Cockpit Country in Jamaica is the type location for
cockpit karst. Cockpit Country was the name given to the area by
the British in the 17th century because it reminded them of the
then-popular cock-fighting arenas which were hot, humid and
dangerous places where men gathered to watch and bet on the
"sport". Note that cockfighting is illegal now (but is still
practised -Easter 2001- in some areas of Jamaica): the concept was
still familiar enough to aviators in the early 20th century for
them to use "cockpit" as the name for their station on an aircraft.
The word "karst" derives from 'Kras' in
Slovenia:- "a dry, waterless place". Although the Cockpit Country
receives high rainfall annually (1500mm to 2500mm), it is still
considered "waterless" because limestone acts as a sponge: surface
water is drained vertically and rapidly and each cockpit bottom
("sink") is drained by a sinkhole. (seemovie)
Don't hike without a guide! (See one group's experience)
The formation of Cockpit Country started about 12 million years ago with a faulted limestone plateau when Jamaica emerged from the sea. The plateau rose to about 600m (2000ft) above sea level, with a tilt of between 5 and 15deg to the NW. Erosion of this plateau formed the regular array of round-topped, conical hills and sinks that we know today.
There are at least two theories as to how cockpit karst forms (see movie). The "solution" theory holds that heavy tropical rainfall washing through a fissured limestone plateau over millions of years dissolved and eroded the fissures and washed the debris through the sinkholes eventually out to sea.A recent researcher measured the orientation of the faults in the area and found them to be largely aligned along three primary axes mutually at 120 degrees.
He surmises that a sinkhole forms when three faults intersect.This theory provides an explanation of the typical, regularly-spaced, round-topped, conical hills.At the top of the hill, the water moves slowly so that little erosion takes place; as the water runs down the hill, it gathers momentum and also gathers debris so that its scouring action becomes more and more pronounced. This accounts for the slope being so steep at the base. Of course, each cockpit has one or several sinkholes but there is a tendency for these to become blocked by debris.
One of the puzzles for a layman is how the bottom of each cockpit is so flat: this is because, during times of heavy rain, water also comes UP the sinkholes and floods the sink or cockpit. It is this flooding over the millenia which redistributes debris over the entire bottom of the sink.
The other "collapse" theory maintains that the formation and subsequent collapse of cave systems is the primary mechanism for cockpit karst formation. It is not generally realised that caves in limestone hills have a finite life as they migrate upwards through the hillside. This migration is caused by successive collapses of the ceiling due to the solutional effects of water percolating downwards. Obviously, every time the ceiling collapses, the ceiling gets higher and the floor is raised by the debris: so the whole chamber gets higher. Eventually the cave opens to the sky.We value your feedback and comments: