Mulgan. — The Waitemata Series. 429 



outcrop, as shown in accompanying sketch. Below is a coarse 

 conglomerate, merging into breccia, containing subangular 

 fragments up to 3 ft. in diameter, none of the blocks being 

 much waterworn. Above, the conglomerate gradually be- 

 comes finer, passing into coarse and then into fine grit, the 

 whole being capped by sandstones and shales. Throughout 

 the grit angular volcanic fragments up to 1 ft. in diameter are 

 scattered, and the whole, as elsewhere, is fossiliferous. 



The rock of which these blocks are composed is hard and 

 compact, with very large augite crystals and crystals of 

 feldspar showing plainly. Under the microscope the rock 

 appeared to be identical with that found at Coal-mine Bay, 

 except, perhaps, that the ground-mass was almost holocrys- 

 talline and the olivine more difficult to identify. 



From the presence of such large masses of volcanic rock 

 it would appear that the vent from which they were dis- 

 charged was somewhere in the immediate neighbourhood, 

 though I could find nothing to show in what direction it was 

 likely to be discovered. Possibly its site may be further 

 north or east beneath the waters of the Hauraki Gulf. 



On the southern shores of Whangaparaoa similar bands of 

 grit occur at intervals, but the outcrops are not so well 

 marked as those on the northern side, and the material of 

 which they consist is finer than that met with on the 

 opposite shore. There is little doubt that these outcrops are 

 merely the southern extension of those found on the northern 

 side of the peninsula. 



Section VII. — Grit-beds of the Manukau Harbour. 



Along the northern shores of the Manukau Harbour there 

 occur numerous outcrops of volcanic grit, both fine and coarse 

 deposits being abundant. In several places connection can be 

 traced between the outcrops, but more frequently this is not 

 possible. There is, however, with one exception, to be men- 

 tioned presently, absolutely no evidence to show that the 

 bands are distinct. 



The same formation prevails here as that found along the 

 shores of the Auckland Harbour, and in every case the grit 

 lies conformably between the sandstones and shales of the 

 Waitemata series. In many places the strata show evidence 

 of having been subjected to much disturbance, and faulting is 

 common all along the coast-line. 



The first outcrop of grit appears on the beach about a 

 quarter of a mile from the Village of Onehunga. It consists 

 of angular fragments ranging from very fine particles to those 

 the size of a pea, but in this place the outcrop is so weathered 

 that it is difficult to determine its composition. It here dis- 

 appears underneath the shore-line. 



