Airedale Reef

Accessibility: EASY
Fossil forest at Airedale Reef, J.Thomson / GNS Science
A fossil forest extends along the shore platform with many fallen trunks, and tree stumps in life position within a peaty soil. . The nearby cliff shows a deposit overlying the fossil forest, originating from Mt Taranaki, over 40km distant
Sea cliff at Airedale Reef, J.Thomson / GNS Science
The fossil forest that is exposed on the reef was living towards the end of a warm interglacial period, and was a podocarp forest with rimu and tree ferns. Overlying the fossil forest (best seen in the nearby cliff) is a 4m+ thick layer of unsorted boulders and mud that contains occasional wood pieces. This layer is thought to be part of a huge debris avalanche that originated as a massive collapse of the Mt Taranaki cone about 40 kilometres away, releasing over 3.6 cubic kilometres of rock that spread over an area of more than 250 square kilometres of the Taranaki plain. Above the debris avalanche, there are several pale and orange soil layers that were deposited as the climate entered the cooler phase of the last ice age.
Fossil forest at Airedale Reef, J.Thomson / GNS Science
Explore the variety of large tree trunks and stumps scattered across the reef. Many of them are in life position, within a bed of dark peat. See if you can find seeds in the peaty soil around the tree stumps. Also explore the cliff section where you can see an olive green layer of dune sands in places at the very base of the cliff, with a thick layer of peat above it. This dark carbon rich layer with branches and roots is the same as the forest layer that extends across the reef nearby. Within it you can see scattered particles of sharp glassy crystals. This is volcanic ash that must have been erupted when the forest was alive. The next layer above the carbon rich layer is a 4 metre thick unsorted mixture of large and small particles that include boulders of volcanic rocks and occasional wood fragments. This thick conglomerate lies directly on the fossil forest layer and represents one of several massive collapses of Mt Taranaki that have occurred since it formed about 130,000 years ago. Try to work out if you think that the debris avalanche actually killed the forest, or if it was already killed off by another cause before the avalanche occurred.

Park at the end of the road (Howard Street) on the eastern side of the Waitara river mouth It is a 25 minute walk along the beach from the parking area.

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Accessibility: EASY

The reef is best visited at low tide.

Sedimentary Fossils
Geological Age
Pleistocene, about 100 000 years old.
Zealandia Evolution Sequence
Pākihi Supergoup: 5 million years ago – present
Check out this video about the erosion processes of Taranaki Volcano, and the resulting sediments in the surrounding area: (9m 20s) Geological QMap and report for Taranaki: