35. Karst Processes and Landforms

Photo 59: Maligne Canyon, Jasper national park, Alberta. 2011-05-19

Karst

This geographical feature is named after the Kras Mountain range in Slovenia. Karst landscapes are distinctive, associated with underground chemical weathering and erosion. So it is water that ‘eats’ away rock, particularly soluble limestone bedrock; it is the chemical process and not the frictional process that is most significant in Karst erosion. In the post on Unit 23, I explained that limestone is a sedimentary rock, i.e. compressed and cemented sediment. Photo 59 of the Maligne Canyon near Jasper, Alberta, is a good example of Karst at work.

Photo 60: Maligne canyon, dried up canyon branch. 2011-05-18

Maligne Canyon

Maligne canyon is an active Karst system with open and closed cave systems. The erosion rate is less than 1 mm per year. Maligne canyon is millions of years old and has served as a river underneath multiple glaciers. Photo 60 shows that the canyon is not static: this passageway was once part of the canyon's water stream, but now it is dried up because the water has taken a different route. The sides of the passageway are beautifully eroded.

The canyon has been formed by various processes:

·         Biological activity like tries growing on the side of the canyon help to break down the rock sides.

·         Mechanical weathering causes rock to crack due to temperature changes in the rock.

·         Dissolving of the limestone rock in the canyon is due to water flow (karst).

·         Frost shattering occurs when water in rock-cracks freezes and expands.

·         Corrasion is the erosion of rock by means of sand and gravel, which grinds away rock.

[photo removed]

Photo 61: Karst cave near Cancun, Mexico. 2008-12-18

World-wide Karst systems

Karst systems in the Alpine areas are located at very high altitudes and form deep cave systems. Karst systems in the temperate regions have a mix of surface streams and underground streams as well as cave networks, like those in Slovenia. Tropical karst develops faster and has larger features due to the higher levels of rainfall in the tropical climate regions. Caribbean karst is found in flat areas and contains underground springs and large caves. Photo 61 shows the inside of one of those Caribbean caves. The water in this cave is fed by an underground cave-river system and probably also underground springs.

Photo 62: Sinkhole at Buffalo Jump, Alberta. 2011-05-12

Sinkhole

I have quite a few images for this unit. One other Karst feature I would like to discuss is the sinkhole. The temperate Karst system steams have the characteristic of disappearing into the Earth. Photo 62 shows a dried-up sink hole at Buffalo Jump, Alberta. These sinkholes are sometimes also referred to as swallow holes.