dong Yanzidong - 燕子洞

Yenze Dong (Swallow cave)
The cave is located 2.2 km SE from Houchang village (Ermu village) and S-SW from the local quarry.
WGS Coordinates . N24.81946 E102
The entrance is located at 2031m.a.s.l on the slope in SW side of the bottom of the uvala 0.4 km long and 0.2 km wide and direction to the long axis NW-SE. It has triangle form and is 5.50 m wide and 3.20 m high. It seems that the cave is a temporary (periodical) sinkhole. The development of the cave is based on 3 main fissures with directions: E-W; NW-SE and NE-SW. The first part is low grade and followed by vertical passage of 3 steps (pits) (P1-22 m; P2-13; P3- 13 m). The native people, intent to use river for water supply, so they rigged the passage with iron stairs, pipes and electric circuit to make possible the water pumping. The stairs lead to the high and narrow in its bottom river gallery. The depth here is 73 m. The first part of downstream passage is low and narrow, the depth of the river reaches 0.7 m. The next 80 m of the gallery are higher (max.18 m) and wider (max.8 m). In the vault arch of the end of the passage in the cave there is a chimney. This is connecting point with the upper level of the same gallery. Further, the passage gets narrow again. In its end the gallery has two levels. In the lower one, the river jump 3.5 m making little waterfall, run 30 more meters and sink in a muddy sump! Here is the deepest point of the cave – 95 m. The higher passage is dry and scandent. It leads to the biggest hall of the cave (55x25x 3-6 m), where the cave branched. The left branch is well decorated by dripstones. The right gallery turned in SW and after 60 m stopped in the edge of the pit (-15 m deep) which connect with the lower part of the same passage.
The first 25 m of upstream passage are 9 m high. The penetration is realized on the morphological level 3-4 m upper from the river bed. The next 150 m of the cave meandered. The passage is ~ 5 m wide and 2-3 m high. The river covered approx. entire surface of the gallery, but is not deeper than 20-30 cm. Lateral from the river bed there are clay-sand deposits with different thickness. The walls and selling are covered by flowstones. Further there is a crossing marked by little in area but deep (more than 2 m) lake in the right (South) side of the gallery. Up form the lake start a meandering, relatively low (1.20 m) and light scandent dry gallery. It is covered by clay and sand. There are reliable evidences, that in dry period this passage is influent to the main river. The gallery finished with a little lake. Few meters before the end the cave branched again. The opening of the passage is in left, where begins rather scandent and narrow gallery (length 70 m). The final few meters of the passage are horizontal and ends with a pit (diameter 4 m; depth – 15 m). The bottom is blind – there is the end of the passage.
Ahead from the crossing there are 110 m of wide and enough high (2-3 m) passage, which leads to a room with a big column in it. Here the gallery turned curtly in left (North) became low and narrow and not passable. Behind the column there is appendix. The passage is developed at narrow (1.30 m) and high more than 14 m fissure. Here is the end of the cave. The total length is 1514 m. Depth – 95 m. The cave is surveyed at 24 October and 8 November 2012.

Alexey Zhalov edited by, Chinese-bulgarian-greek speleological expedition “Gaolingongshan 2011” in Yunnan province, China. (2012)
48p., 65 photos couleur, 9 figures, Bulgarian Federation of Speleology, April 2012.
Analyse :
This report details the joint Chinese-Bulgarian-Greek expedition carried out by members of Bulgarian Federation of Speleology and Yunnan Institute of Geograhpy & China Exploration & Research Society (CERS ) Yunnan branch, Yunnan Province, China. Yunnan 2012 was a 4-week, 13 person winter caving expedition. This expedition involved a first speleological exploration of the caves of Gaolingongshan and to known some unexplored areas on the mountain. Major finds included the logging and exploration of 8 new caves on the territory of the mountain and its vicinity. The most significant caves which the team explored were far from the main exploration area close to Kunming city. Among them are the longest caves explored during the expedition Yenze Dong (Swallow cave) – 1514 m and Da Shi Dong (Big rock cave) - 1394 m. During the expedition were mapped 11 caves with a total length of the galleries 4972 m and depth 429.60 m (-318.2/+ 89.4)

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