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Stratigraphy and Petrography of North-East Otago Loess

1964; Taylor & Francis; Volume: 7; Issue: 4 Linguagem: Inglês

10.1080/00288306.1964.10428133

1175-8791

D. J. Young,

Landslides and related hazards

Abstract An extensive loess mantle up to 36 ft thick, but generally less than 15 ft thick, covers much of north-east Otago, especially on the intermediate and high-level terraces south of the Waitaki River from Duntroon to the coast, and in the vicinity of Cape Wanbrow, near Oamaru. This loess is a pale yellow, angular, poorly sorted, positively skewed, medium silt. It is composed predommantly of quartz, feldspar (andesine?), accessory muscovite, and about 4% heavy minerals. The minerals are consistent with derivation from either a greywacke or schist terrain. Both slope-wash deposits and loess are discussed, because on steeper slopes slope-wash replaces loess deposition when the climate is severe. Hence, from Livingstone, a sequence of three loesses and two slope-wash deposits are described, and an attempt is made to correlate these units with loesses at Five Forks, and Maheno. The sequence of terrace gravel, loesses, and slope-washes, with soil development at one major and one minor horizon, is interpreted as providing a record of events during and since the Penultimate Glaciation.