KARST LANDSCAPES - Fundamentals of Geomorphology

Geology Reference

In-Depth Information

of the inherent scientific interest of karst landscapes. At

the regional level, 121 karst areas, covering 18,441 km 2

or 14.3 per cent of the total karst, are afforded pro-

tected area status. Higher levels of protection are found

in Cuba, the Dominican Republic, and the Bahamas.

Lower levels of protection occur in Jamaica, Puerto Rico,

Trinidad, and the Netherlands Antilles, and minimal pro-

tection is established in the smaller islands. In Trinidad

and Tobago, for instance, karst forms comprise karren,

caves, springs, valley systems, and a range of sinkholes,

including an area of polygonal cockpit karst (Day and

Chenoweth 2004). Quarrying, and to a lesser degree log-

ging and agriculture, have destroyed much of the karst in

western Trinidad, whilst urban development and tourism

have added to the damage in Trinidad and in the low-

lands of western Tobago. Little of these karstlands lie

within existing protected areas.

formations or speleothems, material weathered in situ ,

and clastic sediments carried into caves and laid down

there. Speleothems are multifarious, and may be grouped

into dripstones (such as stalactites and stalagmites),

eccentric forms (such as helictites and moonmilk), and

subaqueous forms (such as rimstone pools and gours).

Agricultural practices have led to the stripping of soil

from some karst areas. The fascination of caves has pro-

duced a thriving cave tourist industry, but cave visitors

may destroy the features they come to view. Karstlands,

too, are threatened in many parts of the world and require

protection.

ESSAY QUESTIONS

1 How distinctive are karst landscapes?

2 Discuss the role of climate in karst

formation.

3 Analyse the problems of karst

management.

SUMMARY

Karst is terrain with scant surface drainage, thin and

patchy soils, closed depressions, and caves. Its distinctive

features develop on fairly pure limestones, but also occur

in evaporites and silicate rocks. It forms by the dissolution

of limestone or other soluble rocks, in conjunction

with creep, block slumps, debris slides, earthflows, soil-

falls, rockfalls, block slides, and rock slides. Fluvial and

hydrothermal processes may affect karst development.

A multitude of landforms form on limestone: karren

of many shapes and sizes, limestone pavements, pin-

nacles, karst ruins, corridors, and coastal karst features;

also, a range of closed depressions: dolines, karst win-

dows, uvalas, and polja. Cone karst is a tropical form

of karst, two varieties of which are cockpit karst and

tower karst. Labyrinth karst is an extratropical version

of tower karst. Despite a scarcity of surface drainage in

karst terrain, fluvial processes affect some karst land-

forms, including gorges, blind and half-blind valleys,

steepheads, dry valleys, meander caves, natural bridges,

and tufa and travertine deposits. Another multitude of

landforms forms within limestone in subterranean karst.

Speleogens are erosional forms in caves. They include

potholes and current-markings, rock pendants and scal-

lops. Within caves, three types of deposit are found: cave