Speight and Wild. — Weka Pass Stone and Amuri Limestone. 75 



(3.) Glauconitic calcareous sandstone : This is a distinct layer, about 6 in. 

 thick, of strongly glauconitic fine-grained calcareous sandstone, which passes 

 up into Weka Pass stone. 



(4.) Weka Pass stone: This is a distinctly glauconitic, arenaceous lime- 

 stone. The green and black nodules which mark the contact appear to 

 diminish in number on going south-west along the escarpment, but they 

 are occasionally present and so mark a continuous horizon ; but on approach- 

 ing the Waipara River the difference between typical Amuri limestone and 

 Weka Pass stone disappears, and the contact becomes indefinite — in fact, 

 the two beds merge into one limestone without any break. 



Main Branch of Weka Creek. 



There is an excellent exposure of the contact in the branch of the Weka 

 Creek north-west of the main road, just where it is crossed by the subsidiary 

 road running from Weka Pass behind the Mount Brown escarpment in the 

 direction of the Waipara River. The stream has in this locality cut a deep 

 narrow gorge right across the strike, and the contacts of the Weka Pass 

 stone with the underlying Amuri limestone as well as with the overlying 

 grey marl are excellently shown, both being quite conformable. 



In the case of the former contact we have the following sequence : — 

 (1.) Amuri limestone, breaking into quadrangular blocks, with interstitial 

 calcareous greensand in layers parallel to the bedding in its upper 

 portions, very occasional burrows extending to 6 ft. below the 

 actual junction. On approaching the junction the amount of 

 greensand becomes greater, both in layers and in burrows, till 

 near the contact the two form nearly equal proportions in the 

 rock. Thereafter the Amuri limestone diminishes in importance, 

 and inclusions of limestone in the greensand become rare. Dark- 

 green and black nodules (phosphatic) as well as ironstone con- 

 cretions also occur. The thickness of the layer where the two 

 occur is about 12 in. 

 (2.) Greensand layer, without inclusions of Amuri limestone, about 1 ft. 



in thickness, but passing up into 

 (3.) Weka Pass stone in its typical development. 



The contact between the two limestones is clearly seen on the escarp- 

 ment to the north, and is visible at times on the south as far as a limestone 

 knob a mile south of the creek, when for some distance towards the Waipara 

 the junction is obscured. As far as it is visible it displays the same charac- 

 teristic features. 



Upper Waipara. 



Excellent sections showing the relationship of the two facies of the 

 limestone are to be seen above the limestone gorge of the Waipara River 

 along the bold escarpment facing north-west. At the gorge itself there is 

 the following sequence : — 



(1.) The marly facies of the Amuri limestone forms the lowest portion 



in this locality, and passes up into 

 (2.) Typical jointed Amuri limestone with interstratified bands of argil- 

 laceous and glauconitic limestone. The upper layer of Amuri 

 limestone is a compact white rock containing glauconite, the 

 upper 6 ft. or 8 ft. with a concretionary fracture and passing up 

 into 

 (3.) Weka Pass stone of more than usual glauconitic character. 



