Mahsiiall, Si'HitniT, Cotto.n. — Y(>itii(/( r l'nch--srrl(x of N.Z. 403 



great thickness in the Waipara, and at Amuii JJlufI" (JOO ft. We are not 

 yet fully acquainted witli the coiditions under Avhicli greensand is formed, 

 hut the latest information shows that it is deposited near a steep coast 

 wliere the water is particularly clear and perhaps 500 fathoms deep.* Such 

 conditions evidently favour slow accumulation, and this idea is supported 

 hv the abundance of sharks' teeth in th(> greensand in many localities. 



(iv.) Limestones. — The limestones vary much in thickness and in nature 

 The limestone at the Amuri Bluff is formed mainly of isolated chambers 

 of Glohigerina. It is here little more than a chalk. At other places the 

 larger species that live on the sea-floor are more prominent. This is veiy 

 noticeable in the more sandy varieties at Dunedin. and still more con- 

 spicuously at the Mokau, where the limestone contains also an abundance 

 of the remains of the calcareous alga Lithothatuniutn. At Oamaru the 

 Imilding-stone consists mainly of phites of echinoderms, with Pohjzoa and 

 Foraminifern. Near Cape Farewell coral is the chief organism in it. The 

 deposition of the limestone must represent a considerable lapse of time, 

 for at Amuri Bluff it is 650 ft. thick, and its nature there shows that it 

 formed with extreme slowness. 



In all places it is uncontaminated with sediment, except quartz-grains. 

 Its wide occurrence and penetration into many mountain-gorges sho\\s 

 how much of the present land-area was submerged at this time. 



Above, as below, the limestone passes in many places into a greensand, 

 but this upper stratum is relatively thin when compared with the lower on<', 

 and this, of course, suggests that the upward movement was more rapid 

 than the downward movements. 



The grey marls are very thick in some places, though it is quitch oftc n 

 the case that they have been eroded off tlie surface of the limestone. Their 

 absence in the southern part of the South Island is perhaps to be explained 

 in this way, though it is quitch possible* that they were never deposited in 

 that part of the country. The grey marl consists largely of minute scales 

 of mica, though these are mixed with much calcareous matter. 



The Mount Brown and Pareora beds that lie on the grey marls are 

 relatively coarse detrital formations, and may have; been deposited much 

 more rapidly than the lower beds of the series. 



Taking the series as a whole, we think that the time requir<'(l for its 

 deposition was sufficiently great to allow of considerable faunal cliange to 

 take place, and specially when a, possible previous isolation is borne hi 

 mind. We regard it as almost sufficient in itself to account for the im- 

 portant differences between the fauna of the lowest and highest membei'S 

 of tliis conformable sequence. 



V. CORRRLATION OF Mp^MBERS OF THE SkRIES. 



As previously stated, we believe that there is complete evidence of 

 stratigraphical conformity of the rock-series hert; described. It is, however, 

 a fact that the lowest member of the series in some localities, such as Waipara 

 and Amuri Bluff", is much older than that of Kawhia and of Oamaru 

 (Livingstone). This has always appeared to justify the division of the series 

 into different geological systems, which was based on the dift'erence in 

 faunal characters of the various members of th • series at Waipara, and 

 supported by the stratigraphical breaks described in the series by different 



* Murray and Lee. 



