358 ' Transactions. 



The Weka Pass stone becomes glauconitic at its top, and passes quite 

 gradually into glauconitic mudstones. The succeeding sandstones are in 

 beds of 4 ft. to 10 ft., separated by mudstones 6 in. to 2 ft. thick. Some 

 of the sandstones contain small rounded pebbles of foraminiferal calcareous 

 sandstone, suggesting derivation by erosion from the Weka Pass stone. 

 In the higher beds the sandstones are in thinner layers and ,the mud- 

 stones thicker. Fossils are scarce throughout, and so tender as to be very 

 difficult of collection. E'pitonium zelebori was obtained low down in the 

 sandstones. Two shelly beds were noted on the right bank of the river, 

 below the grit, both containing Pecten huttoni, the higher being similar to 

 the polyzoan beds above the grit. The latter rock contains small pebbles 

 of greywacke. It is succeeded by alternations of thin polyzoan limestones 

 and bluish sandstones, and the latter beds continue to the base of the third 

 Moimt Brown limestone (C), and contain poorly defined concretions with 

 shells and plant-remains (Plate XX). Just above the polyzoan beds I 

 obtained Paphia curta and a fine specimen of Pecten heethami var. B Hutt. 



Part of the above sequence is repeated in the lower part of Boby's Creek, 

 north-east of the fault, and in the banks of the Waipara River above and 

 below the junction of Boby's Creek. The cuesta of the lowest Mount Brown 

 limestone (A) on the Ram Paddock is composed of a whitish polyzoan 

 calcareous sandstone, consisting chiefly of larger cup-shaped and smaller 

 Polyzoa,- and yielding fairly numerous but poor specimens of Pachjmagas 

 clarJcei n. sp., with rare pectens and echinoids. The limestone thins out 

 rapidly along its strike in both directions, and obviously formed a polyzoan 

 reef or shoal in the Oamaruian sea. To the west-south-west it crosses 

 the Natural Bridge Creek, greatly diminished in thickness, just above the 

 natural bridge, but does not continue to the east-north-east as far as the 

 banks of the Waipara River. It apparently thins out also in the direction 

 of its dip (south-south-east), but is presumably represented by the polyzoan 

 beds near the bottom of Boby's Creek and those above described in the 

 Waipara River. 



In the Natural Bridge Creek, and in Boby's Creek below it, there is some 

 gentle folding, so that a continuous section is difficult to trace. The 

 polyzoan beds appear to be the lowest horizon exposed, and are succeeded 

 by bluish muddy sandstones yielding Anomia trigonopsis, Pecten heethami, 

 Pecten huttoni, and Nucula sagittata Sut., the latter species being first 

 described from this locality. These are succeeded by current-bedded sands, 

 on which a cream-coloured sandstone rests unconformably. 



At the time of my first visit, in 1912, a recent slip had exposed a very 

 clear unconformity on the side of the bluff facing the Waip^,ra River at the 

 upper corner of the junction between Boby's Creek and the river (fig. 6). 

 The rocks below and above the surface of the contact were of similar nature — 

 viz., bluish muddy sandstone — but those below were not so clearly bedded. 

 The upper beds contained pebbles and boulders of the same nature, and 

 also of grey mudstones and of greywacke, as well as broken shells. This 

 section had become obscure at the time of my visit in 1913. A short 

 distance up the Waipara River, on the same bank, I observed some shell- 

 beds, which must lie above the unconformity, containing casts of Cucullaea, 

 ribbed Pectens, a large Dentalium, and many gasteropods. 



The lower part of the " grey marls " is exposed on the back of the cuesta 

 of Weka Pass stone between the limestone gorge of the Waipara River 

 and the saddle north-west of the North Dean. Here 50 ft. of grey mud- 

 stone follows the Weka Pass stone with every appearance of complete 



