1919.] 
Cotton.—Notocene Beds of Central Otago. 
71 
somewhat subangular character, and evidently derived from the mica 
schists ” (Hector, 1884). These beds were horizontal where passed through, 
though the quartz drifts stand at high angles at a point 240 yards distant, 
being vertical where in contact with the undermass (p. 45). 
The various accounts of the Otago goldfields indicate that a great 
thickness of the so-called quartz drift, which varies from quartz grit or 
coarse sand to fine or, more rarely, somewhat coarser quartz conglomerate, 
occurs very frequently near, and sometimes at, the base of the sequence. 
There is frequently, however, brown coal and shale at the base, and the 
quartz grit may be relatively thin and interstratified with beds of clay. 
Over considerable areas a bed of quartz grit a few feet in thickness is 
cemented into a very hard siliceous conglomerate — a veritable quartzite. 
The other beds are relatively very weak, and it is this cemented layer 
which survives in places as isolated boulders—the “ sarsen stones ” pre¬ 
viously referred to — when the weak beds have been entirely removed. 
There is often a considerable development of alternating beds of clay and 
fine sand, forming collectively a great thickness. 
A comparison of the various accounts does not show that the order 
of succession in these beds is constant; but, always overlying this series 
of clays, sands, and quartz conglomerates, which, it is generally agreed, 
are derived from the degradation of schist rocks similar to those forming 
the undermass in the Central Otago area, there is usually present a 
further succession of gravels and sands derived from sedimentary forma¬ 
tions similar to those now present farther north and known familiarly 
to New Zealand geologists as the “ greywackes.” It is possible that this 
change to greywacke gravel marks the beginning of the Kaikoura orogenic 
movements in the Southern Alps, though it is clear that other parts of the 
South Island were not deformed until somewhat later. The change suggests 
a tentative correlation of the Notocene greywacke gravels of Otago with 
the conglomerate forming the upper members of the marine succession 
in the North Canterbury district. 
The quartz grits or “ drifts ” have been often examined on account 
of their auriferous character. McKay (1897) distinguished an “ older ” 
(marine) series underlying the fossiliferous marine Oamaruian of the coastal 
district, and a “ newer ” (fresh-water) series which occupies the greater 
portion of the Central Otago chain of depressions. It may be that such 
a differentiation is possible, the latter being terrestrial beds contempo¬ 
raneous with marine stages developed elsewhere and overlapping the area 
covered by the former ; but the distinction between the two series seems 
arbitrary and impossible of application. 
To what Extent are the Beds of Fluviatile Origin ?—Basing his observations 
on the physical conditions obtaining in Otago at the present day, McKay 
came to the conclusion that material such as that forming the quartz grit 
could not be produced by stream-action, but only by wave-action on a 
beach. The sorting of the material of the “ older ” series was therefore 
ascribed to wave-action on the ocean-beach, and the “ fresh-water ” series 
was supposed to have been produced by wave-action in a large lake in 
the interior. Referring to this “ fresh-water ” series of quartz “ drifts,” 
he wrote:— 
[At a large number of widely separated localities, mentioned by name] 
“ the beds betray everywhere the same sequence, exhibit the same character, 
and indicate not a number of comparatively small lakes, but a vast inland 
