898 Transactions. — Geology. 



gorge itself the limestone dips 25° S.S.E. Immediately to the 

 north, on the right hank of the river, white sands with rounded 

 calcareous concretions occur, dipping 60° N.W. ; while a little 

 further up the river the limestone, apparently horizontal, is 

 underlain directly hy green sandstone with ferruginous concre- 

 tions. Probably the white sands have slipped from above the 

 green sandstone, as they occur in that position more to the 

 west ; but the locality requires further examination. Further 

 up the river the green sandstone with concretions dips 25° 

 W.N.W. 



In Waterfall Creek, which flows into Broken Kiver fi'om the 

 west, there is a very fine section. A fault goes up the bed of 

 this creek having a downthrow to the north, and in consequence 

 the left bank is formed of grey marl, and the right bank of green 

 sandstone with ferruginous concretions. The exposure of the 

 green sandstone here is about 300 feet in thickness, and on it 

 rests white sandstone with concretions, about 100 feet, followed 

 by another 100 feet of marl. This is followed by the lime- 

 stone, which is here not less than 300 feet in thickness. The 

 stream runs through a narrow gorge in the limestone, forming 

 two waterfalls, and the dip is 40° W.S.W. The limestone covers 

 a considerable amount of surface between here and the Hog's 

 Back, forming a syncline (PI. XXV., Section II.), with the axis 

 lymg about N. by E. and S. by W. At the north end of the Hog's 

 Back the dip is 55° E., but more to the south the dip gets greater, 

 until in Hog's Back Creek, at the southern end of the hill, it is 

 nearly vertical. In Trout Creek, a small stream lying a little 

 north of Hog's Back Creek, the eastern arm of the syncline is also 

 highly inclined, the dip being 80° W.N.W. ; so that this syncline 

 is narrowed and steep at its southern end, while it broadens and 

 flattens to the north. 



Craigiebnrn Outlier. — This patch of the lower beds of the 

 Waipara System lies outside the Trelissick Basin, fi'om which 

 it is separated by a low ridge of pala?ozoic rocks called the 

 Craigieburn Saddle. It belongs to the valley in which Lake 

 Pearson lies, and is 300 or 400 feet below the Craigieburn 

 Saddle. On the left bank of the stream two seams of 

 good brown coal are exposed. The upper of these seams is 

 7^ feet or more in thickness ; the lower shows 8 feet of coal, 

 but the bottom has not been laid bare. These coal seams are 

 separated by a bed of brown clay 5 feet thick. The coal scams 

 are overlain by pale soft sandstone with streaks of coaly matter, 

 and this by a ferruginous conglomerate containing rounded 

 pebbles of palreozoic sandstones and quartz mixed with pebbles 

 of liparite, like those of the southern side of the Malvern Hills 

 and the Rakaia Gorge. The dip of the coal beds is 25° N.W., 

 and the whole series is overlain uuconformably by horizontal 

 beds of silt, which were probably deposited during the last great 



