358 Transactions. — Geology. 



common in the conglomerate, but, like the granites, they are 

 found in varieties of all degrees of texture. The colour of the 

 hornblende is dark bottle-green, and of the felspar white or 

 grey. In the finer-grained varieties these minerals exist in 

 about equal proportions, giving the appearance of a black rock 

 speckled with white. In the coarser varieties the hornblende 

 predominates, and occurs in large irregular masses, enclosing 

 comparatively large confused crystals of orthoclase. 



No fossils were found in the conglomerate, but the pebbly 

 limestone immediately overlying it contains numerous marine 

 forms, chiefly corals, mixed with small angular fragments of 

 sandstone, granite, and quartzite. The sandstone, which was 

 found in situ at the falls, has all the characteristics of the 

 Jurassic sandstones at Kawhia. Its presence as large and 

 small blocks in the granite conglomerate proves conclusively 

 ■that the conglomerate belongs to a later formation, while the 

 small angular pieces of granite and sandstone contained in 

 the pebbly beds overlying the conglomerate also prove that 

 these beds are younger than the conglomerate. From these 

 facts it may be inferred that the materials forming the con- 

 glomerate accumulated on a broken rocky shore-line, being 

 the detritus derived by a Cretaceous torrent from the erosion 

 and destruction of a wide land-area, of which no trace now 

 remains. The former existence of a large land-surface in this 

 region, composed principally of granites and other crystalline 

 rocks, fringed by a mantle of Middle and Lower Secondary 

 rocks, and subject to the erosion of rivers with great trans- 

 porting-power, is conclusively established by the presence and 

 composition of the conglomerate. The probable direction of 

 the extension of this old submerged continent is not so easy 

 to determine. It is perhaps permissible to suppose that a 

 floor of granite and granitoid rocks extends eastwards 

 throughout the central portion of this Island and westward 

 towards Kawhia. 



In his report on Kawhia district, Mr. A. McKay mentions 

 the occurrence of a syenite conglomerate on the south side of 

 the harbour. "Whether the syenites possess a trachytic or 

 granitic character is not stated, and, as the rock called for 

 little comment, it may be judged to present nothing un- 

 common or remarkable. In view of the present discovery of 

 granites in the Waipa Valley, it would be interesting to know 

 if there were any indications of these rocks in the Kawhia 

 conglomerates. 



Granites are often of an eruptive character, and in Scot- 

 land are said to have been found of Tertiary age penetrating 

 Jurassic strata. In New Zealand no granites younger than 

 Silurian are known to exist, and, as those in the Mangaone 

 conglomerate, as well as the associated gneiss and quartzite 



