98 
The N.Z. Journal of Science and Technology. [April 
the angle of inclination of the beds now is. This surface of deposition 
was in all probability the peneplain which remained after the Maitai beds 
were folded, raised, and eroded, and which has formed the basement on 
which the Oamaru series has been laid down over a considerable area in 
the southern and central portions of New Zealand. 
In their lower levels the beds consist of sands, sandy clays, and fireclays, 
associated with seams of brown coal; but above the coal-bearing horizon 
the amount of sand increases till it becomes the only constituent of the 
beds and is cemented into a true sandstone, typically developed in the bluff 
Fig. 4. —Slip west of Alum Creek, showing coal-beds with interstratified sands and 
fireclays. The seams which are being worked are lower down, below the 
base of the picture. [Photo, R. Speight. 
facing Broken River. The series is closed with greensands, which are well 
developed in Iron Creek but show nowhere in the sections on the main 
stream. 
The clearest idea of the relationship of the beds can be obtained from 
the study of the exposures in the vicinity of Alum Creek, and therefore 
these will be described first, and other localities will be taken in order. 
(a.) Descriptions of Sections. 
Alum Creek and Bushy Creek (figs. 3 and 4).—The lowest beds of the 
series are well displayed on the face of the bluff just above the inflow of 
Alum Creek, but they are quite inaccessible, so that a close examination 
cannot be made of them. The following beds are, however, clearly 
exposed :—- 
(1.) Grevwacke, much weathered. 
(2.) Sands and sandy clays with thin layers of coal; in the lower part 
regularly bedded, but in the higher part with irregular bedding, 
the coal-seams lying at varying angles. The strike is north-west, 
and the dip south-west, but some beds dip south-east without 
disturbing the general stratigraphical arrangement. 
