The exposed Basalt here is just a small part of a large basalt flow that underlies Burnie, but is the only site in the city that has columns. These Basalt columns, particularly those at the western end of the rock face near the apartments, are regarded as being close to perfect in their hexagonal shape. In addition, the transverse cracks through the columns, dividing them into stacked segments, form special curved "ball and socket" joints. However, the columns to the eastern end are more distorted, and depart from the vertical. This area is likely to be the feeder where the lava was extruded from a fault. This irregular area is the subject of this Earthcache.
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Question 1. Describe the appearance of the non-vertical columns to the left of the regular columns. Ignore the area even further left where the rock is extremely distorted. Look at both the shape of the columns themselves, and any patterns in the transverse cracks. What do these shapes/patterns resemble?
Question 2. Further left along the rock face, in the area of extreme distortion, and about 3m from the bench seat, is a large section of rock about a metre high and close to ground level, which has had its outer face broken off, presumably when the quarry was active, exposing its internal structure. Describe the appearance and shape of this internal structure, and any visible patterns.
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