Branislav Šmida: ..."..."What have you found?" We ask impatiently. For joy and excitement Stano cannot express himself well about depth of the pothole. Abyss! After several hundreds of meters rumbling of a stone disappear in the depth...

Saturday, August 7th, 1993.
By Damir Lacković

We took ropes for further descending, but left 100 metres at the beginning of long pitch, beyond a crawl. Penetrating deeper, at 7.30 p.m. we run out of rope at the beginning of another long pitch. Siniša climbed back to pick up rope left ahead, and was back by 8.30. p.m. We have used the rope on the pitch, to conclude it is the last, at 9.45 p.m., all three of us, descended to the bottom, Damir first, than Siniša and finally Šišmiš.

LUKINA JAMA (PIT)
CAVE SYSTEM LUKINA JAMA - TROJAMA

Lokacija: Hajdučki kukovi, NP Sjeveni Velebit, Hrvatska

Depth: -1421 m

Length (horizontal): 1078 m

Explored by (1993.-1995.): The Speleological Committee of the Croatian Mountaineering Association,
SO PDS Velebit, SO HPD Željezničar, SO HPD Dubovac, SO HPD Mosor, DISKF,
SO HPD Japetić, SSHGD, SD Špiljar, SUK Bratislava

 

DESCRIPTION OF LUKINA JAMA ( MORPHOLOGY)

by Darko Bakšić

Entrance in Lukina jama is a crag dimensions 22,5 x 5 m. From the entrance to Whiskey chamber, at the depth of -320 m it is practically vertical. From the depth of -50 till -320 m on rocky sides could be found tick layers of snow and ice. In the first part of the cave, at the depth of -53 m and -178 m are two side passages. The upper leads into smaller chamber with icy waterfall 27 m high, while lower is meanderic, snowy and steeply goes down till a small lake at the depth of -195 m (to this point Slovaks descended in 1992). Below Whiskey chamber is a pitch 228 m high. On its bottom is a sloppy ledge 27 m long. Here, at -558 m below the surface, is connection with Trojama (Manual II). Thereafter are several minor pitches till traverse at -638 m. Starting from the traverse, a hundred metres pitch leads to a small ledge, yet another pitch of 4 m and there is entrance of a meander wide 3-5 m. Here, at the depth of -743 m the 1st bivouac is situated. Between the 1st and 2nd bivouac is a pitch of a craggy meander shape in its upper part, while it gets wider in the lower part, split by several minor ledges.
 

Ulazni ledeni dijelovi jame (lijevo). Whiskey dvorana na -320 m (sredina) - foto: V. Božić. Uski prolaz iz dvorane na -950 m gdje je bio 2. bivak (desno) - foto: D.Troha.

Bivouac II is at the depth of -950 m, in a chamber 85m long and 70 m wide. On the Northeast side of the chamber a narrowing connects it with the next pitch high 142 m that ends by a sloppy ledge at the depth of -1092 m. Below the ledge at -1102 m is a narrow entrance into Vjetroviti kanal (Windy passage) which is a meander 47 m long going downhill. After passing speleothemic narrowing starts a pitch of 109,5 m, followed by several shorter and finally slope till the depth of -1311 m. Here, the passage ends filled by boulders covered by clay. There is a possibility to traverse the passage a bit higher and bypass. Possibility for finding new space is not high, though. According to the ground plan this part of the cave should be connected with a small side passage, just before the bottom.

The main passage descends from the sloppy ledge at -1097 m through several minor pitches till the point of connection with the 30 m long upstream passage. Follows several minor pitches and big pitch of 95 m. Just before the bottom are two small pitches. At the bottom is a chamber 20 m long and 5 m wide with a siphon-lake in the Southeast direction. Second, smaller siphon is situated across the first. The 1st siphon is dived in length of 57 m where, after an air pocket, starts another siphon.

There are two side passages at the bottom. One is above siphon-lake at the eastern side of the chamber and it splits into two smaller passages, all together 32,5 m long. The endemic leech is discovered here. The second side passage is situated in Northwest part of the chamber 8 m above the 2nd siphon. It separates into two parts, too; one of which is extremely narrow (it has a potential for further progress, but has to be widen, by hilti), the second passage is wider and easier to pass through. Together they are 120 m long.

Bottom of Lukina jama reached so far is just 83 m above sea level, and 10,5 km far from the sea. Further flow of the subterranean streams is probably in the sea direction and submarine and coastal springs in area from Žrnovica to Jablanac.

A 3D crossection of Lukina jama-Trojama, made by D. Bakšić and Dr. V. Kušan.

 

Lukina jama-Trojama topo

 

Description of Trojama ( Manual II )

Branislav Šmida

 

Entrance in Trojama is a crag long 26 m and wide about 2 m. The entrance pitch is 140 m deep, with several side holes, that probably lead into parallel underground pits, still not explored.

Openings at southeastern side of the pothole are very interesting, because could be connected with the cave no. 15, which would increase the depth of the system for 3 m.

At -140 m starts icy part of the cave wide from 0,7 till 6 m. At the point where ice stops is a narrow entrance into passage called Grmač. If ice breaks, it could close the entrance. The meander is easy to pass in its middle part, but in the lower part is very narrow. After meander is a vertical named Plana stovka (Bad hundred) deep 80 m, which ends by a shallow lake. Thereafter are several smaller pits from Baldachyn till Monzunova šachta (Monsoon pitch). On the whole part from Grmač till Monzunova šachta one could not see the ceiling.

Baldachyn is a side passage with a wig where, in need, is possible to make a bivouac. Monzunova šachta, 160 m deep, connects with Lukina jama at the depth of -558 m, or at -595 m if measured from the entrance of Trojama. Stream starts here, than stronger or weaker, flows through whole lower part of the system. The depth of cave system, measured from the higher entrance is -1392 m.

Geological profile of  Lukina jama-Trojama.
D.Lacković, B.Šmida, D.Bakšić

 

 

A crossection through the Mt. Velebit incuding Lukina jama, Slovačka jama, Velebita, Meduza,
Patkovog gušt, Olimp, Lubuška jama, Ledena jama (2008.) by D.Bakšić

See also new results of the exploration of Lubuška jama and possibility of connection with Lukina jama-Trojama.

BIOSPELEOLOGICAL FEATURES OF LUKINA JAMA

By Branko Jalžić

Extraordinary feature of the system Lukina jama is its morphology. It is characterised by vertical shape and great depth of -1392 m. For ecological point of view it is interesting for three micro climatic layers, firstly entrance icy part with the temperature of about 1 °C, secondly, middle part with the temperature up to 2 °C and bottom part with temperature till 4 °C. Important ecological factor is presence of smaller water stream starting at 550 m of depth till the bottom, where are submerged passages. Different organic remedies at rocks in this part of the cave draws a conclusion that water floods space up to several meters above the lowest, summer level. Temperature of water in the lowest part of the cave was 4 °C.

The most important discovery is that of finding endemic stygobiontic leech noticed by Ana Bakšić (Sutlović).
List of discovered animal species in Lukina jama: Marifugia cavatica, discovered new stygobiontic leech that is the most important biological result during the expedition,  Niphargus croaticus, Aplpioniscus hercegowiniensis, Hassia stenopodium, Astagobius angustatus, one specimen of beetle from group Bathysciinae (very similar to genera Radziella known from Biokovo Mountain), Chiroptera: Cavers observed one bat in a narrow pass at -950 m depth.