Ototoka Beach.

These cliffs are famous for recording changes in sea water depth associated with ice age cycles. During cold periods, ice built up in the polar regions and sea level went down by as much as 130m. Sedimentary rocks were deposited here that indicate a shallow water environment. In warm periods, the sea level went up and deep water sediments were deposited. The land has been slowly uplifted to reveal the sediments in their present position.
The cliffs to the left of the path (looking down) are a good place to investigate. From the path or the beach you might be able to identify three different sequences in the cliff. The lowest ( known as the Maxwell Group) is mainly sandstone and mudstone with thin bands of conglomerate, lignite (soft brownish black coal) and some pale volcanic ash. Above that, is the Butler Shell Conglomerate, a more rough textured, irregular sequence with lots of white shell fossils about two thirds up the cliff. On top of this are orange coloured younger rocks of the Rapanui Formation, underneath sand dunes at the top.

Fossils can be found in the boulders at the bottom of the cliff, and they might include bivalves, snails, occasional sea urchins (kina) and trace fossils (tracks and burrows). Very rare whale and dolphin fossil bones have been found here in the past. (If you make such a discovery you should record its exact location and inform a museum, a university geology department or GNS Science)
If you look carefully at the middle layer (known as the Butlers Shell Conglomerate) you can see a complete sea level cycle represented from coastal river plains at the bottom surface to sea floor sand in the middle and back to coastal river plain again at the top.