| Cliff
failure takes place primarily by the development of large rotational slips which
may extend well below sea level. There are about fourteen major slips along the
North coastal section. These are lubricated by groundwater during the winter when
most movement tekes place. Movement is mostly slow and progressive, but occasionally
very rapid slipping takes place. | ||
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| This
massive rotational slip at Warden Point occured in January 1989. An area of cliff-top
180 metres long by 40 metres deep dropped by about 15 metres in one night. The
woodland on the slope was originally on the same level as the cliff edge | The beach immediatly in front of the slip (an area about 200 metres long by 10 deep) was raised by up to 9 metres. It was forced up by the pressure of the cliff rotating behind it. This new low cliff took only three months to completely erode away. | |
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| This
'beach heave' near Hensbrook is associated with a rotation far back in the cliffs.
It was witnessed as it happened after a night of heavy rain. These photographs
were taken as the beach slowly raised and cracks appeared.
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