136 ROYAL SOCIETY OF CANADA 
Note.—Besides the above characteristic geological formations occur- 
ring in the Ottawa district, may be mentioned a number of intrusive 
masses and dykes which appear on both sides of the Ottawa river within 
the radius of twenty miles. The manner in which these appear to affect 
and alter the rock masses with which they come into contact seem to 
indicate their comparatively recent origin. Some of these may possibly 
belong to that group of eruptives to which the rocks of Mount Royal, 
Rougemont, Belceil and other masses belong. 
THE Post-TERTIARY OR QUATERNARY SYSTEM. 
To this system are referred the unstratified boulder clays or till and 
numerous phenomena of glacial deposits so extensively developed in the 
Ottawa Valley, which along with the marine clays and sands as well as 
fresh-water and estuarine deposits constitute the earth or soil of the 
district. 
The boulder clay or Labrador formation.—No special formationai 
name or designation has as yet been ascribed to the series of boulder 
clays which vary in thickness from a few inches or feet to upwards of 
one hundred feet in thickness, and which overlie the subjacent glaciated 
and striated surface of the ancient paleozoic rock formations in the 
Ottawa district. 
No special designation either has been given as a formational name 
to that extensive deposit or sheet of boulder clay or till formed by the 
“Labradorean Glacier” which was so generally spread over the provinces 
of Quebec and Ontario and the country to the south during the glacial 
period. ‘The term Labrador formation does not appear inappro- 
priate to designate such deposits as have been described as “ glacial,” 
“till,” or “boulder clay formation.” This formation is met with 
throughout the Ottawa district and the materials which compose it con- 
sist of accumulations of the more or less travelled, broken, ice-scored, and 
rolled fragments of all the rock formations which the great Labradorean 
glacier and all its lateral ramifications met along its way, and deposited 
in its different stages until the close of the glacial period, when the 
Champlain period of submergence began. It was at this time that this 
same Labrador formation was modified and considerably denuded, 
carried away and re-deposited, forming the Leda clay and Saxicava sands 
overlying. 
These boulder clays as is well known were deposited for the most 
part at the time when land ice prevailed in and about Ottawa; when 
great accumulations of snow and ice in the form of glaciers had gathered 
Ly 

