Speight. — Lower Waipara Gorge 229 



the south-west, and thus the gradual swing-round of the .strike of the 

 beds to the west of the river is easily explained. The amount of 

 pitch must be considerable, for the lowest beds actually exposed in 

 the gorge, at a height of about 100 ft. above sea-level, are the Grey 

 Marls, whereas the limestones which underlie the marls are exposed on 

 Mount Cass, about three miles to the north-east, at an elevation of 

 1,700 ft. It is possible, also, that the anticline not only pitches, but 

 dies out as well. It is certain, however, that it is distinctly unsym- 

 metrical, and the western limb dips down at a steeper angle than the 

 eastern limb. 



The direction of the strike observed in the river near the axis of 

 the anticline changes on following the escarpment towards Mount Cass. 

 It is at first parallel with the river, but, on being followed further, 

 strikes north-east with a dip to the south-east, and the beds forming it 

 lie in just the same relation to the limestones of Mount Cass and the 

 Limestone Range as the Mount Brown beds in the Weka Pass do to 

 the limestones occurring there. The similarity of the arrangement is 

 most marked. If the creeks between the escarpment and Mount Cass be 

 examined, the " Grey Marl " of the Survey is found in its proper position 

 and with characteristic development; but only the upper sandy beds 

 of these marls are visible in the gorge itself in the immediate vicinity 

 of the loop of the river and in the reach below it. The axis of the 

 anticline which runs out in the Waipara continues to the north-east, 

 the limestone of the Mount Cass ridge forming the limb dipping to the 

 south-east, while the north-east limb is represented by isolated blocks 

 to the north of the Limestone Range. At the core of the anticline, 

 immediately to the north of Mount Cass, lies a prominent hill, formed 

 of the underlying greywackes of Mesozoic age. This arrangement is 

 exactly what might have been expected from a consideration of the 

 structure and relationship of the beds in the Weka Pass and the Mid- % 

 Waipara 



As the anticline is traced to the north-east from the river it appears 

 to change to one of increasing asymmetry, so that some of the hard con- 

 cietionary bands on reaching to the inland side of Mount Cass become 

 nearly vertical. It is possible that on being followed further north-east 

 still it grades into a fault with a downthrow to the north-west, since 

 the limestones near the southern edge of the Omihi Valley, in the 

 neighbourhood of Limestone Creek, show a marked discordance in 

 level between those forming the crest of the ridge of Mount Cass, although 

 they dip in the same direction. More accurate examination of this 

 part of the country is necessary before a satisfactory conclusion can be 

 arrived at. 



The apparent bend in the axis of the anticline near the Waipara River 

 is perhaps due to this asymmetrical character, associated with the pitch 

 of the axis; it may, however, be due to a disturbance caused by folding 

 of the beds to the east of the mouth of the river in the neighbourhood of 

 the Teviotdale Station. 



On all the stretch of country forming the triangular area between 

 the Waipara River and the Teviotdale Creek the strike of the beds is 

 uniformly N. 55° W., with a southerly dip. They consist of sands, sandy 

 marls, loose gravels, and hard bands of conglomerate, composed of large 

 pebbles of greywacke and full of fossil-fragments. The beds are so hard, 

 however, that they rarely yield good specimens. One of the hard bands 

 forms the escarpment to the south-west of the Teviotdale Station ; another 

 forms a low indistinct parallel ridge to the north of this ; but the most 



