Bijele sige

45.855153°N 15.863263°E / 45.855153; 15.863263 Bijele sige, also known as Bjele sige jama and Jama bijele sige,[1]: 328  is a 27 m deep pit cave with horizontal extensions[2] on the Medvednica massif.[3]: 24  It is located in an area with many pit caves, but is one of the largest among these,[3]: 26  and is distinguished by complex horizontal passages, which bring the total length of the cave to 94 m.[3]: 27  The cave is under special protection, and is closed to the public.[4]: 106 

Description

The entrance to the cave is at 534 m above sea level, and its deepest point at 507 m above sea level.[3]: 26  The entrance is narrow, at only 1.5×0.6 m, widening after 2 m until it becomes a chamber by the end of the 10 m drop.[3]: 27 

The entrance chamber has a mound of soil, branches, and leaves at the bottom and extends both to the northeast and to the west consisting.[3]: 28, 30 

To the northeast, the passage leads to a chamber with a small drop and smaller chimney above. This turns south and ends in narrow, impassable canal.[3]: 27 

To the west, there is a side-passage to a pit with about 15 m of vertical elevation difference, most of which below the entrance to the pit.[3]: 27, 30 

History

The cave was explored and mapped on 18 May 1996 by the Speleološki klub "Željezničar",[3]: 4  and again but with a 3D point cloud by a team from the Faculty of Science at the University of Zagreb in 2019–2020.[3]: 9, 32 

Being near the city of Zagreb, the cave has been used for the training of vertical cavers in Single-rope technique, including on 7 November 1998,[5] and again in the spring of 2000.[6][7]: 82 

Climatology

The average temperature in the cave is 9.8 °C (49.6 °F), with a relative humidity of 95% outside of the entrance chamber. No measurable airflow has been detected.[3]: 29 

The maximum radon concentration is about 800 Bq/m^3, which is much lower than some nearby caves.[3]: 29, 34 

Geology

Bijele sige formed in Middle Triassic layers. including limestone, marlstone, chert, tufa, and tufite.[3]: 24, 27 

It formed away from fault lines and above the local erosional base as the result of denudation.[3]: 38  It is under mainly hydrological conditions, as a vadose feature, although the cave is no longer hydrologically active today except through seepage. But two crevice systems are found in the cave: one 60-240° followed by the canal beneath the entrance, and one 10-190°. Both of these are nearly vertical. This has resulted in much of the cave having a triangular cross-section with a floor covered in eroded stones.[3]: 24, 28 

The cave is decorated with speleothems, in places as thick as 3 cm, including stalactites, stalagmites, pillars, curtains, toothed curtains, cave pearls, tubular straws, moonmilk, cave popcorn, and other concretions.[3]: 27  The decorations are so pervasive that they obscure the stratigraphy of the cave.[3]: 28 

Fauna

The woodlouse Mesoniscus graniger has been recorded in the cave.[1]: 244 

See also

• List of caves on Zagrebačka gora

References

1. Bedek, Jana; Gottstein, Sanja (2011-12-31). "Katalog i atlas špiljskih kopnenih jednakonožnih rakova (Crustacea: Oniscidea) Hrvatske" [Catalogue and atlas of cave-dwelling terrestrial isopods (Crustacea: Oniscidea) from Croatia]. Natura Croatica. 2 (2): 237–354. eISSN 1848-7386.
2. Speleološki klub Željezničar (2016). "Jama bijele sige". Katastar speleoloških objekata Republike Hrvatske.
3. Vidić, Pava (2020-05-25) [defended 2020-02-27]. Morfogeneza krškog reljefa na području Družanice i Drenovače (Zapadna Medvednica) (Thesis). Zagreb: Prirodoslovno-matematički fakultet Sveučilišta u Zagrebu.
4. Javna ustanova Park prirode Medvednica (2023-08-31). "Sažeti pregled prirodnih speleoloških i antropogenih objekata područja obuhvata PU 5000". Plan upravljanja Parkom prirode Medvednica i pridruženim zaštićenim područjima te područjem ekološke mreže (PU 5000) 2024.-2033 (PDF). pp. 201–202.
5. Bosner, Nela (1999) [2000-01-02]. "Speleološka škola '98". Speleolog (46–47): 72. ISSN 0490-4109.
6. Dečak, Vlasta (2001). "Speleološka škola SO-a HPD "Željezničar" u proljeće 2000". Speleolog (48–49) (published 2003-02-02): 92–93. ISSN 0490-4109.
7. Dečak, Vlasta (2001). "Tajnički izvještaj za 2000. godinu". Speleolog (48–49) (published 2003-02-02): 81–83. ISSN 0490-4109.

Further reading

• Vidić, Pava (2020-05-25) [defended 2020-02-27]. Morfogeneza krškog reljefa na području Družanice i Drenovače (Zapadna Medvednica) (Thesis). Zagreb: Prirodoslovno-matematički fakultet Sveučilišta u Zagrebu.