Thojison. — Gfolor/!i of Middle Clarence a/ul l^re Valleys. 299 



Clarentian beds occur in the South Island only in the Clarence and Awatere 

 Valleys, and in the hill near Charwell Flats, south of the Looker-on Range, 

 where Dr. Cotton and I found " Modiola " kaikoiirensis in conglomerates 

 forming the base of the Notocene at that point. Possibly, however, 

 the basal beds of the Notocene in the Puhipuhi Mountains and the Cape 

 Campbell Range are also of the same age. The thickness of the known 

 Clarentian rocks varies rapidly from place to place, suggesting the proximity 

 of land during their deposition. The basal beds from the Herring River 

 to the Bluff River are terrestrial, and the marine rocks, of which the series 

 mainly consists, are throughout terrigenous, consisting of conglomerates, 

 sandstones, and mudstones, with glauconitic rocks but feebly developed. 

 The thickness of the series, 3,000-9,000 ft., exceeds that of the whole 

 Notocene series in localities such as Oamaru, where peneplanation of the 

 oldermass is known to have been complete before sea-advance, and, com- 

 bined with the lithological characters, afiords clear evidence that consider- 

 able erosion of not very distant land was going on throughout the whole of 

 the Clarentian. Although the nature of the surface of deposition as seen in 

 unconformable junctions suggests that the relief of the oldermass was not 

 great, the physiographical evidence for peneplanation is not strong, and 

 it is quite possible that during the Clarentian land may have existed on the 

 site of the Kaikoura and Looker-on Ranges, breaking the continuity of the 

 cover laid down on the oldermass. In estimating the minimum extent 

 of the Kaikoura deformations by adding the thickness of the Notocene 

 to the present heights of the mountains, it is therefore wise to omit the 

 thickness of the Clarentian. For the Kaikoura Range, however, it is neces- 

 sary to take into account the Clarentian volcanics, since the range is seamed 

 with dykes between the present outcrops of these rocks in the Clarence and 

 Awatere Valleys, and at least 1,000 ft. should be allowed on this account. 



The total results of the Kaikoura deformations consisted in the forma- 

 tion of two immense tilted blocks, the Kaikoura and Looker-on Ranges, 

 bounded by great fault-scarps on their south-east sides, with an inter- 

 mediate fault-angle, the Middle Clarence Valley. Hector (1886, pp. xiv, xv) 

 described the nature of the movements as an extremely local but bold 

 anticlinal fold, the crown of the arch of which collapsed with the formation 

 of a deep longitudinal groove, and considered that the thrusting force 

 which produced the reverse fault came from the west. Cotton (1913, p. 227) 

 considered the results of the movements as the production of two anti- 

 .clinoria, the axes of which correspond with the ranges, with an intermediate 

 synclinorium, one limb, however, being represented by a reversed fault 

 of enormous throw. It appears probable, both from the lack of summit 

 accordance in the north-eastern parts of both ranges and from the strong 

 folding which the Notocene beds have experienced near the Bluff and the 

 Ure Rivers, that the deformation was not simple tilting but was accompanied 

 by folding, and that the initial surface was, at least in places, warped into 

 anticlinoria Vvdth an intermediate synclinorium before faulting took place. 

 vSince a cover of at least the Clarentian volcanics and the middle Notocene 

 rocks — say, 4,000 ft. — must have once occupied the sites of the Kaikoura 

 Slountains, the total vertical movement must have been at least 13,000 ft. ; 

 but if a preliminary folding took place the total displacement along the 

 fault-lines may have been very much less. Cotton (1913) in his diagram 

 represents the great Clarence fault with a throw of 8,000 ft. or 10,000 ft., 

 but states that it is possible that it is considerably more, and that there is 

 no way of arriving at an accurate estimate of its amount (see fig. 3). 



