routes lead off. The water from the entrance waterfall flows immediately into a large passage, Red Rock, where it joins another stream which can be followed either up or down-stream, while on the opposite side of the doline, a smaller fossil passage leads off to the Scoopatorium.Upstream can be followed for around 150m in 10m wide passage featuring a large oxbow at the start, before a boulder choke is met; the stream can be followed to the left beneath the choke for some distance before being blocked, while near the top of the choke a route through boulders regains the stream at the foot of a small waterfall, which has not been scaled.Back at the end of the oxbow, a climb up to the west enters a dry inlet passage. This is initially keyhole-shaped, but soon looses its floor trench to become mud-floored walking passage up to 5m wide. After 50m s branch to the right soon closes down, while the main route has been followed for a further 70m to where beyond a climb up and back down there are two ways on; an unpromising crawl at floor level [QM C], and an 8m climb up into the continuing passage which seems to be the source of the strong draught.Downstream immediately enters a large passage, up to 50m wide, where progress is made by climbing over a jumble of huge blocks. After 300m the passage starts to narrow; 50m further on it becomes a clean-washed rift 2 to 4m wide, with exploration halted by a deep pool after 40m.After 50m of 5m wide mud-floored walking passage, the passage enlarges and becomes boulder-floored. After 100m of 20m wide passage, a rubble slope almost blocks the way. Just before the rubble slope, a walking/stooping passage to the right, which appears to have been mined for nitrates, goes for 80m. A small inlet on the opposite wall has been followed for 10m and continues.The rubble pile can be passed either by following the right hand wall through a gap about halfway up the rubble heap, or by clambering right over the top. Beyond the rubble, the passage turns south-west, and for the next 100m descends with a small stream flowing along the right-hand wall. The stream crosses to the left-hand wall, and 60m beyond there is a junction at an area heavily mined for nitrates, containing several nitrate pits and the remains of a wooden hut.Straight ahead from the nitrate pits, a high level way on appears to be impossible to reach, but a devious route up exists at the back of a cleft. 40m of walking passage, passing a small passage to the left and a choked pit on the right, reaches a climb up on the right to enter a 3m wide phreatic tube with a good draught.After 20m the phreatic tube enters a larger pasage through a small hole at the base of an unstable rubble heap. The obvious way on at the top of the rubble heap is 5 to 10m wide, but ends after 60m in a mud choke. The source of the draught is back at the bottom of the rubble slope, opposite the entry point, where a sandy slope down leads to a dug-out crawl in which a strong draught and loose sand make eyes-closed crawling a necessity; beware, the crawl emerges high up on the east wall of Red Rock passage.Back at the nitrate pit junction, a climb down to the left past huge boulders gains the continuation of the large passage, now up to 30m wide and heading south. After 150m a large slope down reaches a large stream which almost certainly comes from Red Rock passage.Upstream is initially cobble-floored, passing a small inlet on the right and a tall, wide rift on the left, which might be enterable with combined tactics. Beyond this point the passage becomes a clean-washed rift in which it is possible to traverse upstream above a deep canal until the walls get too far apart after 20m.Downstream, 20m wide cobble-floored passage is followed for 80m before turning east into a 3m wide rift, where a deep pool stopped progress after 20m.Below the road to Yu Jing mine a 20m diameter heavily vegetated depression slopes down to an entrance in the southeast corner.The Crackers'n'Cheese section starts at the Lower Entrance of Long San Keng and is in a heavily vegetated sink that required some bushwhacking to access. The 1.5m tall by 2m wide opening leads to a mass of boulders sloping down, creating a few climbs and short pitches. The first pitch is a small hole along the southeast wall of the cave. A boulder at the top can be used as a thread to rig the 7m pitch. The last bit of the pitch can be done off rope to avoid wear on the rope by accessing a short climb further down passage along the southeast wall. There may be a small lead going back towards the entrance along this wall between the breakdown. After this pitch is a short ledge with many boulders, with which a Y anchor can be rigged for the next 7m pitch. This pitch is created by a huge boulder and requires two to three rope pads. There is a small ledge at this point. A boulder slope to the northeast continues pass a 4m climb up a breakdown wall and has a small trickle of water.An easy climb down from the ledge below the 7m pitch ends on a small 2nd ledge that has a climb that doesn't require a handline but is made much easier to negotiate the bottom of the climb since the rock is very slippery. At this point the morphology of the passage changes as the passage trends to the south-southeast and becomes a borehole. The is a field of boulders and the broad, flat ceiling has many small stalctites. The north end of the passage is almost choked in breakbown with a small lead between the west wall and the breakdown. A dome along the east wall may also give access to small passage high above. There is a small stream flowing to the south and sinking at a large plateau of sand that rises above the gravel and boulder filled streambed. The passage here is about 20m wide and 10m tall. There are a few formations, nitrate pits, steps, and a little stone house made from pieces of formation and flagging stone. At the end of the passage is a junction between a high fossil passage to the east and the active stream passage to the south. Station M18 marks the junction.The fossil passage is accessed by walking up a short boulder/gravel slope that has a 1m wide stoop walk at the top. This opens into a small chamber that is 10m in diameter and 2m tall. The ceiling is white and veined with yellow, like white crackers and cheddar cheese. The floor is sand and there were three medium-sized black bats. This is followed by 50 more meters of sandy-floored passage, 10m wide and 3m high. The floor then changes to gravel as the passage splits. The slope to the northeast ends in a small chamber 8m in diameter with a dirt floor 2m ceiling. The lead to the southeast pops out to a crumbly 20m climb.Back to M18 the stream passage to the south-southeast is 5m in width and has water running through the gravel along the floor. After about 40m the passage branches. The west branch has a 7m pitch and the south branch continues 20m, has two ankle deep pools and three leads. One lead is to the east and is high on a ledge. The other two are the up and downstream of a stream passage that is 10m wide and below a 4m pitch. From the end of the Crackers 'n' Cheese, the passage corkscrews down to the right to a boulder filled active lower stream passage: Taco Salad. Upstream climbs steadily passing a noticeable boulder into a 50 meter wide junction room with many leads. Following the upstream lead, the passage fluctuates in width and passes a sizeable bedrock column. High canyon passage follows with noticeable black-and-white striped walls to a 7 meter waterfall with has obvious passage beyond (unpushed). Back at the junction room, the southeastern lead Bean Burrito, which has a considerable draught, ends in a to a 4 meter climb down (v. long handline required) and a main drain passage which has not been explored. Downstream from the corkscrew area the Taco Salad streamway almost immediately goes down a narrow canyon. Above the streamway to the northwest there is a maze of sandy flood-overflow passages (10 o'clock Series) that trend back to the stream, all of which end in pitches.

EML DRJC 2005.03
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Expédition 1

Cette grotte a été identifiée ou explorée au minimum par cette (ces) expédition (s) :