Popular Science Monthly/Volume 65/August 1904/The Lakes of New Zealand

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THE LAKES OF NEW ZEALAND.[1]
By KEITH LUCAS.

IT is difficult to make general statements which will sum up any points in the morphology of the lakes of New Zealand. This difficulty arises in the main from the strange heterogeneity of the lake basins. It would be hard, for example, to find any points of resemblance between two lakes such as Taupo and Wakatipu. In the latter the lake-basin seems to be an integral part of the surrounding country; its slopes continue the slopes of the mountain-sides. It is a mountain valley filled with water, and if it were drained dry it would scarcely appear in any way remarkable. Contrast with this the basin of Taupo. It is a trough abruptly sunk in a country which seems wholly unprepared to receive it. The perpendicular cliffs which form its western shore drop suddenly down from among hills whose slopes are comparatively gentle; in one place the cliff even forms a clean section through a large hill, cutting it from base to summit with a perpendicular face over 1,000 feet in height.

In their relations to the surrounding country, Manapouri may be classed with Wakatipu, and Rotoiti with Taupo. In the former group there is a correspondence between the position of the deepest water and the gradient of the land in the immediate nighborhood; in the latter group no such relations can be traced. In Wakatipu the greatest heights combined with the steepest gradients are those of the Remarkables and Cecil peak, and between these the deepest water lies. In Manapouri the same conditions are fulfilled by the Cathedral peaks and Cone peak. The existence of this relation indicates a rough correspondence in type between these two southern lakes and such familiar types as the lakes of the English Lake District.

A further point of similarity between Wakatipu and Manapouri is the presence in each of a large flat area where the water is deepest. This peculiarity of form is not to be confused with the tank-like form of Taupo. In the former, sloping sides lead down to a level floor, which marks the limit of depth; in the latter, perpendicular sides lead to a level floor, beyond which there is a further slope to the deepest point. In Lake Taupo, the steepest gradient leading to the highest point is found at Karangahape, on the western shore, but the deepest water lies in the northeast part of the lake. In Rotoiti there is a similar
 
PSM V65 D375 Walter and cecil peaks seen from queenston bay.png
Walter Peak, and part of Cecil Peak (on the extreme left), seen from Queenstown Bay, Lake Wakatipu.
 
PSM V65 D375 Lake manapouri and the cathedral peaks.png
Lake Manapouri, Looking north-west from the mouth of Hope Arm. Pomona Island is seen on the left, and beyond it lie the Cathedral Peaks.
 

lack of correspondence between Matawhara, at the east end of the lake, and the deep water which lies some distance to the west of it.

The two lakes Taupo and Rotoiti have in common a tank-like form of basin. It is also possible that a relation between the two may be indicated by the presence in each of isolated banks or shoals. Examples of such shoals are found in the west end of Rotoiti, and in Taupo between Karangahape and the island Motutaiko.

The remaining lakes form a very heterogeneous lot. Kotorua is a saucer-like depression, a mere continuation of the whole catchment basin in which it lies, regular in its outline and in its subaqueous slopes. It can not be compared to the more abrupt and tank-like lakes among which it lies, though it may possibly have with them a common origin in subsidence, similar but less violent.

PSM V65 D376 Lake wakatipu and the remarkables.png

The Remarkables, Lake Wakatipu. In the foreground is seen the Frankton Arm.

Waikare and Whangape are so shallow as to rank rather with swamps than with lakes, in spite of their considerable area. The interest of the former lies chiefly in its peculiar relation to the Waikato river, a relation which enables it to reduce the harmful effects of floods, though not lying on the river's actual course.

  1. Conclusion of an article in the Geographical Magazine for June.