350 Transactions. 



Hills, Waipara, and Amuri Bluff, is associated with marine reptiles and 

 belemnites and ammonites — i.e., free-swimming forms. 



(3.) All the remaining horizons indicate a Tertiary fauna, the oldest- — 

 i.e., the tuffs interstratified in the marls at Coleridge Creek- — containing 

 only 19 per cent, of Recent species, while the higher beds contain as follows : 

 The tuff under the limestone at the Porter River, 7 species out of 9 ; the 

 tuff bed below the limestone in Broken River, 11 out of 24 ; the tuff bed 

 between the limestones near the mouth of the Thomas River, 33 out of 87, 

 or 38 per cent. ; the tuff bed under the limestone at Whitewater Creek 

 contains 1 1 out of 29 species ; the shell bed at the fall of rock yields 21 

 out of 66 — i.e., 32 per cent. ; while from the higher beds in the Thomas 

 River and Whitewater Creek, out of 42 species 13, or 31 per cent., are 

 Recent. 



The low percentage of Recent forms in the tuffs interstratified in the 

 marls at Coleridge Creek is very significant, as it indicates a lower Tertiary 

 age for these beds — granting that we can rely on percentages of Recent 

 forms as an accurate basis for age-determination — whereas the higher beds 

 contain a percentage that would lead one to think that they were mid- 

 Tertiary. There is, however, no regular increase in percentages as higher 

 beds in the series are considered, a fact perhaps due to the conditions not 

 favouring the entombment of a representative fauna, or, if it has been 

 preserved, it has not been thoroughly examined or collected from. Several 

 well-marked and distinctive forms are, however, persistent right through 

 the series. There is no indication of a distinct faunal break from the tuffs 

 under the limestone up to the highest beds from which fossils have been 

 recorded. There is, on the other hand, this low percentage of Recent forms 

 in the tuffs interstratified in the marls, and a clear faunal break between 

 these beds and those containing a Cretaceous fauna, although the flora 

 associated with this is undoubtedly Tertiary. There is, however, no evi- 

 dence of the existence of a physical break between these marls and the 

 oyster bed with its Cretaceous fauna, and this opinion has been held by 

 every authority who has examined the section- — even Hutton agrees with 

 this ; and, further, the last-named authority even agrees that there is no 

 physical break up to the top of the lower limestone : nevertheless the tuffs 

 underneath it undoubtedly contain a Tertiary fauna. This is one of the 

 most important points brought out by a consideration of the locality, and it 

 strongly supports the contention urged by Marshall, Speight, and Cotton, 

 1910 (Joe. cit.). and later by Marshall alone, as to the physical conformity of 

 our Cretaceous and Tertiary series.* 



The two chief explanations put forward to account for the association 

 of Cretaceous and Tertiary forms in a conformable series are — (1) That 

 the Cretaceous forms survived into the Tertiary era in this region after they 

 had disappeared from other parts of the world, perhaps owing to their having 

 been cut off by land barriers from competition with other forms, just as sea 

 barriers enabled the different archaic forms of land-animals to persist on the 

 land in this part of the world long after they had become extinct elsewhere ; 

 (2) that owing to the slow deposition of the marine beds in late Cretaceous 



* P. Marshall, The Younger Rock Series of New Zealand, Geol. Mag. (n.s.), dec. v, 

 vol. 9, 1912, p. 314; The '• Cretaceo-Tertiary " of New Zealand, Geol. Mag. (n.s.), dec. v, 

 vol. 10, 1913, ]). 286; New Zealand and Adjacent Islands, Handbuch der regionalen 

 Geologic, Hand 7, Abt. 1, Heidelberg, 1911, p. 28. 



