Notes on a Visit to Macquarie Island Journal Paper
- Author
- Hamilton, A.
- Year
- 1895
- Journal / Source
- Transactions of the New Zealand Institute
- Publisher / Organisation
- New Zealand Institute
- Volume
- 27
- Pages
- 559-578
- Keywords
- beaches, sand, Waitakere Ranges, heavy minerals, grain size, littoral drift, longshore currents, Taupo Volcanic Zone, sediments, iron-rich composition
- Summary
- Heavy mineral rich beach sands of the Tasman Sea coast of the Waitakere Ranges, west of Auckland City, include major minerals plagioclase, augite, titanomagnetite, and quartz, with minor ilmenite, hypersthene, hornblende, biotite, and potassium feldspar, and accessory zircon and apatite. Major sources for the sands are Taupo Volcanic Zone rhyolitic volcanics, delivered via the Waikato River, and Taranaki andesitic volcanics, via the longshore drift. Longshore trends from south to north include a slight fining, a reduction in rock fragments, an increase in heavy mineral content, and a tendency for the feldspar/quartz ratio to decline. Ilmenite is a significant component; it is derived from the Taupo Volcanic Zone (not from the Waitakere Ranges as previous authors have suggested), and it increases in quantity from south
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