496 Transactions. — Geology. 



Physical Chakacteristics. 

 Oamaru Stone. 



The typical Oamaru building-stone now being quarried at 

 Deborah, Totara, and Teschemaker's, on the main south rail- 

 way-line to Dunedin, is a soft pale- grey calcareous rock 

 principally composed of comminuted corals and foraminifera. 

 The quarries all lie east of the railway, along the eastern 

 boundary of the outcrop of the stone — that is, on the side 

 furthest from the old Tertiary shore-line. Passing south- 

 wards towards the Kakanui, and westward in the direction of 

 Weston, Enfield, Ngapara, Waitaki Valley, and other places 

 lying along or near the old Miocene shore-line, the Oamaru 

 Stone gradually merges into a yellowish-brown calcareous 

 sandstone containing the scattered remains of large echi- 

 noderms, a few brachiopods, Pseudamussium huttoni, and 

 Girsotrema broioni. Close to the old shore these forms are 

 mingled with examples of the littoral shells which abound 

 in the overlying Mount Brown beds. 



Mount Brown Beds. 



These beds generally consist of glauconitic sands, often 

 passing into a soft sandstone, or yellowish-brown coralline 

 sands and sandstones, which in places pass into rubbly or 

 impure limestones. In only a few places is there such an 

 excess of carbonate of lime as to warrant the quarrying of the 

 stone for burning into lime. 



These beds are easily distinguished from the Waitaki Stone 

 by the presence of a rich and varied fauna. In addition to 

 numerous corals, bryzoans, and broken echinoderm spines, 

 they contain a great assemblage of pectens and brachiopods, 

 many of which appear to be characteristic of this horizon. 



At Kakanui the Waitaki Stone is separated from the 

 Mount Brown beds by a considerable thickness of tuffs and 

 basalt. Passing westward the volcanic matter gradually 

 diminishes in tliickness, so that at Teschemaker's they are 

 separated by only a few feet. Westward of Weston they are 

 directly in contact with each other, the Mount Brown horizon 

 here consisting of glauconitic sands mixed with tufaceous 

 matter. 



It is a noticeable feature, perhaps seen to better ad- 

 vantage in the cliff-escarpments in the Waitaki Valley and 

 Waihao district than elsewhere, that the Mount Brown beds 

 gradually merge into the Waitaki Stone as they approach the 

 old shore-line, forming a single continuous calcareous horizon. 

 Each horizon, however, still preserves its distinctive features, 

 the Waitaki Stone being represented by the band of yellowish- 

 brown calcareous sandstone with Meoma crawfordi, &c, and 



