253 



The species most abundant is jjrobably the Leperditia Canadensis, var 

 Louckiana (Jones.) 



The associated bed of limestone exhibiting numerous and large 

 concentric patches of rot;k supposed to rei)esent the Stromcitocerium 

 rugosum of Hall, is exposed along the road a considerable distance, and 

 fine specimens have been collected of what appears to be the above 

 species. A doubt still exists in the mind of the writer as to whether 

 or not this bed, which is almost if not entirely composed of this 

 organism, may not be merely the result of concretionary action. Micro- 

 scopic sections of specimens prepared by Mr. Weston have not given 

 any characteristic st>'uctui-e. Besides the above there were collected : 

 Columnar ia i7iceria (Billings), a fossil coi'al ; a P lenrotoniaria like P. 

 pauper (Bill.), an Orthoceras sp. and Leperditice already refu'red to. 

 There is but little donbt that the strip of country lying between this 

 place and Ottawa, now occupied by the Ottawa River, and extending 

 some distance on either bank, presented at one time a perfectly flat 

 and continuous aspect. 



Denuding agenfies have evidently been at work in forming the 

 bed of the Ottawa River and also to a certain extent Lake Des Chines 

 — agencies " which during the " glacial epoch " must have been much 

 more active than the present slow but sure denuding action of subaerial 

 or atmospheric erosion. 



Another very typical exposure of the Chazy formation was 

 observed and examined to the eastward of the Rideau Hall grounds 

 close to where the measures of the Trenton formation characterized l)y 

 the abundance of fossils peculiar to that horizon, and considerably dis- 

 tuibed owing to a local fault, come in contact with it. 



The characteristic bed of concretionary (?) or laminated limestona 

 is well exposed over a considerable aiea in the country lying between 

 Mr. Matheson's property and the Rideau Hall grounds, occupying the 

 superior portion of the measures throughout the greater part. This 

 area, as at present known, presents an irregular contour bounded on 

 almost every side by faults and dislocations of purely local oiigin, 

 bringing the measures of the Chazy in contact with those of the Black 

 River, Trenton, and Utica (?) formations — showing how intricate and; 

 at the same time interesting the geology of Ottawa is. 



