42 Transactions. — MisceHaneovs, 



solution, and scrutinized closely the merits of my ex^Dlanation, it failed to 

 stand the test of that exammation. The question to be solved was the 

 following : You are, without doubt, all aware that the rivers on the Canterbury 

 Plains have the tendency to undermine their banks, consisting of loose 

 fluviatile deposits, on their left or northern side, and that they have done this 

 already so effectually that, in their lower coiu-se and for a considerable dis- 

 tance, their right or southern banks are always low, and possess scarcely any 

 terraced appearance, whilst they continue, generally to the very sea-shore, to 

 be fringed on their left banks by a high terrace or cliff. To give only one 

 instance, I wish to i^oint to the Kangitata, where the railway crosses it, and 

 where we have to descend considerably before we can reach the river-bed, 

 which, on the southern side, is only bounded by low ground. It must 

 strike even the casual observer that, whilst the left bank forms, as far as 

 the eye can reach, a high and conspicuous cliff, the right bank is so very 

 low and ill-defined that the river continually changes its course. 



With many geologists who had observed similar phenomena in other 

 countries, I had tried to explain this peculiar tendency of our rivers by 

 assuming a small oscillation of this portion of the South Island, the North 

 gradually sinking and the South rising, by which the waters of all the 

 rivers flowing through it would be thrown towards their northern banks ; 

 but when I searched for evidence all round Banks Peninsula, or at Timaru 

 and Double Corner, for this supposed partial sinking and rismg of the 

 ground, the evidence before me did not warrant such an assumption. 

 Some time ago I found in Professor von Hochstetter's excellent geological ■ 

 hand-book, " Die Erde," reference to a theory first set forth by Carl Ernst 

 von Baer, the eminent physiologist and anatomist, but who was equally 

 distinguished as a physical geographer, by which that peculiar feature of 

 our rivers is fully explained. Although von Baer could only base his 

 theory on the rivers of the northern hemisphere, and then principally 

 upon those of Eussia and Western Siberia, it will be seen that it is fully 

 borne out by our own rivers. These latter, moreover, prove the universality 

 of the phenomenon, with the exception, as von Baer prognosticated, that 

 the opposite banks of the rivers in the southern, when compared with 

 the northern hemisphere, would be affected. 



It is long ago that the observation was made on several rivers in 

 Euroi^e and Northern Asia, which are enclosed in banks of loose material, 

 that they continually and steadily try to advance towards the right, and 

 that consequently they wash away and undermine their right banks. Many 

 explanations were given, principally (as I had tried with our own rivers) by 

 assuming local changes in the level of the earth's crust ; but the generality 

 of the phenomenon made such an explanation impossible. 



