Speight. — The Older Gravels of North Caiitcrhvry. 273 



towards the base of the cliff points to their having been deposited in 

 shallow water in close proximity to a shore-line, and not on a land-surface ; 

 but at the higher levels the stratification becomes more indistinct and the 

 pebbles become coarser and more subangular in shape, so it is almost certain 

 that the closing beds of the series were laid down on a land-surface. The 

 presence of lignite in the lower beds clearly indicates estuarine or deltaic 

 conditions. 



It should be noted that on the high banks of the Grey River there is 

 a still more recent series of gravels belonging to the history of the stream. 

 They are similar in lithological features to the gravels of the Kowai series, 

 but they are neither so well stratified nor so well cemented. They are 

 undoubtedly river and not sea deposits. Where contacts can be seen they 

 are easily differentiated, but elsewhere, especially on the lower slopes of the 

 downs, it is difficult to separate them from the upper members of the lower 

 set of beds, which were also laid down on a land-surface. 



Grey River, West Branch. 



The general stratigraphy of the beds in the basin of the western branch 

 of the Grey River is similar to that in the eastern. The following is a 

 general description of the strata exposed above the greywacke as disclosed 

 on the sides of the gorge of the stream : — 



1. Sands and greensands. 



2. Limestone, full of bryozoan remains, but only a few feet thick in the 



gorge of the stream, thickening, however, to the east and to the 

 west. There is a marked difference in the features of this lime- 

 stone as compared with that in the eastern branch, and as they 

 are in apparent continuity it might be assumed that the stone 

 in the western branch represents a shallower- water facies. I am 

 by no means certain that this is the true explanation, and the 

 question of the identity as regards their stratigraphical position 

 must be reserved for further investigation. 



3. Marls, greenish in colour, with rounded concretions and concretionary 



bands, passing up into greyish sands with fragmentary fossil 



shells. 

 In the river these beds strike E. 25° S. and dip south at an angle of 30°, 

 but they have suffered some deformation, and the strike changes to north- 

 east on the ridge between the two branches of the Grey, and also as the 

 beds are traced round to White Rock and the Okuku River. The upper 

 surface of the sands was distinctly eroded before the next bed was laid 

 down. This consists of a heavy band of cemented gravel. The following 

 beds are then encountered, in ascending order : — 



4. Gravel bed just referred to. 



5. Sandy clays and gravels. 



6. Sandy clay and carbonaceous shale, repeatedly alternating. One bed 



of shale is from 12 in. to 18 in. thick. 



7. Sandy gravel, well cemented with iron oxide. 



8. Greenish-grey sands, sandy shales, and gravels, rapidly alternating, 



totalling over 200 ft. in thickness, the strike gradually becoming 

 east-north-east, and the dip flattening out from 30° to 10°. 



9. Gravels, sandy and with occasional thin layers of sandy clay, lying 



flat or with slight dip to the south-east. These are at least .500 ft. 

 thick, and are well exposed on the ridge between the western 

 Grey and the stream near the White Rock Station. 



