Thomson.- — Geology of Middle Waipara and Weka Pass District. 359 



conformity. Fossils are fairly plentiful, including corals and Foraminifera, 

 but the molluscs are mostly in the condition of casts. They include 

 Turritella carlottae Watson and Gorhula canaliculata Hutt. The succeeding 

 beds are not exposed, but highev up the slope loose sands are seen. 



The Middle and North Dean are composed of a yellow calcareous 

 sandstone with many comminuted shells in certain bands, and frequent 

 inclusions of a yellow-brown sandstone, which also forms separate bands. 

 This is probably the second Mount Brown limestone (B). The main band 

 (D) does not here form the crest of the range, but appears in rounded hills 

 about half a mile to the south-east. Between B and D there are sands 

 and further yellowish -white calcareous sandstones containing " fucoids," 

 barnacles, Polyzoa, and echinoids. 



The third Mount Brown limestone (C) is a yellow calcareous sand- 

 stone, about 30 ft. thick, containing in places an abundance of Magadina 

 waiparensis. It may be traced from near the South Dean to the cliffs 

 opposite the meander in the Waipara River below the gorge, but appears 

 to pass into a sandstone before the river is reached. 



Fig. 6. — Unconformity at junction of Boby's Creek and tlie Waipara River. 



The Main Mount Brown limestone (D) forms the crest of the cuesta 

 on the cliffs near the Waipara River, but higher up the hill, towards the 

 Deans, it falls back behind the crest. It is divided into tjvo parts by a 

 persistent band of sand, 5 ft. thick, which contains occasional specimens 

 of Ostrea, Anemia, and barnacles. The lower part is harder and not so 

 rubbly as the upper, and contains few fossils but barnacles. The base 

 of the upper part consists of a persistent shell-bed, 2 ft. thicks containing 

 Pectem beethami, P. hurnefti, Lima colorata, Anomia trigonopsis, and casts 

 of many other species, including Turritella. The remainder is the usual 

 red-brown rubbly impure limestone, containing an abundance of Magadina 

 browni. The main band is bent into a syncline where it reaches the 

 Waipara River (Plate XXI, fig. 1) ; the lower part consists of alternating 

 sands and calcareous sandstone, containing Pecten huttoni, while the under- 

 lying sands contain Placxmanomia sp. and Pachymagas not sufficiently well 

 preserved for specific identification'. 



On the opposite side of the river the Main Mount Brown limestone 

 (D) is exposed in a small syncline, truncated by the Boby's Creek fault. 

 It is of the usual rubbly character, and yielded Pecten burnetti, Ostrea sp., 

 Magadina browni, Rhizothgris rhizoida, and Pachymagas of the joarki series. 

 Cup-shaped Polyzoa are fairly abundant. 



