1919.] Wild and Speight.—Limestones of Canterbury. 187 
Another large area in South Canterbury over which limestones are 
distributed stretches along the eastern base of the Hunter’s Hills and their 
northern continuation from the gorge of the Otaio, across the Pareora near 
Craigmore to Cave, thence across the middle course of the Opihi to just 
north of the Kakahu, in close proximity to the gorge of that river. A small 
outlier also lies near the gorge of Te Moana, and faulted outliers of the 
main limestone mass occur near Tengawai Gorge and near Fairlie. The 
beds are generally gently inclined either in open anticlines and synclines 
or lie at moderate angles against older rocks. In places, as at Otaio Gorge 
and Cannington, the inclination is steeper, probably as a result of deforma¬ 
tion owing to earth-movements either of folding or faulting against the 
older, more resistant rock-masses. There is abundant evidence of the latter 
throughout the district, causing at times parallel escarpments, as at Kakahu, 
or complete separation of the beds, as in the case of the outliers just 
mentioned, which owe their position to a major fault running north-west 
from the neighbourhood of Cave through Albury to beyond Fairlie. In 
this region, as in North Canterbury, there is a cover of late Tertiaries 
which masks the limestones, but it has been stripped over large areas, so 
that the exposures of limestone and the areas where it forms the subjacent 
rock of the soil are certainly greater. 
The limestone is generally glauconitic, and resembles the Waihao 
limestone in age and character. In places, as at Otaio Gorge, it 
takes on a facies closely resembling Amuri limestone; but this does not 
indicate an equivalence in age, but rather a similarity in the conditions of 
deposit. 
Mount Somers .—About three miles north and west of the Mount Somers 
Railway-station there is a deposit of limestone of considerable extent, and 
easily accessible, a part of it being served by a tram-line down which coal 
and lime are carried to the railway. This is of approximately the same age 
as the Waihao limestone, and much younger than the characteristic lime¬ 
stones of North Canterbury. It was in all probability laid down in close 
proximity to a shore-line, and is composed largely of fragments of shells 
and sea-urchins. The content of phosphate is, however, too low for serious 
consideration in this respect, although it is undoubtedly, from the purity 
of the rock and its easy accessibility, a valuable source of calcium carbonate 
for agricultural and building purposes. 
Glauconitic Sandstones. 
These sandstones, or greensands, as they are sometimes called, are of 
wide distribution in the Canterbury district, usually underlying the lime¬ 
stones. They are typically developed at Waihao, near Waikari, and at 
Port Robinson. They are important, since they contain a certain low 
percentage of P 2 0 5 not only distributed through the rock but concentrated 
at times into layers of phosphatic nodules. One of these layers has been 
described earlier in this report in connection with the Waihao limestone, 
which is itself highly glauconitic and approaches a calcareous greensand 
in character. Such layers of nodules are worked successfully in England 
and Belgium and northern France as a source of agricultural phosphate, 
and they are usually regarded as having been formed from the droppings 
of fish and reptiles which inhabited the seas of the Cretaceous period. 
No locality in Canterbury has up to the present disclosed a bed of suffi¬ 
cient richness to be worked satisfactorily, although the Jed River does 
