Eastern Beach folded strata

BY JULIAN THOMSON (OUT THERE LEARNING)
Accessibility: EASY
Upfold or anticline in cliff, J.Thomson / GNS Science
Layers of sandstone and mudstone have been folded and much later eroded by the sea to expose their geometry.
The beds have been eroded out horizontally on the shore, J.Thomson / GNS Science
These sandstone and mudstone strata where laid down under the sea in a subsiding basin about 20,000,000 years ago. It is thought that the folding occurred when the sediments were still soft, by sliding of the sea floor. Geologists use the term anticline for an up-fold, and syncline for when the rocks are folded downwards.
Erosion of the folded rocks in the cliff and on the shore, J.Thomson / GNS Science
It is best to go at low tide so that you can walk around on the shore platform and get a close look at the layers. Because the sandstones are harder than the mudstones, they are more resistant to being eroded and stand out more visibly on the shore.
It is interesting to compare the appearance of the fold in the vertical cliff compared to the same feature being cut through horizontally by the sea washing across the beach. The fact that the layers on each side of the fold are not parallel on the shore ( they meet up in a curve) tells us that the fold is dipping gently to the north. Can you locate a syncline as well as the anticline?
Directions/Advisory

Park at the north end of Clovelly Road in Buckland's Beach.

Google Directions

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Accessibility: EASY

There is a steep staircase down to the shore. Best to visit at low tide.

Features
Sedimentary Rock Deformation
Geological Age
About 20 million years
Zealandia Evolution Sequence
Māui Supergroup (Emergence): 25 – 5 million years ago