Thomson. — The Gem Gravels of Kakanui. 491 



sions, 150 mm. by 100 mm., 125 mm. by 100 mm., 175 mm. by 

 200 mm., 25 mm. by 40 mm. A basalt block 5 ft. by 4 ft. by 

 1 ft. contained — Hornblende, 75 mm. by 50 mm. ; black augite, 

 50 mm. by 40 mm. ; biotite, 25 mm. by 12 mm. ; green augite, 

 6 mm. ; noncrystalline inclusions. This large block of basalt 

 suggests proximity to the crater. It is possible that the sudden 

 changes of dip may be due to the opposite directions of dip inside 

 and outside of the crater. 



One point regarding the origin of the inclination of the 

 rocks might perhaps be discussed here. Captain Hutton in the 

 paper referred to* states his conclusion that the Ototara lime- 

 stone is the remains of several old coral reefs built up round 

 small volcanic islands near the coast, and that it retains its 

 original plane of deposition. This explanation seems to be 

 pretty well borne out by the observations on the locality, but 

 the syncline of the " mineral breccia " shown in the section of 

 the North Head requires a hypothesis of folding. 



The fossils obtained in the layers of the breccia to the south 

 were as follows : Nothothyris suessi and Waldheimia lenticularis. 

 The overlying limestone was rather glauconitic below, but passed 

 into a hard coral reef above. The surface is easily denuded of 

 the overlying greensand, and much eroded. It was formed 

 chiefly of corals, especially Flabellum circulare and Isis dactyla, 

 and Lamna, sp. The overlying greensand is very fossiliferous, 

 and contains Isis dachjla ; Isis, n. sp. ; Magellania sinuata ; 

 Terebratella, n. sp. ; and Fusus, sp. (casts). 



There was no contact here with the blue clay seen further 

 south. Captain Hutton (loc. cit.) says, " The unconformity be- 

 tween it and the underlying limestone is plainly to be seen in 

 the coast section, not only in the difference of dip, but also in 

 the denuded surface of the limestone (Section iv)." This 

 appears inconclusive, for the denuded surface of the limestone is 

 due to recent removal of the greensand and subsequent weather- 

 ing. The difference of dip is more conclusive, but, compared 

 with the general run of dips in the locality, is not very surprising. 

 Still, there is a probability of unconformity from the fact that no 

 contact is seen, and from the general flat nature of the blue clay. 

 The fossils obtained in it were Flabellum circulare, Dentalium 

 mantelli, Turritella rosea, Scalar ia rotunda, Solonell.i australis. 

 and Cucullcea, sp. A whale was also found. Of these T. rosea 

 and S. funiculata are not recorded elsewhere from the Oamaru 

 system, and go to prove that the beds belong to the Pareora 

 and not to the Oamaru system. 



* Trans. N.Z. Inst., 1886, p. 421. 



