Wai-iti Beach North Taranaki

The rocks at Wai-iti Beach are part of the Urenui Formation and are around 5 million years old. They are mudstones, formed from mud sediments deposited in about 1000 m of water, to the west of an emerging North Island landmass that existed in the area around the present day National Park-Ohakune area. The sandstones and conglomerates we see at the northern headland at Wai-iti Beach formed within a large submarine channel that was cutting into the muds in this ancient sea. The sands and gravel represent the eroded sediments coming from the central North Island ranges (such as the Kaimanawa and Ruahine ranges) as they were being tectonically uplifted at this time. The upper parts of the coastal cliffs are made up of soft brown-coloured sands, muds and gravels and are much younger than the rocks exposed near to sea level. They are less than 125,000 years old and represent beach, dune, and old soils of the Rapanui Formation.

Sometimes, depending on the movement of sand on the beach, there are stumps and logs visible at low tide. These were forest trees growing around 7000 years ago when the area was a lowland forest, formed well above the sea level of the time. Some of the tree stumps are in growth position. Since then sea level has risen to its present level. Also look for shelly fossils and layers of white volcanic ash particles in the mudstones exposed near the headland to the south. Here also there are trace fossils - feeding traces formed by some of the organisms that were living in the ancient sea. One forms a circular pattern 20 to 80 cm in diameter and is called Zoophycos.