96 PRESIDENT S ADDRESS — SECTION C. 



has lately reported that this succession holds good m the Whangarei 

 district, and that two unconformities intervene between the hy- 

 draulic limestone and the polyzoan limestone.* 



South C'i this region we enter a new diastrophic province, that 

 oif the Auckland district. The basal beds rest unconformably on 

 the Meso'zoic greywacke or sandstones, and are varied in character. 

 They are sometimes coal-bearing cong-omerates, caVareous sand- 

 stones or even algal limestone, the last resting on the Neoccmian 

 plant-bearing sandstone of Waikato Heads. They are followed 

 by tuffaceous sandstones with some interbedded volcanic material, 

 the Waitemata beds, passing southwards into marls, blae sand- 

 stones, and impure limestones. The scanty fauna of foraminifera, 

 polyzoans, and mollusca is of Oamaruian character. These beds 

 were slightly flexed, faulted, and partially planed, and upon them 

 were deposited fossiliferous marine strata, m which Bartrum 



(1919) has found an extensive fauna containing 62 per cent, of 

 recent species. Columnar basalts and agglomerate rest on these, 

 and are succeeded by " Pleistocene " fluviatilei silts and dune- 

 sand. This important "Miocene-Pliocene" unconformity m<ay 

 bo traced southwards into the Taranaki province. Here the 

 Mesozoic greywackes are discordantly overlain by grit and car- 

 bonaceo'Us shale covered by limestone, passing upwards, into clay- 

 stone, succeeded by massive sandstones and the coal-measures of 

 the Mokau River, remarkable as being one of the few instances 

 of Teritary coal-measures overlying marine beds that have been 

 recorded in New Zeialand. These limestones are of Oamaniian 

 age. Massive sandstones, probably to be correlated with the 

 " Pliocene " fossiliferous rocks mentioned above, and alsO' with the 

 Mokau coal-measures, rest disordantly upon thisi Oamaruian 

 series in North Taranaki (Henderson 1918), but, near New Ply- 

 mouth, the latter are covered by agglomerates, &c. , and the later 

 volcanic rocks around the eruptive centre of Mt. Egmont (Clarke 

 1912). Very widespread, also, are the rhyolitic tuffs in northern 

 Taranaki and tho neighbouring region, which appear, however, 

 to have been derived from thei eruptions in the centre of the 

 island. They form a thick covering lying unconformably on the 

 Tertiary marine rocks and coal-measures, but have been deeply 

 dissected. 



A more extensive series of unconformities m the Notocene suc- 

 cession has recently been described by Henaerson and Qngley 



(1920) in the Gisbome district. The basement rocks of greywacke 

 are beyond the regions mapped by the above authors, and the 

 oldest rocks visible in the Gisborne area are a series of shales 

 greensinds, limestones, and clavstones, containing Innceramiis and 

 belemnites. to which may be pssiened tentatively a Senonian age. 

 They are decidedly more dislocated than the overlying Tertiary 



* Private communication. 



