lying from N.N.E. to S.S.W., and that being directly athwart the track of the almost constant winds from the Pacific Ocean, their influence on the climate of the country may be considered as of the highest importance; for not only do they break the force of those winds, but their cool tops condense the vapours into showers that might otherwise pass over so narrow an island without parting with a drop. The height of the ridges causes the rainfall on them to take the form of snow, which lies on them during the greater part of the year; this circumstance, by accumulating over long periods, what would otherwise run off in streams as it fell, is the prime cause of the great, sudden, and at first sight, apparently inexplicable floods that characterise all the rivers that have their sources in high mountains. Change of temperature is the secondary and immediate cause; but while this is the case a flood may occur without any great or perceptible increase of temperature, for the wind, by transporting the snow to a lower altitude, occasions the same effect as a rise of temperature. It was noticed during the survey, that the snow line on the N.W. side (the windy side) of the mountain ridges was higher than on the S.E. side (the sheltered side,) thus showing that the wind is a very decided cause in producing the effects now under consideration. The flood marks on the mountain streams, more especially those running into the Te Anau and Manapouri Lakes, show a rise and fall almost incredible. The power exercised by such torrents is forcibly impressed on the attention, by an examination of their channels, immense blocks that have in the first place been disintegrated from the surrounding mountains by frost, lie in their channels, and through the never-ceasing attrition of rushing waters are being broke up into shingle and sand that is carried forward and deposited in the lakes; the mouths of the rivers all show that they are advancing into the lakes, however slowly that may be. The lakes are a very great feature in the natural history of the country, and perform a most important function in its economy. They act as regulating reservoirs to the mountain torrents already mentioned, for over their broad surface the floods find room to spread their volume, until there is time given for the accumulation to pass away in the steady flow of one river. The value of the lakes as a means of restraining such rivers as the Clutha and Waiau within safe limits, will more readily appear when it is considered that the Te Anau and Manapouri Lakes, (the two principal of the Waiau River system) alone cover 163 square miles, and that their surfaces have a rise and fall of 8 or 9 feet during the course of the year. The Clutha River, likewise has the Wakatipu, 114 square miles; the Wanaka, 75 square miles; and the Hawea, 48 square miles: altogether, 237 square miles of lake to regulate its volume. These lakes have also a rise and fall of several feet. From the data now given, it will be evident that but for the tempering influences of the Lakes, the Clutha and Waiau, in place of flowing along a well defined channel, in a perennial stream as now, would have been so fluctuating in volume that no channel could have contained them, and their valleys would have been a shingle bed to the sea—a continuation, in fact, on a grand scale, of such valleys as those of the Dart and Matukituki.

The greater extent of the Lakes at a former period is evident from the terraces that surround their present boundaries; it is plain that the Wakatipu Lake must have extended formerly over the low fertile track of country that extends east from Frankton to the Crown Ridge. The summits of Peninsula Hill, Morven Hill, and perhaps some of the lesser elevations, would then be islets. The old channel of a large river leading away from the south end of the lake, at Kingstown, is very suggestive that then the overflow of the lake passed away by it, and down the Mataura, to the sea. Examination of the valley in which this old channel lies, does not readily explain the cause of this rearrangement in nature, for no sudden upheaval has there dammed the waters of the lake back from their ancient exit: the old channel remains as distinct and as well defined as though the change had only been a thing of a few years. The waters of the lake have receded rather more than a mile in distance, and left the old channel high and dry. The very abrupt gorge through which the Kawarau (the present outlet of the lake), flows, suggests that the change has been brought about by the sudden erupting force of an earthquake opening a pass through the mountains lower than the level of the then lake; and that the present deep gutter-like channel of the Kawarau has been the subsequent slow and gradual wearing down of the channel by the rapid current that sweeps along it.

The depth of the lakes is an interesting consideration in connection with them. I had not the means of determining it; but that their depth may be reckoned by hundreds of feet, I have almost no doubt. On leaving the shore, and at the distance of a boat length or two, the bottom may be seen down through the clear water at a depth of 20 or 30 feet: then very often there is a sudden dip, and there begins the