Thomson. — The Gem Gravels of Kakanui. 489 



in the blasting to which the stone is subjected in quarrying, the 

 matter inside and around the shells is shattered, and allows the 

 arms to be exposed by picking. The following fossils were 

 obtained, bearing out Mr. McKay's reference to the genera : 

 Liothyrina (Terebratula), n. sp. ; Notothyris (Terebratulina) su- 

 essi ; Magellania lenticularis ; Rhynconella squamosa ; Terebra- 

 tella, n. sp. ; Pecten sectus ; Pecten hutchinsoni ; Ostrea, sp. ; 

 Pleurotomaria tertiaria ; and Aturia australis. This limestone, 

 from its pure nature and hardness, is well adapted for burning 

 for lime, and is used for that purpose. On the beach it is softer 

 and contains more impurities of the nature of volcanic - ash 

 inclusions. 



The limestone on the beach has at the south a dip in a 

 northerly direction, but it becomes flatter to the north and then 

 dips to the south, thus forming a syncline. It is covered, 

 wherever marine denudation has not denuded it, with a layer 

 about 6 ft. thick of glauconitic greensand containing many 

 fossils. The following were obtaii^d : Isis, n. sp. ; Graphu- 

 laria, sp. ; Magellania sinuata ; Turitella, sp. ; and Fusus, sp. 

 (casts) ; Dentalium mantelli ; Pecten hutchinsoni ; numerous 

 echinoid spines, and sharks' teeth. The limestone is underlain 

 to the north by the " mineral breccia," which is here finer than 

 on the first exposure. 



The general relation of the foregoing section is seen in the 

 diagrammatic section (Section I) on p. 485. 



Captain Hutton, in a paper on the " Geology of North-east 

 Otago," * refers thus to these rocks : ; ' Kakanui Volcano : The 

 Kakanui River runs into the sea between two low hills formed 

 of scoriaceous sandstone overlain by the Ototara limestone, here 

 generally more compact than usual. The sandstones of the 

 northern hill form a periclinal curve, which extends across the 

 river so as to include the rocks seen in the river-bed between 

 the bridge and the sea." On comparing the sections it will be 

 seen that the folding is rather more complex than he has indi- 

 cated. 



The cliffs on the Waiareka River call for little special detailed 

 mention. They are mostly formed of the " barren breccia," and 

 exhibit a great deal of irregularity in stratification, perhaps due 

 to current bedding. In one place a few fossils were found, but 

 they were too weathered for identification. The " mineral 

 breccia " contains all the minerals found in the first exposure, 

 and biotite in addition. The breccia is slightly less coarse than 

 at the other exposure, the largest fragments being 75 mm. in 



* Trans. N.Z. Inst., 1886, pp. 415-30. 



