AREA 38: Yen Minh North - Mau Due

YMn1: Ban Ma 1
Development: >300 m
Denivelation: -

Exsurgence of an important river. The river comes out of the mountain, but we can not enter here. 10
m higher we found an old entrance which gives to a large chamber with huge blocks. In the chamber
we hear the large river flowing. Fast streaming water comes out a boulder choke. To the right we
follow a by-pass which is dry for the moment. A relatively larger gallery is going up. A bit further
the gallery becomes lower and a muddy sump is reached. To the right a muddy slope is going up
again and can be followed, but we need rope. We decide to go back to the river in the larger chamber
at the entrance. By measuring the steep slippery slope we had a small accident and didn’t make the
survey of what we already found.
It is obviously a very promising cave, but with a slippery floor (watch out on steep sloops). To be
continued next expedition.

YMn2: Ban Ma 2
Development: 117 m
Denivelation: -60 m

Large collapsed fossil chamber (open air) with small cave. Near the intersection of sandstone and