BAK PUK, South Lungrang

Location

A spacious stream cave entrance at the end of a dead valley leads to crawls, a duck, and a silted up pool. ETYMOLOGY: The Mizo "bak buk" translates into "Bat Cave" and is applied by the local population to both of the two caves near Lungrang. »Tluangrema« is the name of a member of the Lunglei Adventurers Association, who is said to be the first person who ever entered the cave. SITUATION: The village South Lungrang (note 1) lies 30 km approximately south along the road from West Rotla (note 2) and 70 km from the town of Lunglei (22°53'N: 92°45'E). There are two caves called Bak Puk. Both caves lie in the north of the village, and vertically some 50 m lower down. They are developed in a block of Miocene - Pliocene mud- and sandstones that dip by an estimated angle of 15° to the approximate south-west. Its surface is incised with a series of parallel gullies and covered with bamboo jungle. This, however, might be found to have been recently slashed and burned. To reach either of the two caves, a knowledgeable guide is necessary. The first and more famous Bak Puk (Lungrang) lies about 2 km along a footpath north-west of the village (in a direct line 1.67 km on 331° from the church in the old / upper village) and not very far from the upper edge of the cuesta. CAVE DESCRIPTION: The comparatively large cave entrance (10 m wide, 7 m high) is by far the biggest of Mizoram. It lies at the lower end of a dead valley. It gives access to 50 m of large river cave (10 by 5 m, to 255° / -10°) which runs into a cross rift with a 10 m aven to the right (north-west) and sort of a boulder choke ahead. A 2 m descent on the left hand side leads into 35 m of hands and knees passage (on average 1.5 by 1 m, 255°, -12°) to a wet 10 m crawl "culminating" in a dirty duck (10 cm airspace) through a slurry of mica rich mud and decomposing vegetable matter. Popping out, a series of slippery and bat guano covered fallen slabs are to be negotiated (3 to 8 m wide, on average 2 m high, 45 m long) which reach the shore of a terminal lake (6 by 2 m, 15 m long). At its distal end sinks the ceiling below the water level. SPELEOLOGY: The host rock showed no visible reaction with hydrochloric acid but a few and very short stalactites (1 cm long straws on the ceiling of the terminal lake) indicate at least traces of chemical solution. The cave originates most likely from piping failure. It is developed along two parallel and strongly bend faults (walls expose slickensides dipping between -30 to -05° to 165°, south-east uplifted) which cut through multiple layered, arenaceous and mica rich mudstone alternations (exposed on the ceiling). The floor is covered with fallen rectangular boulders, sand, mud and water (19°C, stagnant and putrid at the end of the dry season: A backup zone). CAVE LIFE: A few solitary bats (Chiroptera), crickets, shrimps (transparent Crustacea with pigmented eyes). Mud piles indicate soil dwellers (earthworms?). Herbert Daniel Gebauer - 28/02/2016

NOTE 1: Old South Lungrang 22°43'46.1”N: 92°39'01.9”E: 650 m (Gebauer, GPS Garmin 12) and New South Lungrang 22°44'04.0”N: 92°38'38.1”E: 750 m (Gebauer, GPS Garmin 12). NOTE 2: W. Rotla 22°50'N: 92°37'E (RALTE, C.W. undated circa 1970: Mizoram leh a Chhevvêl). Herbert Daniel Gebauer - 28/02/2016