Wilson. — On the Oxford Chalk Deposit. 275 



The dip of the chalk cannot be absolutely made out, as it is 

 so much obscured by bush and alluvium ; but from observations 

 I made upon the greeusand by which it is underlain, there can, 

 I think, be little doubt but that its dip is about 27° to the 

 south-east. This, too, is the conclusion Mr. McKay comes to. 

 Beneath the chalk, as I have just noticed, is a bed of greensand ; 

 above it is a layer of basaltic rocks, whose decomposition appears 

 to have given rise to the soil bearing the bush covering the 

 whole hill. At the point marked L in the accompanying 

 diagram, and within a few yards of the chalk section, what 

 appears to be a dyke of this basalt has assumed a columnar 

 form in cooling. 



Mr. McKay, from his report, seems to have had some doubt 

 as to whether the chalk (?) outcropping at L was the exact 

 equivalent of that at M. Until the bush is further cleared, 

 exposing other sections, this of course cannot be absolutely 

 determined. I was, however, fortunate enough to obtain speci- 

 mens of Pecten ivilliamsoni* from each section. 



P. williamsoni, I may remind you, is found at Aotea and 

 Eaglan, North Island ; Kaipuke and Tata Cliffs, Nelson ; Black 

 Birch Creek, north side of Hurunui Plains; and from the 

 Curiosity Shop, on the Bakaia. The other fossils from each 

 section, so far as my investigations have carried me, differ con- 

 siderably from each other. 



At L I obtained (2nd) P. fischeri.\ This fossil was originally 

 described from Papakura, near Auckland. Since then it has 

 been found at Port Waikato, Oamaru, and Weka Pass. 



3rd. Cristellaria (Robulina) cultrata, D'Orb., var. antipoclum, 

 Stache.j Hitherto only found at Eaglan. 



4th. Several varieties of Pecten hitherto undescribed. The 

 presence of these fossils, so characteristic of the Oamaru System, 

 leaves no doubt as to the age of the chalk. 



At M, where the chalk is much freer from silica, I found, it 

 composed very largely of Foraminifera. A section ground thin 

 and placed under the microscope exhibited many coccoliths. 

 The only large fossil, however, that I have been able to discover 

 at this outcrop, in addition to Pecten williamsoni, is a rather 

 abundant brachiopod, hitherto undescribed, but apparently 

 allied to Terebratulina lentiadaris, Tate. 



The presence of the Foraminifera and coccoliths at once point 

 to the conclusion that the deposit is a true chalk, and not a mere 

 limestone ; but the following comparison between its chemical 

 composition and that of the English chalk leaves no doubt upon 

 the subject : — 



* " Voy. Novara," plate ix., fig. 11, p. 50. 



t Zittel, plate ix., figs. 1 and 2, p. 53. 



J Palaeontology of " Novara Expedition," plate xxiii., fig. 30. 



