Drotsky's Cavern
(also knowned as Gcwihaba, much harder to
pronounce!)
It is a site adminstrated by the National museum of
Botswana - it's a cavern, but it's very hard to access: 4x4
only.
There is however Guides available.
Gcwihaba Caverns is a huge system of
dolomite caves, located in a low outcrop of rock in the dry
northwestern Kalahari. Its only accessible with a 4WD. There are
limited facilities at the cave, so take care about the necessary
equipment. Enough to eat and drink for several days, wellingtons to
wade through bat droppings, two electric torches and plenty back-up
batteries are a must. The trip will take at least three days.
Camping is allowed.
This is not a tourist cave, although it is listed in numerous
tourist directories and guidebooks like Lonely Planet. We would not
have listed this cave, if it was not already listed on numerous
other pages. So the main purpose of this page is to warn (again)
about the dangers of spelunking trips. A visit should be planned
with much care, visitors should have some caving experience. And by
the way: you might get informed about histoplasmosis before you
visit the cave.
Several Maun safari companies organize trips which include Gcwihaba
Caverns. So the safest way to visit them is on such a safari with a
guide. (Guides available at campsite)
Gcwihaba Caverns has two entrances. The cave is mostly horizontal,
but there are some steep precipices, as it has two levels. The
noteworthy stalagmites reach 10m in height. The cave is inhabited
by a large population of bats.
The cave was long known to the local !Kung people. They named it
Gcwihaba which means "the hyena's lair" in !Kung. They first showed
the cave to a European, Martinus Drotsky, in the mid 1930s.
A strange story about the cave tells about a late 19th century
treasure which is said to be hidden somewhere in the caves. The
fabulously wealthy founder of Ghanzi, Hendrik Matthys van Zyl, is
said to have stashed a portion of his fortune here.
More info:
The forming of karst caves is very complicated and it is still a
topic of geological research. But some basic aspects are very
simple: water containing carbon dioxide CO2 is able to dissolve
limestone.
Unlike with salt and gypsum, water is not able to dissolve
limestone without a little help. And this helper is carbon dioxide
CO2. Carbon dioxide is a very common gas, you know it from
sparkling water, softdrinks, and beer. They all contain it, it
makes them bubbling. Natural water also contains CO2, but much much
less, as it is normally not bubbling. Just fill some water in a
bottle and after some hours you will see small gas bubbles at the
glas of the bottle.
Carbon dioxide is in the the air, about 0.03% of our atmosphere is
this gas. Animals and humans breathe air, consume (burn) the oxygen
and exhale carbon dioxide. Many carbon dioxide is produced by
biologic processes in the soil. When the rain water falls, it first
absorbs some carbon dioxide from the atmosphere, but then, oozing
through the soil, it absorbs much more biogene CO2.
In the water, the CO2 breaks up in two pieces, thus producing a
(very weak) acid:
CO2 + H20=H2CO3=H+ + HCO3-
When
this water gets in contact with limestone, the acid solutes the
limestone.
H+ + HCO3- + CaCO3=Ca++ + 2 HCO3
This happens on the rock surface, just at the border between rock
and soil. But when the limestone, which is originally water proof,
contains cracks produced by tectonic forces - which is very common
- the water oozes into the rock and starts to widen the cracks and
solute caves inside the layers.
With the small amount of CO2, the amount of soluted limestone is
very small and it takes several ten thousand years or more to form
a cave.
The limestone in the spring water in karst areas is very common and
well known to the people living in those areas. If you heat this
water (e.g. for making coffee, in the washing machine,...) the CO2
escapes and the limestone gets solid again. This process is similar
to the forming of many speleothems in caves, like drip
stones.
More info:
http://thewhitefam.com/adventures/botswana/gchihaba.htm
To log this Earth Cache, you have to submit the
following by email.
1. Picture of you and GPS at entrance or Info
board. You can upload your picture.
2. What kind of rock is the cave?
3. What is the classification of the cave?
4. How do you think this cave was formed.