The Canterbury Plains were formed from Quaternarymoraine gravels transported from the Southern Alps and deposited here during glacial periods in the late Pleistocene approximately 3 million to 10,000 years ago.[2] The alluvial gravels were then reworked as shingle fans of several of the larger rivers, notably the Waimakariri, the Rakaia, the Selwyn, and the Rangitata. Part of the Canterbury-Otago tussock grasslands, the land is suitable for moderately intensive livestock farming but is prone to droughts, especially when the prevailing wind is from the northwest. At these times, the weather phenomenon known as the Nor'west arch can be seen across much of the plain.
A major earthquake on 4 September 2010 revealed a previously unknown geological fault beneath the Canterbury Plains and created a surface rift that offset features by as much as four metres in places.[3]
Rivers
The rivers of the Canterbury Plains have a distinctive braided appearance, which differentiates this area from the plains of North Otago to the south – beyond the Waitaki, the rivers typically have narrower, well-formed channels, rather than spreading across wide shingle depressions, as in Canterbury.
↑Gage, M., (1969), 'Rocks and Landscape', in The Natural History of Canterbury, edited by Knox, G. A., Canterbury Branch of the Royal Society of New Zealand, A H & A W Reed, Wellington, p. 35.
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