Provided for non-commercial research and educational use only. Not for reproduction, distribution or commercial use. This chapter was originally published in the book Encyclopedia of Caves, published by Elsevier, and the attached copy is provided by Elsevier for the author’s benefit and for the benefit of the author’s institution, for non-commercial research and educational use including without limitation use in instruction at your institution, sending it to specific colleagues who know you, and providing a copy to your institution’s administrator. All other uses, reproduction and distribution, including without limitation commercial reprints, selling or licensing copies or access, or posting on open internet sites, your personal or institution’s website or repository, are prohibited. For exceptions, permission may be sought for such use through Elsevier’s permissions site at: http://www.elsevier.com/locate/permissionusematerial From Alexander Klimchouk, Krubera (Voronja) Cave. In: William B. White and David C. Culver, editors, Encyclopedia of Caves. Chennai: Academic Press, 2012, pp. 443-450. ISBN: 978-0-12-383832-2 Copyright © 2012 Elsevier Inc. Academic Press. Author’s personal copy KRUBERA (VORONJA) CAVE 443 KRUBERA (VORONJA) CAVE B1800À1900 m. This is an arena of classical Alpine- Alexander Klimchouk type karst, a glaciokarstic landscape with numerous glacial trough valleys and cirques, with ridges and Ukrainian Institute of Speleology and Karstology, Simferopol, peaks between them. The bottoms of the trough val- Ukraine leys and karst fields lie at elevations of 2000À2350 m, and ridges and peaks rise to 2500À2700 m. The high- est peak is the Peak of Speleologists (2705 m) but INTRODUCTION the dominant summit is a typical pyramidal horn of the Arabika Mount (2695 m). Some middle- to low- altitude ridges covered with forest lie between the At the dawn of the new millennium, in January 2001, central sector and the Black Sea. A plateau-like Krubera (Voronja) Cave in the Arabika Massif, middle-altitude outlier of the massif in its south sec- Western Caucasus, became the deepest known cave in 2 tor is Mamzdyshkha, with part of the plateau slightly the world, with a depth of 1710 m (Klimchouk and emerging above the tree line. Kasjan, 2001). For the first time, the deepest known cave was found to be outside Western Europe. In the article on Krubera Cave in the previous edition of this KRUBERA CAVE AND OTHER DEEP encyclopedia (written in 2003), when the explored CAVES IN THE ARABIKA MASSIF depth of the cave was still at 21710 m, the present author wrote: “The future possibility of locating a 1 Among several hundred caves known in the Arabika 2000 m system in the area is exceptionally good.” Massif, 15 have been explored below 400 m and five Discovering the first cave on the planet deeper than below 1000 m (shown in Fig. 1C). Several are located 2000 m had been a long-standing dream of cavers within the Ortobalagan Valley, a perfectly shaped, rela- around the world, and this was set in 2001 as an official tively shallow, perched glacial trough of the sub- goal of the Call of the Abyss project of the Ukrainian Caucasian stretch, which holds the advanced position in Speleological Association (Ukr.S.A.), one of the most the central sector toward the seashore (Fig. 2). Since 1980, ambitious and successful exploration projects in the his- Ukrainian cavers have been undertaking systematic tory of speleology. In October 2004 this goal was efforts in exploring deep caves in the Ortobalagan Valley reached, when Krubera Cave was pushed to depth of including Krubera (Voronja) Cave (number 1 on Fig. 1C; 2080 m. In subsequent years, the Ukr.S.A. expeditions 22191 m), and the Arabikskaja System (number 4 on have explored the cave to depth of 2191 m in the main Fig. 1C), which consists of Kujbyshevskaja Cave branch, and also explored the second branch in this (21110 m) and Genrikhova Bezdna Cave (2965 m to the cave, called Nekujbyshevskaja, to a depth of 1697 m. junction with Kujbyshevskaja). Another deep cave in the valley, located in its very upper part, is Berchilskaja Cave (2500 m; number 11 on Fig. 1C)exploredby THE ARABIKA MASSIF: LOCATION Moldavian and Ukrainian cavers. The Ortobalagan AND PHYSIOGRAPHY Valley extends along the crest of the Berchilsky anticline, which dips gently northwest. The Arabika Massif is one of the largest limestone An open-mouthed 60-m shaft, the Krubera entrance, massifs of the Western Caucasus (Fig. 1A,B). It is was first documented in the early 1960s by Georgian located in Abkhazia, a republic that officially belongs researchers, who named it after Alexander Kruber, a to Georgia but since 1992 holds claim to being an founder of karst science in Russia. The early exploration independent state. was stalled by an impassable squeeze in a meandering To the