478 Transactions. — Geology. 



coarse lumps. But, if it came from Coromandel, a great out- 

 burst might result in just such a bed at so considerable a 

 distance. In the third place, it grows coarser, on the whole, 

 in an easterly direction. At the Manukau the bed at the 

 White Bluff, though evidently the same, is yet rather finer 

 than at St. John's, to the east. I cannot say that I have 

 observed any increase of coarseness between Ponsonby and 

 Parnell, but between Parnell and St. John's College there is a 

 distinct increase. At Tamaki Head the bed is coarser than at 

 St. John's, while the outcrop in the reef is, on the whole, inter- 

 mediate between the two. It is very noteworthy that Mr. Park 

 was so struck by the increase of coarseness at Howick that 

 he described the bed there as " much coarser " than at Par- 

 nell. Had he seen the outcrops at St. John's, St. Helier's, 

 and Tamaki Head he would hardly have noticed the increase, 

 so gradual is it ; but it becomes noticeable when we com- 

 pare places far apart. Ponsonby is eight or nine miles from 

 Howick. At a spot between Little Muddy Creek and Avon- 

 dale I found what appeared to me an outcrop of the Parnell 

 grit. The bed weathered in concretions, and was, as usual 

 near vegetation, leached of its colour, and crumbly. It was 

 much finer than near Auckland, and only 10 ft. thick, and the 

 sandstones with which it was interbedded seemed to be lying 

 on Waitakerei lavas, but this I could not decide. It is so like 

 the usual outcrops of the Parnell grit that I see no stroug 

 reason for doubting its identity. If this be accepted, the 

 Parnell grit evidently did not come from the Waitakerei vents ; 

 and I think the evidence from coarseness is entirely in favour 

 of its having come from the east, not the west. Lastly, we 

 have the opinion of so excellent a geologist as Sir James 

 Hector, already quoted : " The Parnell grit, as far as I have 

 seen, contains no fragments of the volcanic rocks of the dis- 

 trict, but is green sand, with well-rolled pebbles of chert v 

 slate, quartzite, and other Palaeozoic rocks, and occasional 

 fragments of old trachyte and basic rocks of Cape Colville." 

 I might add that the volcanic inclusions are invariably in the 

 form of lapilli, full of steam-vesicles, such as one would ex- 

 pect to have come from a considerable distance. 



The age of the Coromandel volcanic gold-bearing series is 

 a matter of dispute; but Mr. Park, who has studied them, is 

 evidently convinced that they are about the same age as the 

 Parnell grit. He had in 1889 placed the grit in the Upper 

 Miocene, but for some reason he changed his mind, and wrote 

 in 1897: "Judging from the fossiliferous Parnell bed in the 

 Upper Eocene Waitemata marine series, on the shores of the 

 Waitemata, with its contained fragments of andesite and coarse 

 ash, the author is of opinion that the eruptions which origi- 

 nated these gold-bearing rocks began in the Upper Eocene 



