BY E. C. ANDREWS. 509 



to fiercely scour its narrow channel. At the fiord or Sound 

 mouth, where the gravitative thrusts due to convergence and 

 rapid fall had been greatly expended, the depth of the rock basin 

 is quite insignificant as compared with the depths occurring near 

 the convergence of Harrison Cove, the Cleddau and Arthur 

 Canons. Again, the sides of the Sound are undercut; spurs have 

 been removed; lateral valley mouths have been removed so as to 

 leave the streams " hung " up (or perched) hundreds, or even 

 thousands, of feet above the main waterway; and the cliffs of the 

 Sound facing the canon convergences are undercut to an amazing 

 extent. Now all this may be seen, on a small scale, along a 

 disused road, where the ruts are occupied entirely by storm 

 waters. Here, at rut convergences, and at local steeps, deep 

 basins with reversed grades lower down stream are well seen, and, 

 moreover, such basins have steep bordering spurless walls. 



No topographer, in fact no casual student of geography who has 

 lived in a nonglaciated area, could, moreover, mistake these New 

 Zealand canons for stream-developed valleys. The enormous 

 undercut walls, the planation of spurs, the great rock basins with 

 reversed grades, the wealth of cirques, the hanging valleys, all point 

 indisputably to one fact, viz., that whatever agent imposed these 

 plateau forms on the landscape, such agent had occupied all, or 

 at least the greater portions, of the canons.* For the forms, gigantic 

 as they are, show the one form; the slopes are orderly and con- 

 tinuous, and are such as one observes along a stream valley if 

 attention be directed only to that portion occupied by a great flood. 

 Magnify the river flood channel to Brobdingnagian proportions 

 and we have a New Zealand canon with its associated lakes or 

 Sounds. Nor can we seek to explain the peculiar depths of the 

 Sounds by calling in postglacial subsidence, and thus minimise the 

 effects of gravitative thrusts in acting to points deeply below base- 

 level. The tale of moderate subsidence is certainly told, for 

 postglacial time, all round New Zealand and East Australia, 



* For magnificent illustrations of these contours, see figs. 1, 2 and 3 in 

 W. M. Davis ( ). 



