Marshall. — Geological Notes on South-west Otago. 497 



to account for the peculiarities of fiord depressions and the 

 valley-lakes of alpine regions. The remarks and descriptions 

 of Mr. Andrews have been found by the author to hold satis- 

 factorily for the various sounds and inland valleys visited by 

 him dm-ing the past few years. As stated in the " Geography 

 of New Zealand," the peculiarities of the valleys of the Mount 

 Cook region still occupied by glaciers reproduce in their main 

 features the pecuUar curves and mountain and valley forms 

 found in such abundance in the fiord region. The beautiful 

 illustrations in Mr. Andrews' paper depict satisfactorily the fea- 

 tures of most importance in these Sounds, with the exception 

 perhaps of those smoothed and rounded rock forms that are in 

 all countries the most striking result of glacial erosion. Such 

 rounded rock forms are present in abundance in some of the 

 fiords, but nowhere more frequently than in Thompson's Sound, 

 near Dea's Cove. Plate XXII gives an illustration of this, 

 where the wall of the fiord rises to a height of 4,000 ft., while 

 the water is 1,700 ft. deep. 



We are extremely fortunate in New Zealand in having a 

 well developed fiord region in which all the features charac- 

 teristic of such areas are to be found tj-^ically developed, and 

 at the same time a glacial region where the facts and principles 

 of the erosion that ice performs can be studied in detail. Even 

 at the present day the Fox Glacier has its terminal face only 

 600 ft. above sea-level. 



It cannot be doubted that every one who compares the 

 features of the two regions will come to the conclusion that 

 glacial erosion is responsible for all the main characteristics 

 of the fiords of the south-west of New Zealand. 



KOCKS. 



It has long been known that the Sounds region consists of 

 crystalline rocks, but very few descriptions of the actual rocks 

 have hitherto been given. Captain Hutton, in his " Geology 

 of Otago and Southland," includes all the Sounds rocks in his 

 Manapouri system of probable Archaean age. He mentions 

 granite, gneiss, granulite, syenite, and various other types, but 

 gives no descriptions of them. In another paper* he still in- 

 cludes these rocks in his Manapouri system, and states that 

 their age is Archaean. His third paper on the general structure 

 of New Zealandf makes no specific reference to these rocks, 

 though he apparently regards them as intrusive masses of Maitai 

 (Carboniferous) age. 



* Quart. Journ. Geo. Soc, 1885, p. 191. 

 t Trans. N.Z. Inst., 1899, ]>. 159. 



