428 Transactions. — Geology. 



The evidence is, I think, conclusive that the Onekakara clay 

 belongs to the Pareora System. And this being so, it follows, 

 almost certainly, that the clay overlying the limestone a mile 

 south of Kakanui, which has been followed by Mr. Mantell 

 through AUday Bay to the Otepopo Eiver, also belongs to the 

 Pareora System ; and if it is the equivalent of the Hutchinson's 

 Quarry beds, as I suppose, they too must be put into the 

 Pareora. The only evidence wanting is the comparison of the 

 fossils from Hutchinson's Quarry with those from the clay near 

 Kakanui, and this I am not able to do as my lists are not suffi- 

 ciently complete. 



Volcanic Rocks. — The north side of Moeraki Peninsula is 

 formed by dolerites (S.G. = 2-88), which are seen on the shore 

 to overlie the Onekakara clay, here dipping 0° to 60° S.S.E. 

 In one place I noticed, in 1873, that the blue clay had been 

 altered by contact of a lava flow, and turned white for a distance 

 of 2 to 4 feet. These volcanic rocks are therefore much younger 

 than those described from the Oamaru District. Mount Charles, 

 between Herbert and the Otepopo Eiver, is also formed of 

 dolerites, which appear to overlie the greensauds and blue clay; 

 at the same time the greensands are formed almost entirely of 

 volcanic detritus derived from still older rocks. These dolerites 

 closely resemble those from Moeraki, but are sometimes coarser 

 in grain, and a less specific gravity (2-73), owing probably to 

 their being more altered. They are compact, and dark greenish- 

 grey in colour, or paler, owing to scattered greyisb-white flecks 

 which sometimes become very abundant. Under the micro- 

 scope they are seen to be holocrystalline, without any older 

 generation. The felspars are in lath-shaped crystals, usually 

 polysyuthetic. Sections, more or less parallel to the brachy- 

 diagonal, gave extinction angles up to 15° with the twinning 

 plane ; while long narrow sections, more or less at right angles 

 to the brachypinacoid, gave extinction angles up to 45°. From 

 tliis I judge the felspar to be labradorite. Augite of a pale 

 olive-brown, sometimes with black margins, occurs in imperfect 

 crystals ; and in a slide from Mount Charles I found a well- 

 defined crystal of rhombic pyroxene, giving straight extinctions. 

 This pyroxene is slightly dichroic, the vibrations parallel to the 

 macrodiagonal being pinkish-gieen, and those parallel to the 

 brachydiagonal olive-green. This pyroxene is not striated, and, 

 therefore, I suppose it to be enstatite. Ilmenite is abundant, 

 generally in thin plates from Moeraki, but more irregular from 

 Mount Charles ; it is much altered into leucoxene, which makes 

 the white flecks. No olivine was seen in any of these rocks. 



Lookout Bluff (the " White Bluft"" of Mr. Mantell's paper 

 already referred to) is an old and much-denuded volcano, com- 

 posed chiefly of agglomerate and ash beds. To the north, 

 scoriaceous sandstones, dipping to W. at various angles up to 



