172 LOWER SILURIAN OF CAPE BRETON — GILPIN. 



the bridge on Trout Brook Road gray, black and l)luish argillites 

 form clitls abounding in impressions of trilobites, including 

 Agnostus and an Olenus (or Sphoerophthalmus) allied to O. Alatus 

 of Boeck." The amateur who is willing to Avork up this district 

 Mall probably figure as the discoverer of many new and impor- 

 tant varieties of the life characterizing this interesting series of 

 strata. 



On the shore at Long Island there is a good section of these 

 measures exposed, but the beds are so disturbed by folding, 

 faults, &c., that no estimate of thickness can be given. The 

 following from Mr. Fletcher's measurements at this point will 

 serve to show the general character of the rocks met here. 



Sea green, and blue purple, whitish and gray, laminated, cal- 

 careous, hematitic felsites, micaceous slates and argillites, one 

 color passing into another, with thin beds of compact felsite and 

 quartzite. Red, coarse, calcareous sandstone, alternating with 

 greenish, laminated, micaceous, pitted marl, in contorted rolls, 

 from which the layers may be removed like the coats of an onion. 

 Greenish and blue papery slates, often contorted. White waving, 

 close grained quartzite and quartzose sandstone, sometimes fels- 

 pathic. Mottled fine grained, ferruginous sandstone, arenaceous 

 shale, and argillite, intersected by quartz and calcspar veins. 

 A very common rock is a compact and slatey grey or 

 bluish grey felsite, sometimes calcareous. In places the Pre- 

 Cambrian Syenite has lying directly on it a fine grained felsite 

 greenish, wnth glittering specks, and films of hematite. Many 

 of the argillites of this district are comparatively unaltered, and 

 are frequently mistaken for Carboniferous shales, so that explo- 

 rations have been carried on in them in the expectation of strik- 

 ing coal. Limestone is not abundant, but the beds are at many 

 points decidedly calcareous. At McLean's Point there are many 

 reticulating veins of calc spar in the rocks, which sometimes form 

 compact beds of limestone, having in places a cone in cone struc- 

 ture. 



At many points there are conglomerates frequently resting on 

 the Laurentian rocks. They are of various degrees of coarse- 

 ness, and consist of felsites, syenites, porphj'ries, gneisses, etc.. 



