360 Transactions. 



Weka Creek. — In the Weka Creek the contact of the Weka Pass stone 

 and " grey marls " is well exposed. Speight and Wild (1918) have noted 

 that the agreement in dip is absolute, and the contact does not show any 

 signs of unconformity, hut the Weka Pass stone exhibits on its upper 

 surface a narrow bored zone similar to that on the upper surface of the 

 Amuri limestone. " This is succeeded by 1 ft. of slightly glauconitic sandy 

 marl, then by 12 ft. of slightly glauconitic sandstone, passing up into 

 sandy marl and becoming more argillaceous higher up but still preserving 

 'something of its arenaceous nature." 



The thickness of the sandy mudstones is difficult to estimate, as the 

 creek here runs obliquely to the strike, but is about 70 ft. Near the top 

 Amusium zitteli is fairly common, and there are also casts of other bivalves 

 and gasteropods, at least two species of coral, fish -scales, and Foraminifera. 

 Such shells as exist are mostly too fragile to collect. The mudstone is 

 succeeded by a sandstone, and then there are alternations of sandstone 

 and mudstone up to the horizon of the second Mount Brown limestone (B). 



Weka Pass. — In the middle part of the Weka Pass Stream from the 

 road-bridge over the stream downwards, and in the railway-cuttings oppo- 

 site, there are several isolated exposures of the " grey marls," but no 

 continuous section. The lowest beds, at the bridge, are typical sandy 

 mudstones resting directly on the Weka Pass stone. The actual junction 

 cannot be observed, but only about 3 ft. of beds is not exposed, and each 

 rock appears to be approacheng the other in composition. From these 

 sandy mudstones,- which appear to be about 50 ft. thick, I collected casts 

 of Verconella, Crassateliies, Loripes, Nucula, and Nticulana. 



Lower down the stream there are two large cliffs of well-bedded soft 

 grey sandstone, and similar beds are exposed in the railway-cuttings above. 

 The thiclcness of these sand.stones does not probably exceed 200 ft. They 

 are again succeeded by a sandy mudstone of unknown thickness, exposed 

 at the first bend of the stream above the cliff of the lower Mount Brown 

 limestone described below: These are succeeded by loose sands, passing 

 into a grey mudd}^ sandstone, together about 50 ft. thick. 



In the upper part of the Weka Pass Stream only the lower part of the 

 " grey marls " is exposed, as a typical sandy mudstone near the viaduct. 

 From this rock I collected Limoj^sis aurita Brocchi (?) and Foraminifera, 

 and McKay's earlier collection included Ampidlina niiocaenica Suter. A 

 selection of the Foraminifera supplied by Mr. F. Chapman was as follows : 

 Clavulina communis d'Orb., Bulimina inflaf.a Seguenza, Ehrenbergina serrata 

 Reuss, Nodosaria vertebralis Pteuss, N. prismatica Reuss, N. consohrina d'Orb., 

 N. longiscata d'Orb., Lingidina costata d'Orb., Cristellaria vortex d'Orb., 

 C. gyroscalprum Stache, Glohigerina triloba Reuss, Truncatulina tliiara (Stache), 

 Anomalina ammonoides (Reuss), Pidvinulina karsteni Reuss, and Rotalia 

 soldanii d'Orb. These indicate, according to Mr. Chapman, that the horizon 

 is probably Eocene. 



Ther.e are two prominent calcareous horizons in the Mount Brown beds 

 on the south-east side of the Weka Pass, lying about 400 ft. and 800 ft. 

 respectively above the Weka Pass stone. The upper horizon (D) forms 

 an escarpment on the crest of the ridge, and the lower (B) presents a less 

 prominent escarpment as a salient half-way down the slope, but in the angle 

 between 'the W^eka Pass Stream and the Weka Creek it forms a separate 

 lower cuesta in front of the cuesta of the main band (D), and it assumes 

 the same physiographic prominence between the Weka Creek and the North 

 Dean, where, as alreadv noted, it forms the summit of the range. 