northwest, north, northeast, and east, passage at 295 m which led off from the foot of the Arabika is bordered by the deeply incised canyons of entrance shaft. During the 1980s, the main focus of Sandripsh, Kuturusha, Gega, and Bzyb rivers (Fig. 1C). the Ukrainian expeditions to the Ortobalagan Valley The Bzyb River separates Arabika from the adjacent were Kujbyshevskaja Cave (21110 m) and Genrikhova Bzybsky Massif, another outstanding karst area Bezdna Cave (2956 m) connected into a single system in with many deep caves, including the Snezhnaja- 1987 (the Arabikskaya System). At the same time, these Mezhonogo-Iljuzia system (21,753 m) and Pantjukhina expeditions had pushed Krubera Cave from 295 to Cave (21508 m). To the southwest, Arabika is bor- 2340 m by breaking through a series of critically nar- dered by the Black Sea, with limestones dipping con- row meanders between successive vertical shafts. tinuously below the sea level. During this period the cave received its secondary name The Arabika Massif has a prominent high central Voronja (Crow’s Cave), owing to the number of crows sector with elevations above the tree line at nesting in the entrance shaft. Encyclopedia of Caves. © 2012 Elsevier Inc. All rights reserved. Author’s personal copy 444 K FIGURE 1 (A) and (B): Location and shaded maps of the Arabika and Bzubsky massifs. The sea-floor topography is based on the SRTM30plus data (NASA). (C) Deep caves are indicated by dots and numbers (explained in the text) and major springs are specified by two- character indexes (explained in the legend). Solid black lines show the crests of major anticline folds. Red arrows reflect previous ideas on groundwater basins and flow directions controlled by major fold structures. White and yellow arrows indicate the actual hydrologic connec- tions established by dye-tracing experiments in 1984À1985. From 1992À1999 the explorations in Arabika were major breakthrough by discovering and exploring two suspended due to the Georgian-Abkhazian ethnic con- branches that stretched from the old series in different flict and subsequent turmoil. In 1999, the Ukr.S.A. expe- directions: the Main Branch to 2740 m and the dition recommenced work in Krubera Cave and made a Nekujbyshevskaja Branch to 2500 m. The Main Branch ENCYCLOPEDIA OF CAVES Author’s personal copy KRUBERA (VORONJA) CAVE 445 FIGURE 2 Major caves in the Ortobalagan Valley. Red dots indicate dolines. was quickly pushed farther in 2000: in August to combinations of vadose shafts and steep meandering 21200 m and September to 21410 m. In January 2001, passages, although in places they cut apparently old fos- the Ukr.S.A. expedition explored the cave to 21710 m, sil passages at different levels (e.g., at altitudes of establishing it as the new deepest cave in the world. 2070À2040 m in Kujbyshevskaja Cave, 1200À1240 m in In 2004, the cave was explored to depth of 1840 m in the Main Branch of Krubera, and 980À1150 m in the August, and to 22080 m in October. Further efforts in Nekujbyshevskaja Branch of Krubera Cave, etc.). The the Main Branch led to reaching the terminal sump antiquity of these passages is supported by the ages of at 22145 m in 2006. The current deepest point at speleothems falling beyond the 230Th dating limit 22191 m was reached by the Ukr.S.A. expedition in (.500 ka). Both branches of Krubera Cave are extremely 2007 through diving to 246 m in the terminal sump. In vertical up to the depths of about 1600 to 1700 m (alti- the Nekujbyshevskaja Branch, systematic digging efforts tudes of about 750À650 m). The Main Branch below this in boulder chokes since 2004 resulted in a series of level becomes more inclined, largely following the strata breakthroughs and the eventual exploration to the depth dip, but then it goes steeply down again to the depths of of 1697 m in 2010. Most of the Ukr.S.A. explorations in about 2050 to 2150 m (altitudes of about 200À100 m). Krubera Cave since 1999 have been led by Yury Kasyan. Cave development is strongly controlled by the block- All the large caves of the Ortobalagan Valley belong fault structure. The cave entrances are aligned along the to a single hydrologic system, developed in and near the anticlinal crest (Figs. 2 and 3) but the cave passages and crest zone of the Berchil’sky anticline. The direct connec- shafts are controlled by diagonal and orthogonal frac- tion of Krubera Cave with the Arabikskaja System, tures and faults, and comprise complex winding pat- although not established yet, is a sound speleological terns in the plan view, remaining largely within and possibility. The Main Branch and the Nekujbyshevskaja near the anticlinal crest zone. Two dominant diagonal, Branch in Krubera are largely independent, predomi- SEÀNW-stretching lines are recognizable in the plan pat- nantly vertical, parts of the system which deviate from tern of Krubera Cave.