10 



older rock wliich have afforded no fossils, and which probably 

 underlie those just referred to and may be Lower Silurian beds 

 tending downward to the Cobequid series and connected with it. 



Rocks of this character are well developed in the basin of 

 Lake Murdoch, where, according to Mr. Gilpin, they are cut oft" 

 from the Blanchard ore-series by a fault on the southern side. 

 They are traceable to the eastward, .ipparently underlying the 

 beds associated with the " Webster" ore-bed, and are well seen 

 still further to the eastward on the upper waters of the French 

 River. The.se Is differ considerably in mineral character from 

 any others in the district, though resembling in this respect rocks 

 seen at the Blue Mountain, near Eden Lake, an'^ on the East 

 Branch of the 8t. Mary's River. They contain tliick beds ol" 

 Nacreous or Ilydro-mica slates, coarse slates, sometimes haviui; 

 :i conglomerated or brecciated appearance, green chloritie or 

 epidotic rocks, quartzite and agglomerate, and felsitic rocks. 

 They '.ave afforded no fossils, and appear to me to be quite dis- 

 tinct from the Upper Silurian formation. In the meantime they 

 may be connected witli the Cobequid series, with the typical 

 rocks of which stries tliey are certainly closely associated t'artlier 

 to the eastward. 



One of the marked i'eatures of the Upper Silurian in the dis- 

 trict in ijuestion is the great development of bedded red hematite, 

 and of rocks more or less impngnated with this ore. Witli re 

 ferenee to its origin, this ore is evidently a marine deposit, and 

 formed under conoitions sufficiently favorable to marine life to 

 enable it to contain many shells of Brachiopods and remains oC 

 other animals. It is evidently a chemical deposit or precipitate, 

 and often assumes an oolitic structure. In the coarser or mor'> 

 impure bed« the little concretions of oxide of iron often surround 

 grains of sand, and the ore passes into a ferruginous sandstone. 

 The following section taken from a MS. Report of Dr. G. M. 

 Dawson shows the great development of the lower bed in one of 

 its exposures. These deposits (A' iron ore apparently began locally 

 in an early jiart of the Upper Silurian period, and were continued 

 into the Lower Helderberg period, while in the western part of 

 Nova Scotia, in the Nictaux district, we have evidence of their 

 continuance into the Oriskany age. 



Another marked feature of these deposits is the absence of any 

 representative of the great Niagara limestone, and the consequent 

 passage upward of (Miutoii deposits into tho-e of Lower Helder- 



t ' 



