458 Transactions. — Geology. 



occupy the same horizon, and that the Parnell grit is the 

 older."* 



This led Mr. Park to defend his views.! To Mr. McKay 

 he replied that the Cheltenham breccia might quite possibly 

 underlie the Calliope Dock beds, because a basalt cone of 

 more recent date lay between the two and obscured their 

 stratigraphical relations. This was, so to speak, negative 

 evidence ; but he added that at Parnell, in the lower 2 ft. of 

 the grit, he was fortunate enough to find some fossils (a 

 Pecten, a Cerithium, a Teredo, and several small corals), and 

 he wrote : " The Cerithium, Pecten, and corals are the same 

 as those found in the breccia at Cheltenham, thus proving 

 conclusively that the Parnell grit is the southern extension 

 of that stratum, deposited at the same time and under the 

 same geological conditions." Mr. Park made good use of 

 his fossils. As he does not give even the generic names of 

 the corals they need not be considered. Surely it is possible 

 for two beds of nearly the same age to have Pecten polymor- 

 phoides and an unknown Cerithium associated together,, 

 especially as Pecten polymorphoides has a wide vertical 

 range and is a common Miocene fossil. 



As far as I know this is all the evidence in favour of the 

 beds being identical. Since, however, the beds are both 

 volcanic breccias and similar, and there is a stretch of water 

 two miles in width between the two, it is reasonable to sup- 

 pose them identical unless there is good reason for thinking 

 them distinct. The evidence for the latter view is as fol- 

 lows : — ■ 



(1.) The beds are not entirely similar in lithological 

 characters. In the case of the Cheltenham breccia the bed 

 consists almost entirely of volcanic fragments, some of them 

 (though this is rare) Sin. in diameter. In the Parnell grit 

 most of the fragments are greensand, slate, &c, while onlv 

 in the lower layers do we find volcanic fragments of any size, 

 and these are rounded, well-worn scoria, generally oxidized, 

 and never more than 1 in. in diameter. There" are other 

 minor differences, but the difference in texture is the point 

 which I wish to emphasize : in the one bed numerous lumps 

 the size of an orange, hard, black, and angular; in the other, 

 red, rounded, scoria fragments not larger than marbles. This 

 difference is brought prominently before one when trying to 

 obtain a suitable fragment at Parnell from which to make a 

 microscopic section. It must be remembered that the Parnell 

 outcrop is not more than two miles and a half from the 

 Cheltenham outcrop. It is in that distance that the texture 



* Geological Reports, 18S8-89. 

 t Trans. N.Z. Inst., 1889. 



