Morgan. — Reconh of Unconformifiea in Neii: Zealand. 7 



statement, contributed to Marshall, Speight, and Cotton's paper of 1911 

 (47, pp. 396-99), appears to dispose of the unconformity believed by Hutton 

 to exist between the Aotea (Papakura) Series and the Waitemata rocks. 

 No evidence other than Hutton's concerning the supposed discordance 

 between the Aotea Series and the brown-coal measures is available, but 

 apparently it was observed by him at a single point only, in fault-broken 

 country (19, pp. 246, 247), and therefore additional data are necessary before 

 it can be accepted. On the other hand, it cannot be rejected without further 

 investigation. 



III. GiSBORNE ~ East Cape District. 



In 1877 Hector distinguished the Tawhiti beds of supposed Lower Ter- 

 tiary age from the Turanganui Series of Cretaceo-tertiary age, and gave 

 sections showing unconformities between the two sets of rocks (3, pp. xvi 

 and xvii ; map and sections opposite p. xvi). His sections also show a strong 

 discordance between Upper Tertiary and Cretaceo-tertiary rocks in localities 

 where the Tawhiti becls are absent. McKay, in the same year, described 

 evidence of unconformity at several points in a post-Cretaceous horizon, 

 his strongest point being that at Whareponga, " behind the church, an 

 unconformable junction between the marls with concretionary masses and 

 the younger rocks is seen " (3, p. 121). In 1887 McKay perceived uncon- 

 formity between the Tawhiti beds and the Turanganui Series at Akuakua 

 (Akuaku), and between the former rocks and the Waipiro Series at Riparua 

 (Reporua) (13, section on p. 218). Inland he discovered thick beds of con- 

 glomerate containing igneous boulders in the Lower Miocene rocks of the 

 Ihungia and Mata Rivers, but so far as can be judged from his report did 

 not regard the occurrence as significant of stratigraphical break. In 1901„ 

 however, he placed an unconformity in the Gisborne district between rocks 

 of supposed Cretaceous age and undoubted Miocene strata. Conglomerates 

 similar to those just mentioned, and containing boulders of limestone derived 

 from the underlying strata, he considered to mark the base of the Miocene 

 (36, p. 24). J. H. Adams, however, as the result of a detailed survey over 

 the limited area included in the Whatatutu Subdivision, came to the con- 

 clusion that the so-called Cretaceous rocks of that part of the Gisborne 

 district were conformable to the overlying Miocene s.trata, and, although 

 confirming McKay's description of the conglomerate, did not recognize it 

 as evidence of unconformity (44, pp. 12, 18-20). Marshall, as the result 

 of field examinations and of palaeontological work, confirmed Adams's 

 statements (44, pp. 21-23; see also 47, p. 393). Neither Marshall nor 

 Adams found any fossils of Cretaceous aspect in the Whatatutu district, 

 but McKay's statement that Inoceranms occurs in concretions in the bed 

 of the Waipaoa River has since been confirmed by at least two observers — 

 one a geologist of repute — -and, in addition, a belemnite has been found on 

 Waitangi Hill by Mr. M. P. Poole, of Tuparoa. During a visit to the Gis- 

 borne district in January, 1914, the writer, guided by Mr. John Mouat, saw 

 numerous specimens of Inoceramus near Motu Falls, at a point about five 

 miles from the north-western corner of the Whatatutu Subdivision. The 

 fossils occur in a dark mudstone, probably corresponding in horizon to 

 the clay shale forming the lowest portion of Adams's Whatatutu Series 

 (44, pp. 12-13). 



Summary. — -The available evidence strongly supports the presence of. 

 an unconformity below the Miocene strata of the Gisborne -East Cape 

 district. 



