Thomso:\'. — Gf^oJoyy of Middle Wai/umi and Weka Fuss Districf . 361 



The lower horizon (B) consists, in the railway-cutting 43f miles from 

 Christchurch, of upper and lower hard bands, 25 ft, and 20 ft. thick, 

 separated by about 35 ft. of sands. Both bands consist of hard brown 

 arenaceous limestone, with sandstone intercalations, forming cavernous 

 cliffs owing to the weathering-out of included fragments of derived sand- 

 stone. This phenomenon is well displayed in the cuesta between the 

 Weka Creek and the Weka Pass Stream, where the derived fragments 

 offer show clear bedding oblique to that of the enclosing rock. Fossils 

 are scarce and consist chiefly of small cup-shaped Polyzoa and barnacles, 

 but Anomia sp. and partial valves of Magadina were observed. The 

 lower bands are exposed on a clifi below the railway-cutting, between it 

 and the Weka Pass Stream, where they are intersected by a small fault 

 with downthrow to the north (Plate XXI, fig. 2). The base of the lime- 

 .stone on the northern (downthrown) side consists of a lenticular hard 

 calcareous conglomerate enclosing specimens of CucuUaea, Struthiolaria 

 tuherculata and many other gasteropods, and numerous barnacle {Balanns) 

 fragments. Unfortunately the matrix is too hard to enable satisfactory 

 specimens to be collected. The conglomerate rests upon soft grey sand- 

 stones, of which the few feet exposed show no bedding, so that the pre- 

 sence of an unconformity cannot be definitely asserted, but the presence of 

 the derived fragments of sandstone in the overlying limestone makes it 

 probable. 



In the Weka Creek the lower limestone (B) flattens out just before 

 reaching the creek-banks and is not exposed on the banks. It seems 

 probable that it is cut off by a fault with dowmthrow to the south-east. 



The third Mount Brown limestone (C) does not appear to be developed 

 in the lower part of the Weka Pass or in the Weka Creek, but is again 

 found not far below the main band (D) on the north-west face of Mount 

 Donald, and for some distance to the south-west, where in a col in the 

 cuesta it reaches the summit. It forms at the last pomt about 40 ft. 

 of hard calcai;eous sandstone, in bands of 1 ft. to 3 ft. thick separated by 

 shelly sands containing Magadina waiparensis, Anomia trigonojjsis, and 

 Pccten burnetti. A little nearer Mount Donald the bands coalesce to form 

 a shelly limestone containing an exceptionally large number of derived 

 sandstone inclusions, which weather out and give it a very cavernous 

 appearance. It contains Polyzoa, barnacles, and shelly fragments, including 

 Magadina waiparensis and Anomia trigonopsis. On the north-western "face 

 of Mount Donald the base contains a shell-bed with many casts of large 

 gasteropods. It is here underlain by sands containing concretions. 



The main Mount Brown limestone (D) forms, as already mentioned, 

 the crest of the watershed south-east of the Weka Pass. It is divided by 

 a persistent bed of sand, which outcrops just below the crest on the Weka 

 Pass side, and yielded Pachymagas cottoni n. sp. and Waiparia abnormis. 

 This limestone crosses the railway-line in the cutting 43 miles 21 chains from 

 Christchurch. At the northern end of the cutting there is about 35 ft. of 

 sands exposed below the lowest bed of limestone. These sands contain 

 occasional shells, including Ancilla pseudaustralis, Pecten huttoni, and very 

 fragile shells of Crepidula sp. Immediately below the lowest limestone 

 bed is a thm bed of broken shells, including Anomia trigonopsis and 

 Glycymeris sp. The lowest limestone bed is 5 ft. thick. It is succeeded 

 unconformably by 25 ft. of sands, containing many small derived pieces of 

 sandstone, and yielding Anomia trigonopsis. Then follows 3 ft. of lime- 

 stone, succeeded by another 25 ft. of sands. These are succeeded by the 



