Marshall, Speight, Cotton-. — Yoxnger Hoch-s^eries of IWZ. 389 



syncline or the south limb of the anticline beyond alone remain. Not 

 only does this simple structure explain the somewhat irregular nature 

 of the outcrops, but also the sudden bend of the Weka Pass Creek 

 into the hard limestone, for this course we believe it followed in the upper 

 softer beds above before it corroded its bed as low as the surface of the 

 harder rock. In addition to this observation, there is further evidence in 

 the parallel nature of the outcrops of the Mount Brown and Weka Pass 

 stone between the Weka Pass and the Waipara Gorge. Standing on the 

 summit of Mount Donald and looking southward, this is a particularly 

 marked character. The two beds are hard, and dip approximately S.E. 

 at an angle of from 15° to 20°. Sharp escarpments have naturally been 

 formed, and are the dominating features of the country. They can be 

 seen and followed Avith the utmost distinctness over miles of country 

 without any bend in the strike of either being noticed. This statement 

 is in perfect accord with the observations of McKay quoted earlier. 



3. Relation of Grey Marl to Mount Broivn Beds. — Hector, McKay, and 

 Hutton agree on an unconformity here ; Haast and Park have failed to 

 observe one. Hector and McKay rely mainly on the junction of these beds 

 exposed in the Waipara Gorge. This junction is now well exposed, owing 

 to the formation of a road-cutting. We examined this with great care on 

 the 6th February, 1910, and unreservedly agreed that in this clear section 

 there is no unconformity whatever, but a gradual change from the one 

 formation to the other. Hutton relied mainly on a railway-cutting in the 

 Weka Pass a little south of the 44th mile-post. Here there is a clear break 

 in the stratification. However, the beds on the two sides are of the same 

 nature (Mount Brown beds), and the plane of union is most regular, and 

 inclined 45°. This we believe to be a small fault, but the throw cannot be 

 measured. Park and Hector do not mention this section. 



4. The Junction between the Mount Brown and Greta, Motunau, or 

 Awatere Beds of Different Classifications. — PaiJc alone has described an 

 unconformity here. The section on which he relies is near the 43rd mile- 

 stone. The coralline sandstone (of his Mount Brown or Miocene series) 

 that he describes as having an isolated outcrop at the south-east we found 

 was continued without break above the sands that he refers to the Motunau 

 or Pliocene series. At the north-west end there is no indication of uncom- 

 formity on the south-west side of the cutting to which he refers. The 

 section here, however, is so much obscured by vegetation of many years' 

 growth that details were not distinct. On the north-east side of the section 

 the details are perfectly distinct, and there is a complete conformity in the 

 series. In regard to this matter we are in agreement with all the other 

 geologists who have examined this country. 



Careful and detailed examination of all these described unconformities, 

 made with descriptions and diagrams of previous observers in our hands, has 

 convinced us that there is no unconformity in the Waipara and Weka Pass 

 sections. 



(b.) The Amuri Bluff. 



Here McKay has described a complete conformity, but Hutton states 

 that on the south side of the Bluff the Amuri limestone is unconformable 

 to the Grey Marls which here overlie it to the exclusion of the Weka Pass 

 stone. This unconformity is based on the change in dip of the two series. 

 Our observations showed that the Grey Marls dip more and more steeply 

 as thev are followed to the west, and that the Amuri limestone does not 



