A fairy chimney (also called a hoodoo, tent rock, or earth pyramid) is a tall, thin spire of rock that protrudes from the bottom of a badland. Fairy chimney’s typically consist of relatively soft rocks topped by harder, less erodible rock/stone that protects each column from the elements. In Turkey they generally form within sedimentary rock and volcanic rock formations. The most famous Turkeys examples are found in Cappadocia but also Kula Geo-park harbors nice examples of fairy chimneys.
Fairy chimneys typically form in areas where a thick layer of a relatively soft rock, such as mudstone, poorly cemented sandstone or tuff (consolidated volcanic ash), is covered by a thin layer of hard rock, such as well-cemented sandstone, limestone or basalt. Sometimes these sequences alternate several times. These protective capstones protect the underlying soft and easily erodible rock from direct rain erosion. Over time, cracks in the resistant layer allow the much softer rock beneath to be eroded and washed away. The spacing and size of fairy chimneys is therefore typically related to the fracture patterns and density of the overlying cap rock. Fairy chimneys form where a cap of the resistant layer remains, and protects a ridge and later a cone of the underlying softer layer from erosion. In the figure below these different stages (from plateau to fin to fairy chimney (hoodoo) of development are illustrated. The heavy cap pressing downwards gives the pedestal of the fairy chimney its strength to resist erosion.
The Fairy chimneys in the Kula Geo-park are formed by a combination of surface water erosion, splash erosion and tunnel erosion (piping). The typical cap rocks are either cemented permeable sand stones or basalt boulders. The soft underlying rocks are often poorly consolidated impermeable sandy-clay lacustrine Miocene sediments of the Miocene Ahmetler formation. These often olive-greyish sediments are susceptible for splash erosion causing crust formation under direct rain drop impact causing surface run-off. This run-off will flow along the edge following the cracks of the fracture pattern. This causes steep narrow gullies. The contrasting permeability’s within the Ahmetler formation also causes preferential water flow true the more highly permeable layers at the contact with the underlying impermeable poorly sorted sandy-clay units. In strongly dissected badlands the steep relief gradients along the plateau edge trigger the process of piping which causes tunnel erosion causing gaps or windows in the soft rock. The collapse features of these tunnels contribute to the formation of isolated fairy chimneys (hoodoo’s).
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