Devils Kitchen is the name given to a natural amphitheatre of high basalt cliffs bordering the Woady Yaloak River at Piggoreet. The amphitheatre has been caused by the river establishing a course through a valley filled with lava flowing from volcanoes active in the late Tertiary period. The basalt cliffs contain evidence of a number of separate lava flows that filled the valley. Directly in front of the posted co-ords you can see a number of hexagonal columns that developed during the cooling of a thick lava flow because of fractures in the molten rock. If a flow cools relatively rapidly, significant contraction forces build up. While a flow can shrink in the vertical dimension without fracturing, it can't easily accommodate shrinking in the horizontal direction unless cracks form; the extensive fracture network that develops results in the formation of columns. The topology of the lateral shapes of these columns can broadly be classed as a random cellular network. These structures are predominantly hexagonal in cross-section, but polygons with three to twelve or more sides can be observed. The size of the columns depends loosely on the rate of cooling; very rapid cooling may result in very small (<1 cm diameter) columns, while slow cooling is more likely to produce large columns.
In order to log this Earthcache you need to email me with your answers to the following questions;
Q1: How high do you estimate the cliffs in front of you to be?
Q2: What do you estimate the diameter of the central columns to be?
Q3: Turning around and looking at the eastern basalt cliffs behind you, how does the shape of the Basalt formations differ compared to the columnar cliffs?
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