Pakk. — On the Waitemata Series. 391 



Art. XLVI. — On the Conformable Relations of the different 

 Members of the Waitemata Series. 



By James Park, F.G.S., Lecturer, Thames School of 



Mines. 



[Read before the Auckland Institute, litti October, 1889.] 



Plate XXX. 



The beds forming the cliffs on the shores of the Waitemata 

 generally occupy a more or less horizontal position, but at a 

 few places they have been subjected to great local disturb- 

 ances, often resulting in sharp contortions and faulting. 

 Strangely enough, these disturbances have in many instances 

 occurred at what may be termed critical points from a geo- 

 logical standpoint, and have thus caused obscurities which have 

 led to much discussion and controversy, not only as to the 

 age of the beds tlieniselves, but also as to the relations which 

 the different beds bear to each other. 



The covering of Pleistocene lavas and scoria on the isthmus, 

 and the numerous small bays or inlets which diversify the 

 shores of the harbour, have rendered it difficult, if not quite 

 impossible, to trace particular beds from place to place, while 

 the absence of well-marked fossiliferous horizons has always 

 been an obstacle to the safe correlation of distant beds of the 

 series. 



The Waitematas, with perhaps the exception of the Par- 

 nell grit or ash-bed, contain no beds possessing mineral 

 characters sufficient to constitute chronological landmarks in 

 the geological succession that would enable the field-work to 

 confidently affirm that certain beds in one locality were the 

 horizontal equivalents of other distant beds — as, for example, 

 that the Port Britomart beds were the same as the beds at 

 the head of Hobson's Bay, or the North Shore beds the same 

 as the beds north of Whangaparaoa Peninsula. The whole 

 series consists chiefly of frequent alternations of blue clays and 

 soft sandstones, sometimes succeeding each other rapidly as 

 thin-bedded strata, sometimes as heavy bands varying from 

 2ft. to 10ft. in thickness. 



The Fort Britomart beds, which may be taken as cha- 

 racteristic of the greater part of the series, consist of thin 

 layers of blue crumbling clays alternating with layers of soft 

 brownish-coloured sandstones. The clays vary from a few 

 inches to a foot in thickness, and the sandstones from a few 

 inches to 3ft. Fragments of carbonized wood, often laid in 

 continuous layers, are not uncommon in the sandstone bands ; 

 and it is a noticeable feature that where the coalv matter is 



