70 ROYAL SOCIETY OF CANADA 



what then ^vould apjjear in relation to them as a high plateau. Much 

 of the structure so defined suggests the features of lands carved by sub- 

 •aerial erosive agents and by them reduced to a peneplain. The charac- 

 ter of the terrace is perhaps best pronounced if a depth of about 500 

 feet be selected as a one time shore line, and the sea be supposed drawn 

 oil to that depth or what would have the same effect, that the side 

 of the continent had risen out of the water to that elevation above the 

 sea level of to-day. 



With a reconstructed shore at the depth named the physical features 

 that would then exist appear more suggestive than perhaps at any other 

 idepth, although it is far short of the limit of elevation to which much 

 evidence points as recently existing especially on the adjoining coast of 

 Newfoundland. 



Among the more marked features brought out by this assumed 

 elevation of 500 feet is : — a large inland sea or lake with an outlet 

 to the south. Then there are prominent extensions of existing pro- 

 montories and headlines, islands large and small, plateaux crowned by 

 knolls and bearing small lakes, a broad valley with a channel drained 

 at that depth, broad estuaries to the main drainage system and, perhaps, 

 some rocky peaks, river channels with sloping banks and islets, or with 

 sides precipitous in places. Besides these, and even perhaps of more 

 interest than all other features many deep isolated depressions often 

 close to knolls of elevation above the average of the neighbourhood. Im- 

 portance is attached to the seeming presence of these depressions and 

 one of the main conclusions submitted in this paper is based largely on 

 them. 



To ships approaching Halifax from the southward the soundings 

 supply but an imperfect guide to position, there is no gradual shelving 

 of the sea bottom as the shore is approached, but great irregularity may 

 be indicated by the lead. This condition though a source of anxiety 

 to the navigator is one of much interest to the investigator of the 

 'structure of the country in prehistoric times. It is evident that the 

 unevenness of the surface cannot be accounted for by ocean currents 

 in one place piling up banks and in another digging out the holes and 

 large depressions that exist, neither icould the inequalities be explained 

 by the action of icebergs, grounding, melting and depositing immense 

 loads of earth and rocks, which by the way are rarely indeed borne by 

 icebergs; nor is it possible to suppose that ocean currents could have 

 formed channels which are brought into prominence on the re- 

 construction map; channels which in places widen out into broad 

 valleys with gently sloping sides and elsewhere are narrowed with steep 

 if not precipitous walls. Some other agents than these must be sought 



