4 
394 Transactions. —Geology. 
On the Formation of Lake Wakatipu. By Capt. HUTTON. 
The formation of Lake Wakatipu has been ascribed by Dr. Hector (“Mining 
in New Zealand,” Trans. N.Z. Inst., II., p. 374) to unequal subsidence, while 
Mr. J. McKerrow (Trans. N.Z. Inst., III., p. 256*) ascribes it to the erosive 
action of a former glacier, in accordance with the theory put forward by my 
esteemed friend and instructor Professor Ramsay, which theory he has, in my 
opinion, reduced to a demonstration such as is rarely seen in geological 
inquiries. I need therefore scarcely say that I agree with Mr. McKerrow as 
to the glacier origin of Lake Wakatipu, but in order to establish my opinion 
I will examine what would be the results that an acceptance of the unequal 
subsidence theory would lead us to. 
Lake Wakatipu is a rock-bound basin, lying in a nearly north and south 
direction, with a sharp east and west deflection in the middle ; consequently, 
if it has been formed by unequal subsidence, this subsidence must have been 
most in a northerly direction, for if it had been in a westerly direction the end 
of the lake would have been at Queenstown. Of course, a southerly elevation 
would produce the same effect as a northerly depression. Now the deepest 
part of Lake Wakatipu is 1,400 feet, off Collins Bay, about 16 miles north of 
Kingston (McKerrow, l.c., p. 254), consequently, to change a horizontal surface 
to one having this slope, Kingston must have been elevated 1,400 feet more 
than Collins Bay, and this would give an elevation to the coast of Southland 
of 8,400 feet, and to Stewart Island an elevation of about 11,000 feet ; or, if 
the lake was caused by depression, Collins Bay must have been depressed 1,400 
feet more than Kingston, which would give a depression to Jackson Bay on 
the west coast, due north of Kingston, of 9,800 feet. These are the very least 
movements that can account for the phenomena, for if Kingston was not the 
axis of the movements, or if the movements had taken place in any other 
direction than that of the length of the lake, they would have to be immensely 
increased in order to bring about the same result. But most of the sounds, 
the origin of which Dr. Hector also ascribes to the same movements, are south 
of Lake Wakatipu, and are therefore situated in that part which would have 
undergone the least depression, so that they are just where they ought not to 
be if this unequal depression has occurred over the whole country. Lake 
Monowai also requires that the depression should have been towards the south 
instead of the north. If also movements on such an extensive scale had taken 
place since the pleistocene period, the river system of Otago would be certain 
* In this paper Mr. McKerrow points out, I believe for the first time, the very im im- 
portant fact that the constrained flexure of a molia body = eee ven passing | from ¢ one 
angle of inclination to another, would greatly i tl 
