Mulgan. — The Waitemata Series. 



121 



low platform on the beach, it is difficult to be sure either of 

 the direction or the angle of the dip. 



Fig. 3. 



Auckland 



Ha rb our 



Y. 



A', 



arrow 



Neck 



Plan 

 1 





N 



A 



Cheltenham 

 Beach 



of Cheltenham Beach ash-beds: 

 Band of volcanic grit. 2. Sand- 

 stones and shales (shows here (2) as 

 dome). AB. Low sandy flat called 

 the " Narrow Neck." 3. Outcrop of 

 grit further north, only showing on 

 beach. 



The two outcrops showing along 

 the shore-line at CD and again at E 

 are evidently portions of the same 

 land as shown in above plan. This bed, dipping east at CD, 

 has presumably had its dip changed by the same force which 

 formed the dome, and appears again at E dipping west. The 

 strata at the end of the point are truncated by a fault as 

 shown. To the southern side of the point the dip rapidly 

 increases until at the fault the strata become vertical. 



In a paper read before the Auckland Institute in 1889 Mr. 

 Park gave a plan of the Cheltenham Beach ash-beds. In 

 this, however, no notice is taken of the change in the direction 

 of dip in the two exposures, nor is any mention made of the 

 dome. Both of these matters have an important bearing on 

 the question under discussion. Furthermore, the northern 

 outcrop is obtained by producing the line CD (fig. 3), 

 whereas in point of fact it occurs considerably to the west of 

 this position. 



The outcrop at F (fig. 3) may have reached its present 

 position owing to being horizontally displaced by a strike fault 

 running east and west. The low swamp occurring between 

 the higher cliffs on either side may well indicate some faulting 

 of the strata, in consequence of which the sea has been able 

 to effect an entrance and erode the narrow valley, now become 

 a dry sandy flat. Additional force is lent to this theory by 

 the fact that a line drawn across the narrow neck east and 

 west would pass through low mud-flats and the waters of 



