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The N.Z. Journal of Science and Technology. [Sept. 
and thickness of adjacent seams, both point to the conditions of deposit 
being those of drift material rather than the coal being formed by growth 
in place. The relative small quantity of ash as compared to other brown 
coals in the country is somewhat strange, and points to the accumulation 
of drift material being formed on the shore of a land of comparatively low 
relief, and certainly of one which yielded very little waste to the estuaries 
which were formed on its coast-line. 
In addition to the coal the area contains valuable seams of fireclay, 
and there are as well numerous and thick beds of white quartz sand. 
I have not examined these with a view to determining their use for glass¬ 
making or other industrial purpose, but it is possible that these deposits, 
especially the fireclay, may eventually prove more valuable than the coal 
itself. 
( d .) Volcanic Rocks. 
The only igneous rocks discovered in the area are dolerite intrusives— 
(1) a large dyke in Iron Creek, and (2) sills in Broken River opposite 
the mouth of Winding Creek. These rocks are of the same general 
character as those of the Trelissick Basin, Sloven’s Creek, and the 
Esk River. 
The dyke is a dolerite of even-grained texture. The characteristic 
minerals are labradorite feldspar in laths, irregularly oriented ; augite in 
grains and aggregates, not distinctly pleochroic, moulded on the feldspar, 
but with little ophitic tendency ; olivine in clear crystals with little signs 
of decomposition as a rule, but in certain parts of the rock there are 
pseudomorphs of chalcedony, chlorite, and calcite, after some mineral which 
has the crystalline outlines of olivine, and may be derived from it; magnetite 
occurs freely in grains ; apatite in long and short stumpy needles. In this 
rock there is a considerable quantity of calcite, and also a clear, colourless, 
isotropic mineral with a lower index of refraction than balsam, occurring 
in patches of irregular shape and small size : these may be of glass, or they 
may perhaps be analcite. There is, however, no other feature of the rock 
which suggests that it is alkaline in character. 
The sills are finer in texture and are much more decomposed. They 
show a very large quantity of calcite, either in aggregates of crystalline 
grains or distributed through the mass of the rock. The augite is clouded 
with alteration products, and only occasionally unaltered remnants of 
crystals are visible, but the feldspar is fresh and shows little signs of decom¬ 
position. Ilmenite, in long needles and broken-comb forms, is also an 
important constituent. 
(e.) Relations to Neighbouring Areas. 
(See Fig. 1.) 
The Broken River coal area is only a remnant of a somewhat widely 
extended sheet which occupied the greater part of the Waimakariri inter- 
montane basin. The most considerable remnants are those in the Trelissick 
Basin and in the lower valley of the Esk River, but a small remnant lies 
near the old Craigieburn homestead south-west of Lake Pearson, on the 
West Coast Road (Hutton, 1887), and yet another occupies the lower 
part of Sloven’s Creek and the sides of Broken River near the junction. 
Although this last remnant is close to the area under consideration it 
is entirely cut off from it by a barrier of Maitai rocks, and it may be 
divided into several subordinate parts by similar dividing-ridges in the 
