Plandiste - Ponara

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PLANDIŠTE - PONARA (~46 km from Mravinjci)

Village Golubac, hamlet Mitrića, near Valjevo, western Serbia 

History and geography research

The area where is a cave Plandište - Ponara includes Bačevačku karst area, which belongs to the Podgorina of Valjevo and extends southeast of Valjevo. Cave can be reached via road Valjevo-Rajkovic. From the village Rajkovic you need to turn right through the road to village Golubac. The entrance of the cave can be reached by car. The entrance is at 370m above sea level. The cave is developed in the first part of the valley, which the locals call Golubsko field. Karst valley where the cave is developed provides to the northwest. In her bottom is a series of valleys lined, whose depth does not exceed 10m. Limestone mass is mostly covered by alluvial deposits.

The locals didn't know about cave, because seven entrances were clogged with organic material, and river sediments. There were known only Vigled over discharged through the sinkhole zone, it was assumed that it was a shallow pit. In September in 1979.  the water broke the lowest abyss. That was used by Speleological Group of Research Society "Vladimir Mandić - Manda" to explore the longest cave in Valjevo region, at that time. Length of the main channel of the cave is 524 m and the total length of all channels is 968m.

Morphological characteristics

Ponara is the remaining of old river flow, which during his  karst processes in this area ceased to flow. The river lowered her bottom and made very wide area of the sinking, even seven abyss on the length of 70m. All entrances, except the lowest, are overwhelmed with fluvial sediment. Old meandering channels are merging into one at a distance of 40m. Their width is similar and it  doesn't exceed 3m. Only the two lowest channels with its beginnings built rooms which are elongated in the same direction.

Hall of the lowest channel is 10m long, 22m wide and ceiling height is 6m. The bottom of the hall is buried in huge, fallen blocks which is indicating in vertical growth of the cave. This evolution of the entrance hall caused the emergence  of Vigled, in the initial part where the limestone layer was thinnest. The opening of Vigled gained a requirement to act as storm erosion and accelerated vertical growth of the hall. From the halls, in the depth of the limestone mass, there are meandering two channels which are connected after 40m. Lower channel that occurs in the middle of the hall begins with pit with depth 3m, and occasionally is active. After the 40m where all channels are connected, the water is entering the compact limestone block and there is only one channel, not branching, along one dijaklaze. His is  on 107. meter wide 5m. On the 101.  the bottom of the cave is covered with a thick layer of fine sand. The walls are polished by abrasive water erosion. On ceiling, which is an average of 10m high, are stalactites. After a narrowing channel in the 132. meter in compack limestone, water intersect a lot dijakliza and build numerous channels. Channels meander in diferent heights and even intersect. Significantly  enlargement, are in places of connection, where can occur smaller rooms. Widest now active channel, 5m wide, and the height of the ceiling is about 3m. The floor is littered with smashed fallen limestone blocks. Since discharged through the sinkhole zone at 224. meter cave meander towards the northeast. From the 224. meter channel changes direction and turns to the southeast . On  264. meter channel splits, the primary extends 27 meters to the northeast, then turns to the southeast and with length of 71m in the 309. meter it rejoins with main channel. Right, the secondary channel meanders to the southeast, and after 45 meters is merged with the primary channel again. After connecting the primary and secondary channels, main channel is rapidly expanding to6 m and a height of 8m. On 322. meter to the southwest separates lateral one with length of 51 m. A ceiling height of the side channel from the beginning to the end decreases from 6 to 1.5m.

The floor is covered with fallen sediment and clay. The ceiling is rich with white stalactites, and the walls are marked by calcite salivs. On 367. meter main channel is extending in a distinct hall, which is 32m long and 11m wide. The bottom of the hall is covered  with limestone blocks and fine sand. The blocks are calcified, and on them are formed stalagmites. The ceiling is rich in stalactites. In far end of the cave, along the channel extends long expansion length 25m and filled with water. From the 395. meter, where the hall ends, the 457. meter of main channel gradually narrows to a width of only 1m. Ceiling height also decreases to 0.8m. In this part of the cave there are no speleothem a channel. On 487. meter behind the narrowing, channel descends through a cascade of 3m deep and again spread to 3.2m. After 4 sharp meander cave channel ends in siphon lake. The lake is wide 5m and deep 3m. Above the lake rises the chimney. There were attempts to dive the lake, but only recent dives have been successful in his overcoming.
The total length of the siphon is 60m with a maximum depth of 8m. Lately, it is recorded a greater amount of sediment in it. Channels that extends after the siphon are not recorded and fully explored.