Grange. — Geology of Green Island Coalfield. 167 



Lima paucisidcata Hutt.. Pecten beethami var. B Hutt., P. huttoni (Park), 

 Turritella cavershamensis Harris, Pericosmus compressus Tate. 



Mr. J. Marwick looked over Hutton's specimens and obtained as well : 

 Chione chiloensis truncata Sut., Chione sp. ind., Malletia australis (Q. &■ G.), 

 and Venericardia pseutes Sut. 



Mr. Morgan collected Pachymagas parki (Hutt.) from the base of the 

 Caversham sandstone near Green Island Cemetery. 



All the mollusca occur in the Awamoan, and Pachymagas parli ranges 

 from the Ototaran to the Awamoan at Oamaru. 



There can be little doubt that the Waikouaiti and the Caversham sand- 

 stone are the same horizon. Marshall (1906, pi. xxxvi) maps the sandstone 

 of the latter locality continuously to the north of Blueskin Harbour, where 

 volcanic rocks make a separation from the sandstone of the former locality. 

 J. A. Thomson (1918, pp. 196-97) collected from the Waikouaiti sandstone 

 Pachymagas abnormis Thomson, which he states does not occur below the 

 Hutchinsonian at Oamaru. The Caversham sandstone with the greensand 

 appears to represent the Awamoan, Hutchinsonian, and Ototaran stages. 



The Balcombian beds are regarded by Chapman as Oligocene (1914, 

 p. 46), an age that J. A. Thomson (1920, p. 323) thinks corresponds with 

 the Waiarekan. The marl, then, may be placed in the AVaiarekan stage, 

 leaving the Paparoan and Kaitangatan for the underlying beds. 



VOLCANIC ROCKS. 



The following igneous rocks are described below : Basalt No. 1, basalt 

 No. 2, basalt No. 3, dolerite, trachydolerite, basalt dyke. 



Basalt No. 1. 



This rock occurs on the slopes of Abbott's and Kaikorai Hills. It is 

 the lowest volcanic outpouring in the Abbotsford Valley, and rests on an 

 eroded surface of the marine sedinientaries. There are two good outcrops — 

 one in a cliff below Kaikorai Trig., and the other at the back of Mr. 

 Meechan's house. At the former place the basalt, which is traversed bv 

 vertical and horizontal joints, is well weathered. At the latter locality 

 the upper portion is so greatly weathered that it would be difficult to 

 recognize it were it not for the more solid rock below. 



Macroscopically the rock is dark grey in colour. Where weathered the 

 augite crystals can be seen, but they do not protrude. This basalt may be 

 microscopically described thus : — 



Phenocrysts. — Labradorite (2-6 mm. X 0-66 mm.) is twinned on the albite 

 law. but at times there is a combination of the albite and pericline twinning. 

 Frequently it has magnetite inclusions in the centre. Augite is in large 

 isomorphic crystals (3-3 mm. x 1*5 mm.), and of a very light brown colour. 

 It exhibits slight pleochroism. Often this mineral has ortlfopinacoidal 

 twinning. Some crystals show zoning, the outer border being a little 

 more inclined to a violet colour, owing probably to the presence of 

 titanium. Olivine (1-5 mm. X 1-2 mm.) is allotriomorphie. Along fracture- 

 lines the mineral has changed to serpentine, and some crystals have been 

 entirely altered to this mineral. One crystal has inclusions of microlites 

 of feldspar. Magnetite occurs in grains. The ferro-magnesian minerals 

 are not plentiful, and there is a greater amount of augite than olivine. 

 Spherosiderite, with its irregular pleochroism, is in patches, and in one 

 section is seen as a narrow vein. 



