Thomsox. — Geology of Middle WaijJara and Weka Pass District. 365 



The heds are covered unconformably by the Kowhai gravels, the 

 junction being' clearly seen in a tributary draining from Mount Brown. 

 Mr. R. Speight informs me that a very good fossil-locality for the Greta 

 beds has been discovered recently in the north branch of the Kowhai Eiver. 



The first cuesta behind that of the main Mount Brown limestone (D) 

 on the Mount Brown road consists of a fine conglomerate containing sparse 

 pebbles of quartz, greywacke, and jaspers in a white calcareous cement, 

 and lies about 100 ft. above the main limestone. Whether this represents 

 the uppermost Mount Brown limestone (E), or, as seems more probable, 

 the base of the Greta series, remains uncertain. A series of alternating 

 sands and shelly gravels ca]>ped by a hard coarse conglomerate forms the 

 next cuesta, lying at least 100 ft. above the former. The sliells represented 

 are chiefly Glycymeris laticostata, Crepidula gregaria, and C. monoxyla ; but 

 I collected also Antigona zelandica, Chione stutchburyi, Dentalium solidum, 

 Dosinia greiji, D. suhrosea, Ostrea nelsoninna, Spisufa aequilateralis, and 

 Verconella mandarina. 



Waipam River — For some distance below the outcrop of the main 

 Mount Brown limestone no Notocene beds are exposed on the north bank 

 of the Waipara River, and the base of the Greta series does not outcrop 

 at this point. The lowest beds seen lie on the south bank, at the bend of 

 the river opj)Osite the end of the cuesta running down from Mount Brown 

 (but on the oj^posite side of the Boby's Creek fault), and consist of sand- 

 stones with concretions, followed by mudstone, on which rests 20 ft. of 

 fine gravelly and sandy shell-beds containing Cerifhidea bicarinata, Tellina 

 deUoidalis, Verconella dilatata, Venericardia difficilis, and other species too 

 fragile to collect. This is followed by soft greenish mudstones yielding 

 Ancilla mucronata, Cerifhidea bicarinata, Chione yatei, Cominella adspersa, 

 C. quoyana, Crepidula gregaria, Mactra discors{'\), Ostrea angasi, Struthio- 

 laria papulosa, and Tellina deltoidalis. Above this occur shelly conglome- 

 rates 6ft. thick, containing Ancilla australis, A. pyramidalis, Barnea similis, 

 ■ Sigapatella novae-zelandiae, Cerithidea bicarinata, Chione chiloensis, C. yatei, 

 Ischnochiton maorianus, Cominella quoyana, C. adspersa, Crepidula costata, 

 C. striata, C. monoxyla, Diplodon zelandica, Dosinia greyi, Lapparia corric- 

 gata (?), Lutraria solida, Mangilia sinclairi. Modiolus australis, Musculus 

 impactus^ Ostrea angasi, Rissoina vana, Seila chathamensis var., Verconella 

 dilatata, V. mandarina, Terebra fristis, Trocmis tiaratus, Trophon corticatus, 

 Venericardia . purptirata, Vohita arabica, Volutospina huttoni psewlorari- 

 spina {\). To these about 20 ft. of mudstone succeed, containing fossils 

 similar to the lower mudstones ; then a further 10 ft. of sandy and gravelly 

 shell-beds (mostly Ostrea and Venericardia with Anomia huttoni), about 

 25 ft. of nmdstone, another Ostrea aiid Venericardia shell-bed, 12 ft. of 

 muddy sands, 10 ft. of yellow sands, and 10 ft. of gravels', after which the 

 section ends. 



About a quarter of a mile down-stream on the north bank there is an 

 exposure of mudstones with fossil wood resting on sandstones and shelly 

 conglomerates. The mudstones yielded Arcopagia discidus, Cerithidea 

 bicarinata, Chione ohiloensis, Crepidula monoxyla, Dosinia greyi, D. sub- 

 rosea, Modiolus australis, Ostrea angasi, and Tellina deltoidalis. These are 

 succeeded by a muddy sandstone. After a gap in the succession further 

 sandstones and shelly conglomerates appear. 



A boulder obtained from the river-bed farther down by a settler con- 

 contained Ostrea ingens. The matrix was a pebbly calcareous sandstone, 

 quite similar to some of the hard bands of the Greta beds forming small 

 cuestas on the slopes towards the Deans. 



