Geologist Heather Nicholson stands in front of greywacke outcrops on Waiheke Island, near Auckland. In 1953 she wrote her master’s thesis on the island’s geology and in 2003, exactly 50 years later, she submitted her PhD thesis with the title, ‘The New Zealand greywackes: a study of changing geological concepts to 1985’.
In the sound clip she talks about the way the term greywacke has been used in New Zealand.
Transcript
The name greywacke comes from a German name for a type of hard old grey sandstone. In New Zealand, the greywackes have become a useful term for a set of grey sandstones, mudstones with cherts and pillow lavas. Most of the South Island schists are metamorphosed greywackes. The greywackes, with the schists, make up New Zealand's most important rock as they occupy quarter of New Zealand's land surface, inform the Southern Alps, the North Island main ranges and the hills and islands of Auckland and North Auckland. Moreover, all the younger Cretaceous and Tertiary rocks are plastered onto a hidden greywacke basement. As a rule of thumb, if a rock is hard, grey and old looking it's greywacke.
Te whakamahi i tēnei tūemi
Private collection
Sound file courtesy of Simon Nathan
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