20i Physical Geography of 



and well-defined terraces in their upper and middle courses, being simply 

 shelves cut in the solid rock along the mountain sides by a gigantic 

 glacier. These shelves in many instances are situated as high as 

 3000 feet above the present level of the valleys, and are very 

 characteristic of our alpine scenery, although I may add that the same 

 features are also amply developed in the European Alps, the 

 Himalayas of Asia, and the Eocky Mountains of Xorth America. On 

 ascending the mountains in these valleys, the size and extent of the 

 shelves become still more manifest than when travelling only along 

 the river-bed. The most westerly tributary of the "Waitakiis the Ahuriri, 

 the glacier sources of which are situated on the southern slopes of 

 Mount Huxley, the southern continuation of Mount Ward. The valley 

 of the Ahuriri is fifty-two miles long ; for twenty-seven miles it has a 

 southerly course, after which it turns gradually to the east, when, for 

 twenty-five miles it runs in that direction, joining the TTaitaki fourteen 

 miles below the junction of the Ohau river. The river-bed of the 

 Upper Ahuriri for about eight miles, is narrow and rocky, the moun- 

 tain slopes on both sides rising abruptly ; it then gradually expands, 

 but is still repeatedly crossed by large moraines, through which the 

 river has cut a narrow channel. Eourteen miles from the head of the 

 river, the valley is nearly two miles broad, and is now, for seven miles, 

 one large swamp through which the river sluggishly meanders from side 

 to side. At the lower end of this strange fen, a huge moraine crosses 

 from one side to the other, and it is at once evident to the visitor, 

 that at one time a lake must have existed above it, but which in time 

 was gradually so far filled up, that it has assumed this intermediate 

 instructive stage. There is no doubt that if the present physical con- 

 ditions now ruling in Xew Zealand, continue for a length of time, 

 the shingle deposits brought by the Ahuriri into this huge swamp will 

 gradually advance and fill it up entirely, in the same manner as the 

 lakes once lyiug in the middle courses of some of the northern alpine 

 rivers have been changed into alluvial plains, thus entirely effacing 

 such large remnants of former glacier basins. The Ahuriri, where it 

 issues from the fen, has cut a deep channel through the morainic walls, 

 below which broad alluvial plains stretch from side to side. Here the 

 river flows also in a deep bed with terraces on both sides, which, before 

 the Lindis Pass stream is reached, is confined in a deep rocky 

 channel, the alluvial deposits continuing to fill the valley, and 

 resembling in every respect, those which we meet below the great 

 moraine walls encircling the lakes in the Mackenzie Country 

 plains. 



