Thomson. — Geology of Middle Clarence and Ure Valleys. 303 



massif, where a single fault dominates the structure, than in the south- 

 western part of the valley, where there are two or three parallel faults. 

 In the north-eastern part the strip of Notocene rocks lies wholly to the 

 north-west of the river, and is much nearer to the summit of the Kaikoura 

 than to that of the Looker-on Eange. Originally the river may have run 

 in the actual fault-angle, and if so it has doubtless been forced to the other 

 side of the valley by the heavy accumulations of talus that must have 

 accompanied the production of the fault-scarp. It is quite possible, how- 

 ever, that the actual angle was not the jjottom of the original tectonic 

 depression, and that the present course of the river is approximately the 

 axis of the original synclinorium. 



The fault-scarp of the Kaikoura Range along the line of the great 

 Clarence fault is not well preserved north-east of the Dee Stream, where 

 the crowded insequent tributaries of the Limburne, the Mead, and the Swale 

 have dissected the original front scarp. From the Dee south-west for some 

 miles there are steep spurs, passing into veritable facets of some thousands 

 of feet in height, above which appears a ])rominent bench. It seems pro- 

 bable that this part of the range has undergone a later renewed faulting, 

 for below it the relief forms cut in the Notocene rocks have been, according 

 to McKay's descriptions, completely covered with heavy deposits of gravel. 

 Cotton, who with the writer viewed this part of the valley from a distance, 

 describes it as a stretch of piedmont plain, now dissected, formed by the 

 coalescence of fans of coarse waste. 



McKay described and mapped the great Clarence fault as bending 

 obtusely at the Bluff River, and running obli(|uely to its former course 

 as far as Quail Flat, where it resumed its original direction. It is true that 

 a little to the south-east of the Bluff River the strip of Notocene rocks 

 pinches out, but it appears highly probable that the fault continues on in 

 its original direction for a considerable distance, bounded on each side by 

 pre-Notocene rocks. On the valley side these have not been worn to so low 

 a relief as the Notocene rocks farther north, owing partly to their strength 

 and probably partly to the fact that they form a smaller tilted block facing 

 a parallel fault along the line of the river from Red Hill to past the Herring 

 River, close to which they rise to heights of over 3,500 ft. The line of the 

 great Clarence fault to the south-east of the Bluff River appears, in a distant 

 view, to be marked by a series of well-preserved facets for a number of miles. 

 Doubtless, as between the Dee and the Muzzle, this part of the fault-scarp 

 o\\'es its origin to a later renewed faulting. It may be suggested that the 

 depression in which Lake McRae lies is on the continuation of the great 

 Clarence fault, and that it continues on into the valley of the Dillon River, 

 which is thus, like the Clarence, a tectonic depression. 



The greater part of the drainage of the mountain-ranges is, as already' 

 mentioned, accomplished by consequent streams which join the ClareiK-e 

 nearly at right angles, together Avith their insequent tributaries. These 

 streams run approximately south-east and north-west. In the mountains 

 to the west of the Upper Clarence there is a very marked deveIo2:)ment of 

 streams with north-north-east and south-south-west courses, suggesting a 

 well-developed subsequent drainage. The Elliott River joins the Clarence 

 River with a south-south-west course, immediately opposite the Gore River, 

 which has the same direction, flowing north-north-east. Both these rivers 

 rise in passes through the enclosing ranges, and the line of the two is 

 continued to the south-west by the Conway River, and to the north-east 

 by the Tone River and Castle Creek, tributaries of the Awatere River. This 



