The narrow isthmus connecting the Tasman Peninsula to mainland Tasmania (in Australia) is covered with beautiful and rugged terrain and several unusual geological formations, among which is a peculiar erosional feature called Tessellated Pavement. This rare feature that occurs on an area of flat rock on Eaglehawk Neck looks distinctly manmade, but is in fact, formed by natural causes.
Tessellated Pavement is so called because the rocks here have fractured into polygonal blocks that appears tessellated or tiled. The flatness of the pavement is due to initial erosion by waves carrying sand and gravel, or by chemical action by sea water. The rocks which absorb sea water during high tide dry out during low tide causing salt crystals to grow and disintegrate the rocks - a process which produces shallow basins.
At Eaglehawk Neck two types of formations are seen: a pan formation and a loaf formation.
The pan formation is a series of concave depressions in the rock that typically forms beyond the edge of the seashore. This part of the pavement dries out more at low tide than the portion abutting the seashore, allowing salt crystals to develop further; the surface of the "pans" therefore erodes more quickly than the joints, resulting in increasing concavity.
The loaf formations occur on the parts of the pavement closer to the seashore, which are immersed in water for longer periods of time. These parts of the pavement do not dry out so much, reducing the level of salt crystallisation. Water, carrying abrasive sand, is typically channelled through the joints, causing them to erode faster than the rest of the pavement, leaving loaf-like structures protruding.
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