"THE AMPHITHEATER":
This spectacular hall is named after Mr. Philippus Rudolf Owen, a Pretoria excavation contractor who had purchased the farm Sudwalaskraal in November 1965.

Early in the development of the Sudwala Caves as a South African tourist attraction, it was discovered that the "P.R.Owen hall" had natural air-conditioning and it was also suggested that this, plus its other attributes, would make it splendidly suitable for opera and other drama.

In July 1970 the famous Russian singer, Ivan Rebroff, tested the suitability of the big hall for concert purposes. His remarkable voice, with a range of four octaves, resounded gloriously through the caverns in a series of songs. Afterwards he gave his considered opinion that the acoustics were at least equal, if not positively superior to those of any concert hall or opera house in Europe.

The Sudwala cavern complex is dominated by this chamber with its lofty corridor measuring 150 metres connected to its centre. The chamber itself is roughly circular, 70 metres in diameter and reaches a height of 37 metres to the peak of a dome-like feature in its roof. A stream of fresh, cool air from an unknown source permeates the spacious corridors, maintaining these at an even temperature of 17°C all year round. For
concert purposes more than 500 people could be seated in this
dolomite chamber.
Mr Owen died on the farm in 1972. This hall is a fitting tribute to a man who had the
vision to make the caverns accessable to the public, and who devoted his last years to the protection and preservation of this natural wonder.

CAVE BIOLOGY
Two factors strongly preclude the possibility
of finding true cave animals in the main cave:
a) The cave is extremely dry although it must have been wet when the formations were being developed.
b) The illumination and traffic necessarily present due to the tourist travel drive cave forms into more remote, and to man, inaccessible areas of the cave.
The only organisms that can be seen in the cave along the tourist route are the insectivorous bat the Horseshoe species (Rhinolophus Londeri and Rhinolophus Hildibrandi). There is a colony of about 800 throughout the cave system. They head out at about 19h00 each evening to feed. The bats average a speed of 20 km/h and will fly in the immediate vicinity, a radius of 200 km each night feeding mainly on a diet of mosquitoes. When they return to the caverns at about 4h00 they will have consumed their own body weight, which translates into an average of 800 insects per bat in one night of feeding. They have a life-span of about 24 years, do not carry rabies only lice which help keep them clean. Due to their size they are not a threat to humans.

The algae and ferns in the P.R.Owen Hall and along the tourist trail are not to be considered as part of the biology of the cave. They exist only because of the lights in the cave. From the viewpoint of the professional speleologist their presence is most undesirable since the green stain contaminates the true colour of the formations. Unfortunately it is practically impossible to prevent the introduction of spores and seeds into the tourist
caves. Centipedes and rodents can be seen occasionally in the entrance zone.

THE SUDWALA DOLOMITE - HOW ROCK AND CAVE FORMED
The principle pod of nature is water. The first deposit of this sedimentary rock, was laid down approximately 3800 million years ago. This deposit known as the Malmani Dolomite Ridge, consists of successive layers of erid, shale, conglomerate, chert and dolomite CCaMg (CO3) . This was all laid down beneath water when Africa was still part of Gonolwanaland and eventually left to solidify. A major climatic change or uplift to the earth's surface swept away the sea under which they had been deposited.
Over vast periods of time the water returned and other sedimentary deposits were left in the area. The limestone in this dolomite represents a period when sea water was concentrated to such an extent that chemical precipitation of lime-rich material was possible . For a long time after it had been deposited, the dolomite was
affected only by tectonic/earth movement which folded and faulted. A considerable change began about 300 million years ago. The structural deformation brought the Sudwala Dolomite into the eathering zone. As the water table fluctuated with changes in the topography or climate, acidic ground matter found its way into the cracks in the dolomite and slowly but persistently dissolved the surrounding rock. A series of underground chambers eventually formed in the dolomite, the rock being carried away in solution by the water as it seeped out, or occasionally found an escape route and flowed away, leaving the chamber to fill again when the escape route became blocked by a rock fall or some obstruction. The chambers which evolved were not originally connected. Rather they resembled a sequence of underground chambers/reservoirs constantly enlarging their capacity as water seeped away and was replaced by water capable of dissolving and holding in solution more limestone. Then again an upheaval occurred, the water table dropped and change again took place. The underground reservoirs found their water steadily seeping away leaving nothing substantial to immediately replace it. The caves are estimated to be about 240 million years old and are the oldest known caves in the world.

HOW THE CALCIUM FORMATIONS ARE FORMED
As rain water seeps through plant matter, it absorbs a quantity of CO2 resulting in the formation of Carbonic acid. The carbonic acid seeps through the dolomite and picks up calcium carbonate in a solid form. It now forms an easy soluble calcium bicarbonate. It trickles down from the ceiling of the cave. Dripping from the ceiling, the water encounters an atmosphere far less rich in CO2 than the overlying sediments. Natures pre-disposition to maintain a balance induces a CO2 transfer from the water into the air. The acidity of the water drops and bicarbonate emerges from the solution as solid calcium carbonate particles which are then shed by the water. As each drop of water emerges from the ceiling its calcium content is shed and forms a ring around the circumference of the drop. The nucleus of pure water then falls, leaving behind the calcite ring. The sequence is repeated and the rings build up creating a hollow tube. As the formation develops, the centre tends to fill and the deposition continues on the outside, eventually forming a stalactite. If the dripping is too rapid for deposition, or the water contains more calcium-carbonate than can immediately be shed, It carries the surplus down to the floor of the chamber, forming a stalagmite, often with a saucer-shaped hollow known as a splash cup, at the tip. Curtains and walls of stalactites and stalagmites can develop if the water drips along the length of a crack in the ceiling. The growth rate for a stalactite at the Sudwala Caves is approximately 2,5cm in a hundred years. As regards calcium structures there are several main ones to keep an eye out for, such as 1) "The lowveld rocket, " a stalactite stalagmite column, approximately 150 million years old; 2) "The screaming monster", approximately 160 million years old; 3)"Samsons pillar, approximately 200 million years old. The age of these formations are geologically determined by the "Rhebedium Stronptium" test, which measures the radio active decay of formations.

FOSSILS
In the Pre-cambrian, all the early animals were soft bodied and thus did not fossilize well at all. However there are primitive plant fossils called "collenia" to be viewed in the Sudwala caves. They were a type of blue-green algae that used to float on the ocean. They were tubular shaped and approximately 2 m in length. It was one of the first oxygen producing plants that produced oxygen safe enough for us to breath. It dates back 2000 million years when these plants were formed. It got compacted in the rock, because at high tide sand and silt would get washed over it and get caught up in it, another layer would grow and the same process would occur.