45 S Geology of 



formed by the junction of the Cox range with Mount Somers, a series 

 of seams of lignite occurs having an average dip of 14 deg. towards 

 X.X.'W.. and reposing on quartziferous porphyry. This series begins 

 with beds of porphyry tufa, and fire-clays, covered by a succession of 

 shales, alternating with seams of coal, two to five feet thick — the coal 

 consisting of distinct layers of earthy brown coal and lignite, the 

 latter exhibiting quite clearly the woody structure. Another series of" 

 coal seams, situated on a spur on the Cox hill ranges, about five to 

 six hundred feet above the foot of these hills where they rise from the 

 Canterbury plains, seem to skirt the ranges. They consist of deposits 

 similar in character to those previously described, also reposing on 

 porphyry tufa. There is first a lower seam of 2 feet 6 inches,, 

 separated from an upper seam 2 feet 4 inches by 4 inches of shale 

 covered by fire-clay. These strata dip 35 deg. to the N."W. by W., 

 and consequently appear to dip below the quartziferous porphyries of 

 which the ranges consist. However, it is apparent, from the ridges 

 rising in front of the series, that a small lagoon was at one time here 

 formed by the sea, and filled up in couse of time by the above- 

 described beds. 



Another basin, already of practical value, is situated in the 

 neighbourhood of the junction of the River Stour with the Ashburton. 

 It occurs in a depression amongst the quartziferous porphyries, 

 which, before the main river had cut through their eastern boundary, 

 formed here, doubtless, a ridge of considerable dimensions, behind 

 which the sedimentary beds of lacustrine or littoral origin could be 

 accumulated. This basin, somewhat triangular in shape, is about two 

 miles in breadth and length. It appears that the porphyries had already 

 undergone considerable denudation before the newer beds were formed, 

 they having been deposited on the sides of steep escarpments and cliffs. 

 The lowest beds consist of porphyry tufas, lying generally at a high 

 angle, and following the outlines of the spurs. They are of great 

 variety in colour and texture, often with a fine ribboned appearance, 

 white and yellowish colours being predominant. They are well exposed 

 in Coal Creek; gradually they become darker, and are succeeded in 

 that locality, by shales upon which a seam of brown coal of good quality 

 reposes, 14 feet in thickness, of which however only the lower portion 

 of S feet was extracted, when I visited the locality in 1S71. Since 

 then another method has been adopted, the coal seam being stripped and 

 its whole thickness worked. This coal has a dip of S deg. towards the 

 4SL-& E. 



