196 Fossiliferous Rocks in Nova Scotia. 



more in detail, and of submitting full collections of their fossils to 

 the proper authorities, in order that their true age and the cha- 

 racter of their organisms may be determined. 



I would refer also to a subsection, which althouofh not so 

 interesting to the collector may be of equal interest to the geolo- 

 gist, as it is possibly to be regarded as a descending continuation 

 of the Airsaig section. It occurs at Doctor's Brook about 24- 

 miles east of Arisaig Pier. This will make the whole Arisaig 

 section extend about 5 or 6 miles S.E. and N.W. 



The Silurian strata are here very much altered and distorted, 

 arising, as Dr. Dawson has already observed, from volcanic action 

 of the carboniferous era. Of this there are obvious remains exist- 

 ing at various points along the sea shore from the conglomerate 

 on the east to the conglomerate on the west of the Arisaig Silu- 

 rian strata, or from Malignant Brook till beyond McCara's Brook, 

 a distance of at least ten miles. In Malignant Brook and a little 

 brook to the eastward, we find subcrystalline trap in immediate 

 contact with the lower carboniferous conglomerate, and the latter 

 has consequently become very much hardened ; to the west of 

 this the section is obscure and depressed till wc reach a small 

 brook having elevated ground on its western side, and there is no 

 appearance of rock of any kind until we meet the subcrystalline 

 trap and altered Silurian strata of Doctor's Brook. From this 

 point to Arisaig Pier we find the same kind of trap in contact 

 with the Silurian strata, and converting these into a red jaspida- 

 ceous rock or otherwise hardening and altering them in proportion 

 to their proximity to the point of contact. The results are the 

 conspicuous red and oblong rock locally known as the " French- 

 man's Barn," the breakwater of Arisaig pier, the hardening and 

 tilting of the slate and shale near the Frenchman's Barn and 

 the prevailing disorder of the Arisaig Section. 



When we again meet with volcanic rock, it assumes the form 

 of beds of amygdaloid associated with the lower carboniferous 

 conglomerate at McCara's Brook.* This rock has suffered much 

 from denudation as is evident from the horizontal section on the 

 beach; a large mass has been dislodged by the frosts of last win- 

 ter and it is evident that after a number of years it will entirely 



* For a detailed notice of this place see Journal of Geological Society 

 Vol. 1. p. 239. 



