dong Wudidong - 无底洞

Take the main road north of Caobo for half an hour to a bamboo-logging operation. Follow the logging path on the left hand side of the road first over fairly level ground and then ascending more and more steeply through woods until after 30-40 mins you reach cleared rice fields. Follow the track around the bottom of the fields, and where it cuts uphill along the right hand side of the fields take the third track contouring off to the right. After 10m turn left off the path and head uphill through the brush for 30m. Wudi Dong is a narrow cleft in the limestone pavements with two chock-stone bridges over it.
Wudi Dong is a strenuous grade 4 yorkshire pot that has somehow been transported to Hunan.
A 2mx6m daylit hading rift inhabited by a rat and a toad drops down to a floor of organic debris. Immediately to the east the rift narrows considerably, forming the head of the Rift pitch which is constricted until the rebelay at -7m (left hand bolt is wobbly). The Rift pitch lands on a 4m wide floor of cobbles. The way on is a wriggle down through a small hole which on cold days has an audibly howling draft (note the unused bolt). Here a further 2m climb down gains the largest chamber in the cave and the head of the Big pitch. A sling and rope protector around a large calcited boss and a bolt in the right hand wall protect the aproach to a y-hang from bolts in the ceiling above the pitch. Two bolt deviations provide a clean hang to the rebelay at -14m from which there is a further 26m of surprisingly spacious descent.
The Big pitch lands in Toad Hall, named for a sociable but rather emaciated toad which lives there.
From Toad Hall there is a choice of ways on: a climb up and traverse or a grovel through a small muddy hole. Both rejoin immediately in meandering rift in which it is necessary to choose the right level for forward progress. After 20m an aven enters and there are 3m of beautifully clean washed white limestone before the cave returns to its typical character. After a further 12m the way forward is blocked by an ascending ramp of mud and cobbles. The way on is a small hole in the right hand wall which was dug open to gain a short section of constricted vertical meanders. Up and to the left leads to a hole which is too small. The way on is down and then left, which ends in a short climb down to a more comfortable sized chamber with three passages going off. First, to the south boulders and cobbles cemented by mud can be climbed for 10m to the base of a drafting aven, one wall of which is a large choke which has not been pushed to a conclusion. Second, to the west a very tight rift is an oxbow rejoining the first passage at the base of the aven. Third, to the east a climb up through a hole followed by a crawl ends in a drafting dig in mud and cobbles. This dig was enlarged for 1m to gain 3m of crawl. Here the left hand wall hades and forward progress was blocked by fill of cobbles and small boulders entering from the right in several places. Sticking to the far left, cobbles and mud were removed for 3m to form a sternum-scraping flat-out crawl in a mud puddle which pops out at the bottom of a 4m high drippy aven which is immediately followed by a 1m long squeeze over mud and boulders (now enlarged) to a largish chamber/space between boulders. Here the boulder choke proper begins. There are numerous leads in the choke which have not been checked, but most seem only to lead to more spaces between boulders. The way on is to go steeply downhill, generally staying to the right, until a small stream is met. Upstream has not been explored. Downstream the passage gradually enlarges, going from crawling to stooping until an aven enters (two possible high level crawls) and it changes character to tall, narrow rift descending in short steps. It briefly enlarges to 2m wide, but a 3m climb down to the left of a large slab regains the narrow rift. After a further 15m, the water drops down a narrow slot, while a traversing leads to the head of an undescended 12m pitch where the water can be seen dropping down into a 2m? diameter pool. Continuing on the traverse level over the top of the pitch, a thrutchy climb down (needs bolted handline) leads to more narrow descending rift and a small stream which is possibly higher and smaller than the main rift streamway. This has not been pushed.

EML 2003.11.17

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