340 



THE CANADIAN NATURALIST. 



[Vol. ix. 



bere: age. This absence of the Niao;nra limestone is 2:eneral in 

 Nova Scotia, and along the Atlantic margin of North America. 

 Farther West, in Northern New Brunswick, and in Gaspe, mas- 

 sive limestones appear, but they attain their greatest development 

 in the interior plateau south of the great lakes. 



With reference to the dates and disturbances of these deposits, 

 it may be affirmed that there was much volcanic action at the 

 time of the deposition of the Cobequid series; that this series 

 experienced no little disturbance and alteration before the Upper 

 Silurian rocks were laid down ; that the latter were subsequently 

 much folded and fractured before the Carboniferous Period,, 

 and that since that period there has been sufficient movement 

 to cause the carboniferous rocks to be locally highly inclined 

 and faulted. In the trappean beds, interstratified with the 

 Lower Carboniferous conglomerates of the coast to the eastward, 

 there is evidence of the continuance of igneous action up to that 

 time. As to the age of the iron deposits, the formation of the 

 great veins of specular iron and ankerite was probably contem- 

 poraneous with the earliest disturbances of the Cobequid series, 

 and previous to the Lower Helderberg age. The great inter- 

 stratified beds of Hematite are undoubtedly of the latter age, 

 unless the lowest bed should be regarded as between this and the 

 Clinton. The veins of Limonite, mixed with oxide of manganese, 

 are later than the Lower Carboniferous, and constitute here as in 

 the Cobequids a secondary product of the decomposition of the 

 carbonate of iron contained in the ankerite and spathic iron of 

 the Cobequid series. 



IRON ORE BED. WEBSTER LOCATION. 



a. drift. b. slaty rock. c. iron ore. 



