Mackenzie Country: the Mackenzie basin in South Canterbury, New Zealand. An elliptical intermontane basin located in Mackenzie and Waitaki districts; about 100 km long N-S, and about 45 km wide E-W. The Southern Alps constitute its western edge. Named for James McKenzie a notable Scottish sheep thief (not many places get named after stealers of sheep). Lakes Ohau, Pukaki, Alexandrina and Tekapo lie within the Mackenzie basin, as do the artificial hydroelectric lakes of Ruataniwa, Benmore and Aviemore.
John Hardcastle considers the Mackenzie lakes on p.53 of his 'Notes on the Geology of South Canterbury'- in particular he looks at the two large lakes of Pukaki and Tekapo. These are large glacial lakes impounded by morainic dams. The moraines show interesting differences:
"A cursory examination of the Tekapo and Pukaki dams shows that they were not (blog emphasis) built up in the same manner or under the same conditions. Both were undoubtedly glacier-built, but while the Pukaki dam would be recognised as glacial anywhere, the Tekapo dam, were it not for its relation to the lake, its irregularity of surface, some moraine blocks and some patches of glacier silt upon its surface, would not be recognized as glacial. Both dams were cut down into by the rivers that drain the lakes, and the cliffs of the Pukaki show a large proportion of angular material, small and large (but with no large moraine blocks), generally showing some horizontal stratification, and all densely compacted with glacier silt. The Tekapo sections, on the other hand, show only well rounded material , evidently water laid, and not compacted with silt; containing little or no silt in fact. It is an important fact too that where the river leaves the steep and high cliffs of the dam for the lower plain, the older red gravel formation comes up into view.
The total quantity of material brought down from the mountains and piled up in these dams is enormous. The Pukaki dam is much the larger of the two, but the smaller Tekapo dam is so large as to imply the operation of frost in the Alps, and the transport by ice and water for many thousands of years."
John Hardcastle considers the Mackenzie lakes on p.53 of his 'Notes on the Geology of South Canterbury'- in particular he looks at the two large lakes of Pukaki and Tekapo. These are large glacial lakes impounded by morainic dams. The moraines show interesting differences:
"A cursory examination of the Tekapo and Pukaki dams shows that they were not (blog emphasis) built up in the same manner or under the same conditions. Both were undoubtedly glacier-built, but while the Pukaki dam would be recognised as glacial anywhere, the Tekapo dam, were it not for its relation to the lake, its irregularity of surface, some moraine blocks and some patches of glacier silt upon its surface, would not be recognized as glacial. Both dams were cut down into by the rivers that drain the lakes, and the cliffs of the Pukaki show a large proportion of angular material, small and large (but with no large moraine blocks), generally showing some horizontal stratification, and all densely compacted with glacier silt. The Tekapo sections, on the other hand, show only well rounded material , evidently water laid, and not compacted with silt; containing little or no silt in fact. It is an important fact too that where the river leaves the steep and high cliffs of the dam for the lower plain, the older red gravel formation comes up into view.
The total quantity of material brought down from the mountains and piled up in these dams is enormous. The Pukaki dam is much the larger of the two, but the smaller Tekapo dam is so large as to imply the operation of frost in the Alps, and the transport by ice and water for many thousands of years."
