Geo Junkets: New Zealand, North Island (Part 3)

Jesse Garnett White (USA) Kohioawa Beach and Matatā Escarpment, Putauaki Volcano and the Kawerau Geothermal Field Kohioawa Beach and Matatā escarpment. Kohioawa Beach, an uninterrupted sweep of sandy beach, dunes and wetlands, is directly below the near vertical Matatā escarpment between the towns of Otamarakau and Matatā. The escarpment gradually gains elevation to its highest point behind Matatā. Infrequently cut by active and inactive canyons, flowing streams debouche across the beach into the Bay of Plenty. Atop the escarpment are rare, mature pohutukawa, puriri and manuka, and various types of scrub and grass. Part and parcel of the Whakatane Graben, the terraced escarpment is composed of Castlecliffian marine sediments, remnants of the Aranuian Interglacial period. On the western margin of the graben near Matatā, marine sandstone and siltstone outcrops contain bivalves, gastropods, crustaceans, sponge spicules and microfossils, overlain by tuffaceous sediments, ignimbrite gravels and conglomerate (Nairn and Beanland, 1989). The coastal dune and wetland areas of the Rangitaiki Plains and Tarawera River Valley near Matatā exhibit Holocene backswamp and floodplain deposits, including levees and meander sediments associated the Awatarariki, Waimea and Waitepuru stream catchments. The catchments rise from sea level to 370m elevation and drain into the Bay of Plenty. The Awatarariki and Waitepuru wetlands were destroyed in 2005 by large, storm-induced debris flows and associated floodwaters. Waimea was largely unaffected, retaining the majority of its pre-storm event character. Matatā township was severely impacted by debris flows, with over a hundred homes and properties damaged or destroyed. Prior to the … Read More

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