34 Transactions. 



again rises tlie Ngapara tableland. The latter is a well-preserved part 

 of an elevated plain of denudation whicli was formerly continuous to the 

 coast-line, but has been more dissected in the neighbourhood of Oamaru, 

 tliough it is still recognizable there. This old plain truncates the Tertiary 

 rocks around Ngapara at a low angle, and it is probable that, under the loess 

 deposits which cover it, remnants of the Hutchinson Quarry and Awamoa 

 beds are preserved, though they have not so far been described. Near 

 Ngapara itself the plateau is cut across the Ngapara limestone, which 

 runs thence to the Awamoko Eiver and the Waitaki Valley. There can 

 be no doubt that the Ngapara limestone was formerly continuous across 

 the Waiareka Valley with the Ototara limestone. The rocks underlying 

 the two limestones are not, however, the same. The Ngapara limestone 

 is underlain by greensands of considerable thickness, and these pass down 

 into quartz sands Avithout glauconite, interstratified with grits and con- 

 glomerates and a seam of brown coal. The succession thus exactly 

 resembles that at Waihao. The Ototara limestone, on the other hand, is 

 underlain opposite Alma by volcanic breccias of no great thickness, and 

 these again by a deposit of diatomaceous earth, which in turn rests upon 

 a considerable thickness of volcanic tuffs and lavas. The latter at Enfield 

 rest on greensands, which can be traced thence at various points through 

 Windsor to Ngapara. The volcanic series underlying the Ototara lime- 

 stone in the Waiareka Valley has long been known as the AVaiareka series, 

 which, strictly speaking, must include the diatomaceous earth. The dif- 

 ference between the succession at Enfield and that at Ngapara is due 

 mainly to the volcanic conditions existing during deposition at the former 

 place, though a local subsidence, perhaps correlated with the volcanic 

 activity, seems necessary to explain the formation of the diatomaceous 

 earth, regarded by Hinde and Holmes as a deep-water depooit. The 

 Ngapara succession represents more normal conditions of marine deposi- 

 tion, such as prevailed in the Waitaki Valley, Waihao, and other South 

 Canterbury localities. 



For the above-described succession at Oamaru the following stage 

 names are suggested : — 



Top. Awamoa beds . . . . . . Awarnoan ) 



Hutchinson Quarry beds and concretionary ^ Upper Oamaruian. 



band . . . . . . . . Hutchinsonian ) 



Ototara limestone . . . . . . Ototaran . . Middle Oamaruian. 



Waiareka tuffs and Enfield-Windsor green- \ 



sands = Ngapara greensands . . Waiarekan \ y ^ 



^ , 1 1 i. J Y Lower Oamaruian. 



Coal-measures, sands, conglomerates, and 



coal-seams . . . . . . Ngaparan ) 



All ambiguity caused by the use of the terms " Pareora series," 

 " Pareora fauna," &c., may be avoided by the adoption of " Awamoan " 

 for the uppermost stage of the Oamaruian. On grounds of strict priority, 

 the name for this stage should perhaps be founded on the Onekakara 

 formation of Mantell (1850) ; but although the blue clay of All Day Bay, 

 which Mantell included in that formation, and from which he described 

 its fauna, is undoubtedly Awamoan, there is considerable doubt whether 

 the Onekakara (Hampden) beds are not really Waiarekan, as McKay (1884) 

 supposed, since their stratigraphical relationship to the Ototara limestone 

 is not clear, and all that is known about them palaeontologically is that 

 they contain the " Pareora fauna." 



