346 Transactions. — Geology. 



to the south-east in the direction of Wanganui is small, as the 

 blue clays exposed in the Shakespeare Cliff are not less than 

 30ft. high, and they are about the same height on the beach 

 between Castle Cliff and Kai-iwi. If we suppose a line running 

 along the top of the blue clays from the Kai-iwi mouth or the 

 coast cliffs to the Kaiwaiki quarries, and another from where 

 the clay-sands terminate on the beach towards Castle Cliff to 

 Shakespeare Cliff, there will be actually represented the old 

 slope or plane of denudation over a given area. On this area 

 calcareous and fossiliferous sands were deposited, such as are 

 now exposed in Shakespeare Cliff and in other places along the 

 left bank of the Wanganui Eiver as far as Landguard. In 

 some places the sands have been denuded, and their places are 

 now occupied by shingle-conglomerates and other succeeding 

 beds such as have already been enumerated as being exposed 

 in the several places along the bank of the river. Now, the 

 area between Shakespeare Cliff and the sea, including the spot 

 on which the Town of Wanganui is built, contains traces that 

 it also was, at a comparatively recent date, capped with shingle- 

 conglomerates and pumiceous swamp-clays. In the direction 

 of St. John's there are shingle-conglomerate beds of great 

 thickness, and they appear to be the remnants of a line of hills 

 that once extended from Aramoho to the coast. Whether the 

 area now covered by dunes and shingle-conglomerates is one 

 of denudation or of depression I do not know ; but evidence is 

 in favour of a combination of the two. If the former be the 

 sole cause of the changes, then we may be sure that the blue 

 clays of Shakespeare Cliff are not far below the surface, and 

 artesian water would hardly be expected or possible under 

 such conditions. But if the area under notice is one of depres- 

 sion — that is, if the country between Shakespeare Cliff, Land- 

 guard, and the cliffs along the coast in the direction of the 

 Kai-iwi mouth be one of depression — then the conditions exist 

 of a catchment- or water-basin, and the prospects of an artesian 

 water-supply are good. Every deposit covering the hills in 

 the immediate vicinity of the town, and to the north-west and 

 north of the district, is a great water-carrier, except the clay- 

 beds, and the general slope of the beds from the Kai-iwi 

 Stream and the Kaiwaiki quarries is towards Wanganui. 



These are essentials to the existence of an artesian water- 

 supply; but there is yet another essential — viz., the existence 

 of a basin or a depression-like area having such an arrange- 

 ment of beds that water may drain into them, and be focussed, 

 as it were, to a given place, somewhat like the depression for 

 the gra,vy in a good grill-iron. The lower bed must be imper- 

 vious, or nearly so, to water, and it must be channelled or 

 troughed somewhat like the blade of a long-handled shovel, 

 as used by navvies. In other words, whilst there may be a 



