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In this lesson we are going to discuss about the surface features of limestone areas

Answer Text:
Surface Features in Limestone Areas
a) 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.

b) Swallow/Sink Holes
- Deep vertical holes formed on limestone rocks when solution extends the grikes.
- Referred to as swallow/sink holes 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.
- Vertical shaft from the surface of the sink hole down into the ground is called ponor.

c) Dry Valley
- Steep valleys with no permanent streams on limestone surface at the section between the swallow hole and where the river emerges.
d) Karst Window
- Small outlet to the surface from a cavern formed when continuous carbonation at the surface causes the roof of the cave to collapse.
e) Limestone Gorge
- Deep steep sided river valley in limestone rocks formed when the swallowed river causes solution to continue underground causing the roof
of underground water course to collapse.
f) Karst Bridge
- Small section left joining the roof between the karst window and gorge.
g) Dolines
- Elliptical hollow with gently sloping sides on the surface of a limestone region formed when several swallow holes
collapse and merge.

h) 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.

i) Polje
- Largest, shallow, elliptical and flat floored depressions on a limestone region formed when several uvalas collapse and merge.
- May become a temporary lake or may be covered by a marsh.