The Kogelbeen Cave forms part of eight caves on the dolomitic Ghaap Plateau of the Northern Cape, South Africa. It is commonly known as Kogelbeengrotte in Afrikaans. The cave is located on Kogelbeen Farm in Pixley ka Seme District Municipality. It is the longest known cave in the Northern Cape with a length of 788 meters. The Kogelbeen Cave has a diverse fauna with over 39 species living in five life zones within the cave.
The cave was first described in speleological literature in 1964. The cave is classified as a South African Natural Heritage Site under the South African Natural Heritage programme[1]
The total cave length was measured at 788m (2,585feet). The cave entrance was measured with a 90x doline which leads to a 30x sinkhole. The floor slopes at a depth of just less than . The doline walls have some holes; however, the main site of the cave starts at the deepest and southern part of the doline. The dry passage is a short and dusky section above the entrance on two levels, which leads for in an eastward direction. There is a collapsing overhang to the north of the cave. The main cave sharply descends to a small chamber which is approximately . Along the north wall of the main chamber is a small hole in the floor. This hole leads to a narrow and moist passage known as the CO2 passage. In this passage, lethal CO2 levels are reached after penetration of a depth of . These lethal levels of CO2 prevented further exploration. The main cave continues into a main chamber which is approximately at . Southeast of the main chamber lies a long passage called the bat passage, which slopes upwards for about . There are a few minor parallel passages linking with the bat passage. The passage has a very high ceiling which is more prominent towards the end of the passage. Westward of the main chamber lies a small crawlway which leads to a low and wide passage called the water passage. The water passage is filled with numerous shallow seepage pools. The water table is reached at .
The 1980 Hitchcock survey differs from the Irish & Marais survey with regards to the CO2 passage. Hitchcock penetrated the CO2 passage all the way to the water table, but makes no mention of the lethal carbon dioxide levels. The air composition is described as 'very good'. Hitchcock measured the water table level in the water passage at 53 m unlike the 57 m measured from the Irish and Marais survey. The water level in the CO2 passage is measured at .
The current lethal CO2 levels make it near impossible to confirm Hitchcock's measurements of the carbon dioxide passage.
The main chamber has a temperature of ; the temperature rises to in the bat passage and ultimately in the water passage. The relative humidity in the water passage and the bat passage reaches 100%. The humidity drops to 98% in the main chamber and 80% in the entrance passage. The water temperature of the main pool is . Subjective commentary on the carbon dioxide levels over time indicate an increase in CO2 over the past two decades. Hitchcock reported no CO2 levels after penetrating both the water passage and the carbon dioxide passage in 1980. Irish and Marais reported high CO2 in the water passage and lethal CO2 presence in the CO2 passage in 1991. The survey in 1997 found the water passage to be even more uncomfortable with the high CO2 composition of the air and the CO2 passage impossible to survey.
There are five life zones in the cave that are distinguishable namely:
Animals found using the doline and entrance of the Kogelbeen Cave include:
The doline serves well for moisture-loving creatures who would otherwise not survive in other areas of Kogelbeen.The Kogelbeen cave also functions as an important bat roost being home to three bat species, including the common bent-wing bat with a population of over 60,000, the Geoffroy's horseshoe bat and the Darling's horseshoe bat, with a combined population of about 5000.[2] Other bat species found include:
These bats are mostly found in the main chamber as well as the bat passage. Considering the large population of bats, unexpectedly thin guano deposits are found.
Species that are dependent on the guano deposits include:
Detritivores that feed on older guano deposits include:
Predators in the Kogelbeen Cave include:
Parasites in the Kogelbeen cave include the mite of the Argus species Argasidae, which feed on the birds and bats of the cave.
Aquatic fauna in the cave include stygobiotic amphipod Sternophysinx Basilobata, which is only found from Kogelbeen.
There is a mammal checklist of the species found in the cave at the Bloemfontein National Museum.[3]
The community members around the Kogelbeen cave believe that an unspecified person died in the cave. It is believed that there is an unknown disease that exists in the cave. Smith reported that some of the members of his team fell ill due to histoplasmosis. Hitchcock's party used masks as a preventative measure against unknown diseases. No recorded members of the Irish and Marais party were affected by illness from the Kogelbeen cave.
Griekwastad publicity association has sought assessments of the cave as a possible tourism area. Factors that result in the cave being unfavourable for tourism include difficulty in movement around the cave, lack of cave formations, unpleasant CO2 conditions in some areas, and threat of disease. Fishing enthusiasts frequently use the areas in the cave for fishing using a man-made outpost structure. Further tourist development would result in a major loss of the bat species, thus threatening the rest of the fauna.