Thomson. — Geolof/y of Middle Clarence and U re Vcdleys. 



305 



Clarence River has been destroyed by the rejuvenation consequent on the 

 recent epeirogenic uplifts, which has worked back almost to their sources, 

 while a regrading has seldom extended more than a short distance from 

 their mouths. 



The Pre-Notocene Rocks. 



Owing to their monotonous character, and to the general absence of 

 distinctive lithological or fossiliferous strata which might give some indica- 

 tion of their structure and disposition, the study of the pie-Notocene 

 rocks is difficult. I have not attempted it, and must limit myself to such 

 casual observations as I have made. McKay has made a special study 

 of these rocks in certain areas, especially in the mountains between the 

 Wairau and Awatere Valleys, in the Muzzle, ajid between the Elliott 

 River and the Upper Clarence, and has attempted to establish a sequence 

 in the first and last localities ; the lowest beds he describes as grey sand- 

 stones and slaty shales with broken plant-remains, and these are followed 

 by a series of red and green rocks which are calcareous near Taylor's 

 Pass, between the Wairau and the Awatere ; similar rocks near the Elliott 

 River are again overlain by sandstone. 



The directions of strike and dip appear to be very variable, doubtless 

 owing to the folds of a smaller order, and to numerous faults, which tend 

 to obscure the major outlines of structure. On the whole, McKay describes 

 the rocks as striking in a north-easterly direction, with dips to the south- 

 east or north-west. Many of his observations, however, appear to have 

 been made at a distance, and cannot in these cases be accepted as alto- 

 gether reliable, since joint-control plays a large part in determining the 

 details of outcrop, and greywacke bluffs often trend transversely to the 

 strike. My own observations, resumed in Table III, would tend to show 

 that a strike west of north is prevalent in at least some parts of the area. 

 Cotton (1913, p. 241), arguing from the variability of the strikes and dips, 

 considers it probable that the older axes of folding make an angle with 

 those of the later Kaikoura folding — i.e., that the prevalent strikes are 

 oblique to the trend of the mountains. 



Table III. — Observed Strike and Dip of Pre-Notocene Rocks. 



