Story: Rock, limestone and clay

Breakwater blocks, Wellington Harbour

Breakwater blocks, Wellington Harbour

These large blocks of rock are known as rip rap. They act as a breakwater and are used to protect the boats in Seaview Marina from large waves. The dolomite rocks from Golden Bay were barged across Cook Strait to Wellington, which lacks suitable rocks – the region’s greywacke is generally too shattered to form large blocks. Rip rap is also used as armour on earth dams (to stop waves eroding the dam) and to stop rivers eroding river banks around bridge supports.

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Photograph by Simon Nathan

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How to cite this page:

Carl Walrond, 'Rock, limestone and clay - Cement, marble and dolomite', Te Ara - the Encyclopedia of New Zealand, (accessed 14 April 2024)

Story by Carl Walrond, published 12 Jun 2006