9 SURFACE FEATURES IN LIMESTONE OR KARST AREAS

9 SURFACE FEATURES IN LIMESTONE OR KARST AREAS

Grikes and Clints

Clints – Blocks of limestone rock left standing when water infiltrates through the limestone rocks widening and deepening the joints.

Grikes – Deep groves or gullies formed when rainwater infiltrates through limestone rocks widening the joints by solution.




Swallow/Sink Holes

Deep vertical holes formed on limestone rocks when solution extends the grikes.

Referred to as swallow/sinkholes because surface runoff or river water may disappear through them as a waterfall and come out of the ground as a vauclusian spring further downhill.

A vertical shaft from the surface of the sinkhole down into the ground is called ponor.

Dry Valley

Steep valleys with no permanent streams on limestone surface at the section between the swallow hole and where the river emerges.

Karst Window




A small outlet to the surface from a cavern formed when continuous carbonation at the surface causes the roof of the cave to collapse.

Limestone Gorge

Deep steep-sided river valley in limestone rocks formed when the swallowed river causes the solution to continue underground causing the roof of the underground watercourse to collapse.

Karst Bridge

Small section left joining the roof between the karst window and gorge.

Dolines




Elliptical hollow with gently sloping sides on the surface of a limestone region formed when several swallow holes collapse and merge.

Uvala

Depression which may be as wide as 1 km in diameter formed on the surface of limestone regions when several dolines collapse and merge.

Polje

Largest, shallow, elliptical and flat-floored depressions on a limestone region formed when several uvulas collapse and merge.

May become a temporary lake or may be covered by a marsh.

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