History of New Zealand. 249 
methods also occur. The long straight fault-lines shown on the map 
by McKay’ and the later maps by Park,? connecting up known 
portions of faults, must of necessity be highly hypothetical, and they 
probably fall far short of representing the facts; but it is true, never- 
theless, that to McKay belongs the credit of being the first to recognize 
the importance of faults in determining the Biya! features and 
geological boundaries. 
McKay’s views are strongly opposed to those of Hutton, who 
conceived only of regional (epeirogenic) movements of uplift and 
subsidence in later geological times.* Hutton recognized no young 
faults and no orogenic movements later than those at the close of the 
Jurassic except ‘‘a certain amount of folding” restricted to certain 
localities, which, he believed, took place ‘“‘at the commencement of 
the Tertiary ”.4 
‘* Not only,” he wrote, ‘‘ was the last touch given at this time 
commencement of the Tertiary] to the geological structure of the 
tSouthors Alps, but the chief valleys were also marked out at this 
period. 
‘For example, we find our oldest tertiary rocks occupying the 
valley of the Waitaki . . . and the Maruwhenua ... Inthe valley 
of the Shag they extend up nearly to its source... .’° 
To the explanation of the geological history of New Zealand thus 
expressed in 1875 Hutton afterwards closely adhered, as will be 
gathered from the following statements as to supposed changes in 
river courses, which are based on the assumption that the present 
relief has survived from very ancient times. This represents 
Hutton’s opinion in 1899: ‘‘ The Shag River at one time drained the 
‘Maniototo Plains until the gorge of the Upper Taieri was cut.. In 
early Cretaceous times the Hurunui and Waiau-ua united and entered 
the sea at Kaikoura. At. a later time they turned down the Weka 
Pass, and it was not until the Pliocene period that each cut its own 
valley to the sea. The Upper Manawatu flowed into the Wairarapa, 
and in the older Pliocene a river ran from the Manawatu gorge to 
Napier. The courses of all these rivers were changed by the 
deposition of marine rocks in the valleys, which blocked them; and 
this, on the subsequent rise of the land, caused the rivers to overflow 
to one or the other side, according to the position of the lowest 
opening.” ® 
The depressions, such as the Shag Valley and that extending from 
the Waiau to Kaikoura, regarded by Hutton as eroded valleys and 
assigned by him in the foregoing passage to ancient courses of various 
rivers, are more satisfactorily explained as tectonic features which 
came into existence in the Kaikoura period. 
1 N.Z. Rep. Geol. Expl., 1892, p. 1. 
2 J. Park, Geology of New Zealand, Christchurch, 1910, pp. 263, 265. 
* Geology of Otago, Dunedin, 1875, pp. 77-85 and pl. ii. 
* Loe. cit., p. 76. 
> Loc. cit., p. 77; cf. also ‘‘ Sketch of the Geology of New Zealand’’, 
Quart. Journ. Geol. Soc., vol. xli, p. 196, 1885. 
6 ‘«The Geological History of New Zealand’’: Trans. N.Z. Inst., vol. xxxii, 
p. 180, 1900. 
(Lo be concluded im our next Number.) 
