366 Transactions. 



Tridymite-Trachyte of Lyttelton," by P. Marshall (vol. 26, 1894) ; "An 

 Olivine-andesite of Banks Peninsula " (vol. 25, 1893), " On a Dolerite 

 Dyke from Dyer's Pass" (vol. 26, 1894), and "On a Soda Amphibole 

 Trachyte from Cass's Peak, Banks Peninsula " (vol. 40, 1908), by the 

 present author. There are also a few other papers on general geological 

 subjects connected with the area, such as a " Note on the Silt Deposit at 

 Lyttelton" (vol. 15, 1883), by Captain Hutton ; "Note on an Artesian- 

 well System at the Base of the Port Hills" (vol. 33, 1901), by S. Page 

 and E. B. R. Prideaux ; and, lastly, a paper " On a Remarkable Dyke 

 on the Hills near Heathcote " (vol. 13, 1881), by A. D. Dobson. 



With the exception of several slight references in the writings of others, 

 this is all that has been written on the district ; and as no general account 

 of this interesting locality has been issued since 1879, and no comprehensive 

 account of its petrology has yet been published, no excuse need be put 

 forward for this paper. 



B. GENERAL TOPOGRAPHY OF THE AREA. 

 (See fig. 1 and Plate XXIV.) 



Banks Peninsula was discovered by James Cook on the 14th February, 

 1770, while on his first voyage of discovery. He thought it was an island, 

 and named it after the celebrated naturalist who accompanied his first 

 expedition. No landing was made, the nearest approach being about three 

 to four leagues distance. He says with regard to it, " It is of a circular 

 figure, and about twenty-four leagues in compass. It is sufficiently high 

 to be seen from a distance of twelve to fifteen leagues, and the land has a 

 broken, irregular surface, with the appearance of barrenness rather than 

 fertility. Yet it was inhabited, for we saw smoke in one place and a few 

 straggling natives in another." Cook's mistake as regards its being an 

 island can be easily understood when one considers the difficulty of picking 

 up the low-lying land on the south and west from a ship over twenty 

 miles away off shore. 



The peninsula lies'in latitude 43° 32' S. and longitude 173° 30' E., 

 and forms a rough elliptical salient on the central portion of the South 

 Island of New Zealand. Its diameter in a N.W.-S.E. direction is about 

 twenty-five miles, and its breadth at right angles thereto about eighteen 

 miles. It is bounded on the north-east, east, and south by the sea ; but 

 on the other side, looking toward the Canterbury Plains, the place of the 

 sea is taken by the estuary of the Avon and Heathcote Rivers on the north- 

 west, by low-lying and swampy land on the west, the latter passing into 

 marsh and shallow lake on the south, where the flat expanse of Lake Elles- 

 mere lies behind a great shingle-spit whose proximal end is attached to the 

 south coast of the peninsula. Near this point another body of brackish 

 water, known as Lake Forsyth, is ponded back in the lower reaches of one 

 of the main valleys stretching south. About forty miles away to the west 

 is the long line of the Southern Alps, and sloping up to their foot lie the 

 Canterbury Plains, formed by the coalescing and overlapping fans of the 

 shingle-charged rivers issuing from the mountain tract. 



The most striking features of the peninsula are Lyttelton and Akaroa 

 Harbours, occupying old volcanic craters of the " caldera " type, surrounded 

 by crater-rings, which are broken at one place so as to allow of the entrance 

 of the sea into the depressed floors of the craters. The centres of the two 

 craters occupy, as it were, the two foci of the elliptical area constituting 

 the peninsula. The former lies to the north of the area, and stretches in 



