90 PRESIDENT S ADDRESS — SECTION C. 



stone is from 60 to 100 feet thick, and from it have been obtained 

 about a score of molluscs and three brachiopods. Chapman (1918) 

 has recognized among the, sharks' teeth Isurus, Lamna, Odont- 

 aspis, Carchnrodon, and the fish Scomhrodupea, together with 

 Foraminifera, and these incline him to consider the beds as of 

 Eocene Age. Of the same age also may be the limestone in the 

 Trelissick basin, though it has long been considered as the equi- 

 valent of the Amuri limestone. It is lithologically sometimes in- 

 distinguishable from the Amuri limestone, though usually more 

 marly. It rests upon sands and greensand about 2,000 feet thick, 

 with some volcanic ash, near the base of which is the Senonian fauna. 

 Marshall (1916) showed that the limestone was in part foramini- 

 feral, and in other portions contained fragments of echinoderms, 

 polyzoa, and Lifhothamniuvi. Speight (1917) considers that both 

 types of limestone belong to the one band. Thomson (1917) 

 showed that there was a bed of calcareous tuff in the upper part 

 of the limestone, containing Oamaruian mollusca, with a small 

 percentage of recent forms. Speight (1917) extended the list con- 

 siderably, while concurring that they indicated an early Tertiary 

 age. Chapman's studies of the foraminifera have led to the 

 tentative conclusion fiat the rock is " probably Eocene." (Fide 

 Thomson 1920, p. 386.) Following upon these beds are the more 

 normal Tertiary deposits. In the Kaikoura district the Weka 

 Pass stone is overlain, with apparent conformity, with a forma- 

 tion known as " the grey marls,"* a series of sparsely fossiliferous 

 mudstones, about 300 feet thick, passing up into pebbly bands. 

 " The presence of thick beds of mudstone following limestone is 

 evidence of a gradual sea retreat, causing renewed denudation of 

 the thick soil mantles accumulated on the coast of the Middle 

 Notocene sea." In the Waipara district the corresponding beds are 

 much thicker. The contact between the Weka Pass stone arid "the 

 grey marls" has here been claimed, at one time by Park (1905), 

 to' be an unconformity, Morgan (1916) concurring in so- far as re- 

 gards the Kaikoura district only. Speight and AVild (1917) believe 

 the conformity to be absolute. Thomson (1919) holds that there 

 was a shallowing of the sea, with oscillations, during which " the 

 grey marls," and several bands of the Mount Brown limestones, 

 were deposited with intraformational unconformities. He has dis- 

 cussed the faunal characteristics elaborately with reference to the 

 sequence in the Oamaru district (shown on Table IV.), and.con- 

 cbides that " the grey marls " and Weka Pass stone are coeval 

 with the lowest marine beds at Oamaru, and that the three lime- 

 stones which follow are resDCctively to be correlated with the 

 limestone of Oamaru, and the twO' sncceedins: stages in that 

 district. The evidence against the correlation of the jAmuri lime- 

 stone and that of Oamaru seems now to be strong. The highest 



* An <infortiinatp tprm for a formational name, since grey maj-ls of various ages occur 

 in the younger rocks of New Zealand. 



