324 Transactions. 



Peninsula by way of the Front Range at Kekerangu and the Puhipuhi 

 Mountains, and there can be no doubt that the Amuri limestone of Amuri 

 Blufi correlates with some part, but it is almost certainly only the upper 

 part, of the liniestone of the Clarence Valley. It would therefore be more 

 appropriate to name the formation from its greatest development in the 

 Clarence Valley, but the name '' Amuri limestone " is too well established 

 to be displaced. 



McKay correlated the uppermost part of the limestone formation in 

 the Clarence Valley with the Weka Pass stone, describing the rocks as 

 calcareous sandstones. Although in the north-east part of the valley 

 there appears little justification for any such distinction, in the Herring 

 River beds of greensand with phosphatic nodules and volcanic tuffs separate 

 an upper, light-brown limestone from the lower, white Amuri limestone. 

 Everywhere in North Canterbury and at Amuri Bluff and Kaikoura 

 Peninsula a bed of phosphatic greensand or glauconitic limestone separates 

 the Weka Pass stone from the Amuri limestone (c/. Speight and Wild, 

 1918), and it seems probable that the phosphatic band in the Herring 

 River represents the same horizon and that the upper limestone must 

 correlate with the Weka Pass stone. 



The Amuri limestone in the Clarence Valley, excluding the flint-beds, 

 consists mainly of two types of limestone, the one a snow-white, very 

 fine-grained, hard, almost flinty rock, composed almost solely of carbonate 

 of lime and silica ; the other an equally fine-grained but somewhat softer, 

 argillaceous limestone, also light-coloured but not so white, and very often 

 with a greenish tinge. The former rock forms thick strata, and also 

 alternates in thin beds, up to 1 ft. thick, with the latter, which is less 

 commonly found in thick beds. The former may for convenience be 

 termed the chalky type, and the latter the marly type. 



The base of the limestone formation is in most exposures formed of 

 beds consisting wholly or partly of black flint, but in the upper part of the 

 flint-beds the flints are often light-coloured. Where the beds are partly 

 of flint, the latter form large lenticules and the outer part consists of 

 flinty limestone of the chalky type. In many places, however, the outer 

 part is grey and crystalline, the crystals consisting of dolomite set in a 

 matrix of flint. I have described the peculiar nature of these beds fully 

 in my former paper (1916). Flints also occur sporadically in the upper 

 parts of the limestone, but are not abundant and are not aggregated into 

 definite rows. 



Mead Gorge. — The greatest thickness of the Amuri limestone is that of 

 the Mead Gorge, Avhere I estimated it as follows :- 



2,750 



The dip of the various beds is constantly to the north-west, at angles 

 varying from 45° to 70°, the average angle being between 50° and 55°. 

 The junction with the underlying Clarentian beds is not exposed. The 



