70 The N.Z. Journal of Science and Technology. [Mar 
terrestrial facies of the higher stages of the Oamaruian and even of the 
Wanganui an. 
It would serve no useful purpose to set out here the opinions of various 
geologists as to the age of these beds as expressed in published maps and 
reports ; but it may be mentioned that the ages as there set down range 
from Cretaceo-Tertiary to Pleistocene. These correlations have been merely 
guesswork except in so far as they have been influenced by the theory 
that the beds were laid down in pre-existing depressions, which, accord¬ 
ing to Hutton’s view (1885, pp. 62, 87), were excavated by glacial erosion 
in the early Pliocene. Little or no light is shed on the subject by the 
fossils thus far reported—namely, a fresh-water mussel, some diatoms and 
leaves (Hutton, 1885, p 66), and seeds of Hakea (Marshall, 1911, p. 46). 
A study of the plant-remains in the lignite-beds might yield evidence of 
great value. 
Nature arid Extent oj the Beds .—A great thickness of these non-marine 
beds is preserved in the Central Otago depressions. They are described 
as follows by McKay :— 
“ The lowest beds are quartz grits and sands, often auriferous. Dark 
leafy shales and thick beds of brown coal are associated with these beds. 
Above them lie white marly or slaty clays, sometimes of very considerable 
thickness : these clays and marls contain fresh-water shells, fish and bird 
bones, and at places numerous fern and tree leaves. In the Manu- 
herikia Valley marly beds and occasional beds of hard stone contain as 
much as 60 per cent, of lime. These beds are either gradually succeeded 
by sands, greenish clays, and pebble beds, or suddenly by coarser gravels, 
which, alternating with beds of finer materials, compose the mass of the 
formation. 
“ Volcanic rocks are associated with these beds, stretching from Hamil¬ 
ton’s across the Taieri River to the base of the Kakanui Ranges between 
the Swinburn and Shag River near its source. These volcanic rocks overlie 
the lignites and white clays, &c., and underlie the upper or sandstone 
gravels known in the district as ‘ Maori bottom.’ ’’ (1884, p. 64.) 
Park describes the beds in the area of non-marine sedimentation as 
follows, under the name “ Manuherikia lacustrine series ” :— 
“It is typically developed in the Manuherikia Basin, where it consists 
of quartz sands and shales with lignite, sandy clays, and soft sandstone, 
followed by beds of sandstone gravel. The total thickness of the different 
strata is not much less than 1,000 ft.” (1910, p. 140.) 
The former wide extension of these strata over the areas forming the 
uplands and highlands of the present surface is proved by the occurrence 
of numerous outliers and sarsen stones. Park notes that quartz gravel 
occurs commonly on the upland surfaces (1908, p. 7). To quote McKay, 
the cover seems to have been “ all but universal over the surface of south¬ 
eastern, interior, and north-eastern Otago ” (1897, p. 113). 
A minimum idea of the thickness of these beds is obtained from the 
record of a well-boring put down on the Maniototo Plains to a depth of 
575 ft., passing through a succession of beds of clay, sand, and quartz 
grit, and penetrating finally a fine quartz gravel (Gordon, 1893). A shaft 
near the northern margin of the Maniototo depression was sunk to a depth 
of 300 ft., passing for 200 ft. through beds of “ gravel, sand, and silt 
derived from the disintegration of sandstone rocks ; while the last 100 ft. 
sunk passed through white quartz drifts of a moderately fine grain and 
