A question: Why are the Canterbury Plains so flat? Professor Hutton argued that it was due to the action of the sea.
John Hardcastle wrote on the Canterbury Plains at some length; the southern plains push down into his region of South Canterbury.
"King Frost resumed his reign over Southern New Zealand. Once more the action of severe frosts in the mountains caused the rivers to be overladen with shingle, and a new set of fans was spread out over the old red gravel plain, where this had not been ridged up into hills and downs above the reach of rivers. The fans thus laid down... form the plains of today, with the connected level fillings of wide mountain valleys."
"The most remarkable feature of the Canterbury plains, I think, is the smoothness of their surface. There is nothing in our experience of river action today to explain that smoothness, which, even where the material is a coarse shingle, as on the upper Rangitata plain, required no pick and shovel work to make a track to drive a coach over. 'Old riverbeds' have not this smoothness, and the Mackenzie plain has quite a mottled appearance from the unevenness of its surface. The plains were undoubtedly laid down by rivers, but only a great sweeping rush of water could have smoothed out the current corrugations so completely. Was this a result of the Great Thaw? I think not."
John Hardcastle wrote on the Canterbury Plains at some length; the southern plains push down into his region of South Canterbury.
"King Frost resumed his reign over Southern New Zealand. Once more the action of severe frosts in the mountains caused the rivers to be overladen with shingle, and a new set of fans was spread out over the old red gravel plain, where this had not been ridged up into hills and downs above the reach of rivers. The fans thus laid down... form the plains of today, with the connected level fillings of wide mountain valleys."
"The most remarkable feature of the Canterbury plains, I think, is the smoothness of their surface. There is nothing in our experience of river action today to explain that smoothness, which, even where the material is a coarse shingle, as on the upper Rangitata plain, required no pick and shovel work to make a track to drive a coach over. 'Old riverbeds' have not this smoothness, and the Mackenzie plain has quite a mottled appearance from the unevenness of its surface. The plains were undoubtedly laid down by rivers, but only a great sweeping rush of water could have smoothed out the current corrugations so completely. Was this a result of the Great Thaw? I think not."
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