51 



For the greater part of the length of this valley the measures aie Cambrian 

 nearly or quite vertical and the succession of the Cambrian terranes i n 



is from side to side of the valley, i.e., from the northwest to the south-east brook valley- 

 side, and the whole series may be crossed in the distance of three- 

 quarters of a mile. But the series ia not complete, as the Bietonian 

 division is almost or quite removed by faulting and erosion from every 

 section in this valley which it has been possible to examine, and the 

 elisions on some sections cut out half the Johannian division as well. 



A few miles to the south-east of Indian brook basin, on the shore Peltura fauna 

 of East bay, there is a small outcrop of Bretonian shales and thin fossils. 

 flags, (surrounded by Lower Carboniferous shales with gypsum) that 

 carry a characteristic fauna. Here were found Sphcerophthalmus 

 Fletcheri, Parabolina Dawsoni, Pellura scarabeoides, Agnostus tri- 

 sectus, and other forms of the Peltura fauna. Nearer the head of 

 East bay, but inland from it on Gillis' brook, is the band of Bretonian 

 shales already described, containing limestone layers with Orthis 

 lenticularis, &c. 



Two basins of Bretonian slates have been recognized in the valley of wo basins of 



. .Bretontan 



the Mira river. One lies in the depression above Marion bridge where slates in valley 



the river widens out and takes on a lake-like appearance known as the 



' Grand Mira.' This basin lies between Johannian sediments on 



McLean brook and a low broad ridge of rocks of the same age that 



extends from Marion bridge some distance up along the right bank of 



the ' Grand Mira ' ; the basin extends in a north-easterly direction 



where it passes beneath an area of Millstone grit of the Carboniferous 



system. The other basin is a narrow one on McNeil brook, a stream 



discharging into the Mira river on the eastern side below Marion 



bridge. This basin is pinched out on McNeil brook a little below 



where the bridge of the Trout brook road is placed. It forms a 



narrow trough extending along McNeil brook to and beyond the 



bridge where the 'Big Ridge ' road (on the Geological map, the Cari- 



bou Marsh road), crosses. Beyond this point it has not been traced, 



but it may extend through a valley that runs along the north-western 



side of the Big Ridge and by McEchern's lake and brook connects 



with the ' Grand Mira.' It was from this basin on McNeil brook Fossilg of the 



that the fossils were obtained which first showed the existence of 



Cambrian rocks in Cape Breton. The fossils from this basin, found 



on McNeil brook, are Peltura scarabeoides, Spharophthalmus alatus 



and several Agnosti and Lingulellse. 



The area covered by Bretonian rocks in Cape Breton is insignificant 

 compared with that occupied by Johannian or Etcheminian sedi- 

 4J c. R. 



