Ladies Bay is a secluded beach, below steep cliffs, on the headland west of the lookout over Achilles point.
Some volcanic rocks can be found on the beach below – some fragments ejected from deep in the earth, or blocks of tuff ring that were once perched on top of the cliff.
The rocky shoreline overlooks the Waitemata Harbour which itself occupies a drowned valley system cut in marine sediments of Miocene Age (15–25 million years ago).
[4] The concretions that can be easily seen, are formed by the action of ground water with dissolved minerals (mainly calcium carbonate of which limestone is made) percolating through the layers.
[2]: 231–3 The presence of overlying Rotoehu tephra on a drill ore means the volcano last erupted more than 45,000 years ago, but the age is unclear within a wide range.
This has resulted in the discovery that a distinctive lithic clast in the tuff that contained shell fragments was strong evidence that the erupted magma traversed the eastern border of the ophiolitic Dun Mountain–Maitai terrane.