40 THE CANADIAN NATURALIST. [Vol vil^ 



last-mentioned outcrop, limestone beds occur in cliffs skirting the 

 river margin. The uppermost beds of grey limestone, holding 

 intercalated crystals and silicified organic remains, belong to 

 the Corniferous formation ; whilst the underlying strata of bluish 

 limestone and fine-grained sandstone with irregular crystals of 

 calc-spar, denote the presence of the Water-lime group. We have 

 here exposed in one cliff two different formations belonging to 

 two totally different geological periods ; the uppermost or Corni- 

 ferous belonging to the Middle Devonian System, and the under- 

 lying one or Tentaculite limestone being of Silurian age. The 

 numerous intermediate formations, or those which in the seo- 

 logical scale intervene between the formations in question, were 

 being slowly deposited in other localities while the Tentaculite 

 limestone was for ages above the level of the ocean, or at least 

 formed the basin of a very shallow expanse of water, uninfluenced 

 by any currents whatever. Then immediately subsequent to the 

 deposition of all these formations preceding the Corniferous, the 

 long stationary Tentaculite limestone was gradually submerged 

 to a depth of several hundred feet, and on its unruffled surface 

 was deposited the Corniferous sediment, which subsequently was 

 upheaved above the ocean, remaining comparatively motionless 

 until about to be covered by the waters of the Glacial sea. 



South of the Maitland river, no exposures of rock have been 

 met with in Huron. Along the valley of the Bayfield we look 

 in vain for the appearance of the underlying rock, the river 

 through its whole course flowing over grey and blue clays of the 

 Quaternary age. But even here something of geological interest 

 awaits us. About three miles in a direct line from Lake Huron 

 and lying partially buried amid the clays along the river margin, 

 there is exposed what seems to be an outlier of a formation ap- 

 parently higher in the scale than the Corniferous. Its beds are 

 characterized by an extraordinary profusion of organic remains ; 

 the uppermost ones containing vast quantities of fragmentary 

 Crinoidal stems which mark in a special manner the presence of 

 certain strata of Uie Hamilton formation. Viewing it alike 

 from a lithological and a palasontological point of view, the infe- 

 rence would naturally be that we have here an outlier of the 

 Hamilton formation divided from the main area by denudation, 

 and manifestly proving the former extension of these higher de- 

 posits along the slopes of that synclinal, whose course from Lake 

 Huron to Erie is a somewhat unique feature in the physical 

 geology of Western Ontario. 



