76 president's address — section c. 



folds was first sharply drawn by Morgan (1908), who has since 

 supported it by further observations (1915). Henderson (1917) 

 has carried the study a stage' further, and remarks as follows . 

 " Apparently the PalaecEcdc recks of the West Coast have been 

 subjected to twoi series of foldings, the -cue producing north- 

 north-east strikes over a well-marked belt cf country from Reefton 

 to Separation Point if the other, less definite, affecting the rocks 

 westward of this zone, and producing noxth-westerly strikes. 

 Neither of these directions correspcnds with the- trend of the 

 plications of the Alpine chain, which are of late Mesozoic date, 

 and presumably quite distinct froui and younger than the folding 

 of the rocks west of the great series of overthrusts." This over- 

 thrusting is also ascribed to the Mesozoic mcvement. Neverthe- 

 less, as will be pointed out, a considerable crust-movement 

 occurred in Tertiary times also, in which a north-easterly strike 

 predominated. 



In the north-east of the South Island also, i.e., the Kaikoura 

 Ranges, though McKay (1892) declared the general direction of 

 the strike was to the north-east, Thcmscn (1918) considers this 

 opinion may have been based in large part en the appearance of 

 jointing rather than bedding planes, and shows that in a dozen 

 places at least the average direction of strike was to the north 

 north-w^est, and independent of the north-easterly strike of the 

 range as determined by late Tertiarj' faulting. This conclusion 

 was forethadowed by Cotton (1913), who has, moreover, shown 

 that the obliquity of the post-Tertiary fault-lines to the "grain'' 

 of the country is a rather general feature throughout New Zea- 

 land. It may be suggested that tangential thrusts, transmitted 

 obliquely to' the structural axes or "grain" of the basement rocks, 

 might well be expected to produce irregularities in the direction 

 of folding of the overlying strata. If this be the case in the 

 northern portion of the South Island, we may perhaps recognise 

 Otago and Southland as a region in which the direction of the 

 Mesozoic folding has been more nearly parallel with that of the 

 older north-we.^terly axis. According to Marshall (1912) the evi- 

 dence, tho'Ugh yet incomplete, appears to indicate that the south- 

 westerly trend lines of the Southern Alps diverge in the north- 

 west of Otagoi, and swing round intoi a south-east line of strike 

 Park shows that Queenstown forms the median area cf this virga- 

 tion, and the strike is here appropriately nearly meridional, but 

 further east changes to south -south-east near Cromwell, and it is 

 south-east at Lawrence, Marshall (1918) nearer the east coast. 

 Suess (1904) considered that two independent unilateral chains 

 meet in syntaxis at Queenstown; and Marshall (1912), while re- 

 cognising much more detailed work is required to prove this, be- 

 lieves the view a very probable one. 



t Spei<;ht (191(i) also calls attention to this feature in North-west Canterbury. 



