1919.] Wild and Speight.—Limestones of Canterbury. 
185 
rule that wherever the Amuri limestone and Weka Pass stone occur they 
are covered to some extent by later calcareous beds. Whereas the two 
limestones just mentioned can be regarded as a deposit laid down in the 
deep sea, these higher beds are shore or shallow-water deposits, contempo¬ 
raneous in part with the deeper-water beds, but also in part subsequent 
to them and laid down over them as the sea was shallowing towards the 
latter end of the Tertiary era. Owing to the admixture of sand, gravel, 
and other detrital beach material, they are too impure to be regarded as 
possible suppliers of phosphatic limestone. 
South Canterbury. 
The most important area of limestone stretches along the south bank 
of the Waihao River for about two miles on either side of the Waihao 
Forks Railway-station. It forms a bold escarpment facing north, along 
the base of which flows the river. Isolated patches occur to the north 
of the river near McCullough’s Bridge, and farther north still on the south¬ 
western slopes of the Hunter’s Hills. The following is a detailed description 
of the limestones met with in different parts of the area. 
Below McCullough’s Bridge, on the steep banks of the river, an 
arenaceous glauconitic limestone is exposed passing down into greensand ; 
about 20 ft. below its upper surface is a hard concretionary band, 10 in. 
to 12 in. thick, underneath a normal dark greensand. The upper part of 
this is bored with tubes, and shows irregular-shaped nodules and borings 
in the upper layer, closely resembling those found in connection with the 
nodular layer of the Amuri limestone of North Canterbury. The occurrence 
is at a lower level than the normal limestone of the locality, but it is 
a horizon from which probably phosphatic nodules have been formerly 
obtained in this district, and therefore mention is made of it. 
The point farthest east at which the true Waihao limestone was 
observed is the end of a spur of the high ground south of the river which 
stretches out into the valley about three-quarters of a mile below 
McCullough’s Bridge. At this spot a quarry was opened in order 
to obtain stone for building purposes, and it furnishes the following 
section :— 
(1.) Whitish calcareous sandstone, quarried for building, and passing 
up into— 
(2.) Glauconitic sandstone, with nodules scattered through it, the upper 
part with passage beds into the overlying formation. 
(3.) Limestone, marked by hard concretionary bands alternating with 
bands of more glauconitic character, which are softer. It is full 
of fossils, notably brachiopods and sea-urchins, and the lime¬ 
stone is largely made up of shell - fragments. There is one 
distinctly marked layer of well-rolled shell-fragments, with 
occasional rounded quartz pebbles, and the beds below this are 
richest in nodules, some of which are based on fragments of 
bone, and some are almost pure phosphorite in appearance. 
Worm-borings are very evident in this layer. 
The layer of nodules with rolled shell-fragments can be traced along 
the escarpment in a westerly direction as far as the great fall of rock just 
south of McCullough’s Bridge; and it may go farther, since the section 
is obscured by slips and a covering of soil. The occurrence of nodules 
associated with the rolled shells points to some concentration of the nodules 
