Speight. — Redcliff Gully, Rakaia River. 



339 



Captain Hutton states that there is no disturbance of the beds, a con- 

 clusion based, I believe, on an incomplete examination. The steep iaclination 

 of the series as seen in the slip facing Cascade Creek is continued towards 

 the west, and on following the outcrop of the limestone towards the south- 

 west it is found to swing round and become steeper still. There is a gap 

 then m the line of outcrop, but the limestones appear again on the east 

 side of the upper part of Packer's Creek, and here they are in all probability 

 almost vertical, if not slightly overturned. This observation is, however, 

 somewhat doubtful, as the planes of stratification could not be determined 

 with certainty. The beds appear to form a basin-shaped syncline, although 

 I could see no sign of the sandy beds which overlie the limestone in the posi- 

 tion that they should occupy on its western Mang, owing to the morainic 

 and other detrital accumulations on the surface. This appears to me to be 

 the most satisfactory explanation of the structure of the beds in this part 

 of the area. On the north side of this syncline there is a block of limestone 

 which also shows synclinal structure with the axis running nearly north. 

 On the western flank the beds have a slight dip to the south-east, and are 

 distinctly overlain by the shell-beds which usually cap the limestone. They 

 are thus in the position required by the presence of the syncline. The lime- 

 stone on the western wing of this syncline forms a high escarpment fronting 



f^'rcr Se^ ■ = 



Fig. 2. — Profile of Limestone Escarpments, Redcliff Gully. 

 As seen from Castle Rock Island, Rakaia River, looking south. 



the middle part of Packer's Creek. Its southern termination is 500 yards 

 distant from the block in the upper part of Packer's Creek, and is 300 ft. 

 above it. It seems, therefore, that a fault is present, the effect of which has 

 been to raise the middle block of limestone relatively to the southern block, 

 or to depress the southern block relatively to the middle block (see fig. 3). 

 This fault is in the nature of a flaw or hlatt cutting the main direction of 

 folding nearly at right angles. It is unfortunate that no exposure of rock 

 allows the structure of the syncline to the south to be definitely determined, 

 but this appears to be the only explanation, especially when taken in con- 

 junction with the structure of the most northerly block — viz., that over- 

 looking the Rakaia directly. This also appears to be separated from the 

 middle block by a flaw or hlatt, the effect of which is to cause an apparent 

 downthrow of the block to the north. This fault does not pass right through 

 the series to the east, but its effect is noticeable in the sagging downward 

 of the limestone scarp on the east from its greatest height in the slip facing 

 Cascade Creek as it is followed north to towards the Rakaia. On tracing 



