38 Transactions. 



General Physiography. (See map.) 



The district under special consideration lies to the north-east and north 

 of Lake Tekapo, which occupies the most easterly of the three main valleys 

 leading from the highest section of the Southern Alps out on to the sloping- 

 plain region of the Mackenzie country, which owes its formation largely to 

 the aggrading action of the great rivers which formerly flowed from the 

 fronts of glaciers issuing from those valleys. The basin is bounded on the 

 east by the Two Thumb Range, which branches off the main divide of the 

 Southern Alps in the vicinity of McClure Peak (8,192 ft.), and runs south 

 without a break until it reaches the Ashwick Saddle and Burke's Pass, whence 

 it continues southward as the Hunters Hills. The range is highest at its 

 northern end, where it is dominated by the great mass of Mount d'Archiac 

 (9,279 ft.) ; but high peaks are found farther south, such as Mount 

 Chevalier (7,910 ft.), the Thumbs (8,338 ft.), and Fox's Peak (7,604 ft.) ; 

 while for long distances it is over 7,000 ft., and rarely sinks below 6,000 ft. 

 It thus forms a thoroughly effective divide between the north-eastern part 

 of the Mackenzie basin and the valleys of the Rangitata and Opihi, which 

 lie to the east. From this range important ridges stretch down towards 

 Lake Tekapo, such as the Sibbald Range, which divides the Godley Valley 

 from that of the Macaulay, with Mounts Sibbald (9,181 ft.) and Erebus 

 as its leading peaks, and the Richmond Range, which reaches south-west 

 towards the middle of the eastern shore of Lake Tekapo. To the south 

 of the Macaulay lies Mount Gerald,, which, though not very high, is a note- 

 worthy feature of the landscape. 



The chief rivers feeding the lake are the Godley and the Macaulay, 

 the former rising in the main divide and the latter draining the country 

 between the Sibbald Range and the Two Thumb Range. On the western 

 side of the lake the chief streams are the Cass River and Mistake River ; 

 while on the eastern side the most important streams are Coal River and 

 Boundary Creek, both of which flow first of all south-west and then west. 

 The former follows along the northern flank of the Richmond Range and 

 enters the lake at its extreme north-eastern corner, while the latter follows 

 along the southern side of the range and enters the lake about the middle 

 of the eastern shore. 



The surface of Lake Tekapo is 2,321 ft. above sea-level, and it is there- 

 fore the highest of the great lakes of New Zealand. It has a length of 

 about fifteen miles and a breadth of about three and a half in its widest 

 part, and is somewhat quadrangular in shape. Its general surroundings 

 are monotonous, and the country is now treeless except for the plantations 

 in the neighbourhood of station-homesteads. The shores, too, are flat 

 and wanting in bold features Only on the western side, in the vicinity 

 of Mount John and the Mistake Range, do hills closely approach the lake ; 

 and in these cases they rise precipitously from the water's edge, and exhibit 

 all the features of valley- walls whose bases have been sapped back by lateral 

 glacial erosion. 



On the eastern side the country rises gradually from just above lake- 

 level to the foot of the spurs from the Two Thumb Range, such as Mount 

 Gerald and the Richmond Range ; and the profile of these slopes is 

 evidently carried down to the bed of the lake, so that it has not the form 

 of a true glacial trough, but rather of a widely open groove or depression. 

 The lake is thus somewhat shallow— 387 ft. was the maximum depth 

 obtained by Ayson — and two small ice-scoured islands with outlying reefs 

 near the lower end of the lake emphasize the fact that the solid bottom 

 does not lie far below a large area of the water. 



