PEOMONTOET MOUNTAINS. 423 



while the limestones farther south afforded: 



Zajphreniis Stanslmryi. 

 Productus semireticulatus. 



These fossils are all clearly of Carboniferous age, though of themselves 

 not distinctly characteristic, either of the Upper or Lower Coal-Measure 

 limestones. The thickness of the series, and its relation to the underlying 

 Archseans, however, as well as its general lithological character, all serve 

 to ally it rather to the latter division. 



About 14 miles south of Benada Peak, the Carboniferous limestones are 

 found to abut unconformably upon a series of Archaean schists, which occupy 

 the whole lower 7 or 8 miles of the range, with a strike north 30° to 35° west, 

 and a dip to the northeast. The Archaean strata consist largely of siliceous 

 schists and imperfectly-bedded hornblendic and micaceous gneisses, together 

 with thick beds of quartzite and more or less interspersed argillaceous schists. 

 Just west of the southernmost extremity of the range, the Archaean rocks 

 come nearly down to the water's edge, presenting a cliff, some 50 feet in 

 height, of dark argillaceous schist, which has apparently a dip of 25° to the 

 west. Along the cracks and fissures, this rock appears to decompose readily, 

 and is found to be coated with an efflorescent substance, which, when applied 

 to the* tongue, gives the characteristic astringent taste of alum. The fol- 

 lowing analysis of this salt was made by Mr. R. W. Woodward: 



Alumina 1 1.26 



Ferric oxide 0.35 



Magnesia 19.02 



Soda 2.24 



Potassa ■- 0.28 



Sulphuric acid : 64.96 



Chlorine 1.85 



Oxygen 0.04 



100.00 

 The analysis of this alum gives no water of crystallization. 



