294 



i ransactions. 



Tap.le r. — General Classification of the Rocks. 



The Notocene rocks in the north-east half of the valley form an elongated 

 strip a few miles in width on the north-western side of the Clarence River. 

 At the Bluff River there are two separated exposures, the south-eastern 

 of which crosses the river and continues for some distance to the south- 

 west, and farther in this direction other isolated exposures occur. The 

 rocks rest with marked unconformity on the pre-Notocene rocks which 

 underlie them on the valley-floor, and of which, with their intrusives, the 

 liigher mountains are exclusively composed. The Notocene rocks dip in 

 almost all exposures steeply to the north-west, and on their north-west 

 side end abruptly against fault-lines, with the exception of the south- 

 eastern outlier at the Bluff River. The most persistent of the faults, known 

 as the great Clarence fault, runs along the base of the Kaikoura Mountains 

 a few miles to the north-east of the river, and is described by McKay as a 

 reversed fault. A monoclinal ridge of limestone, cut through by numerous 

 gorges, has been developed by erosion in the tilted Notocene beds a short 

 distance riverwards from the fault, and, rising to heights of about 3,000 ft., 

 form? a prominent series of foothills to the Kaikoura Mountains. The hills 

 clo3ing the north-eastern end of the valley, rising to 4,081 ft. in Benmore, 

 are a continuation of this monoclinal ridge, the line of strike bending 

 gradually from north-east to south-east. 



The probable geological history of the area, as interpreted from the 

 stratigraphy, structure, and physiography, is resumed in Table II. 



