338 J. D. IVES 



possible to ascertain wiiether or not the entire coastal zone was submerged 

 by ice at one and the same time. An extension of this discussion can be found 

 in the Hterature and it cannot be pursued any further in the present instance. 

 An additional problem, probably largely confined to the High Arctic, is that 

 certain types of inert ice cover could have existed in the past, no trace of which 

 remains today. This is especially important in the areas designated as High 

 Arctic refugia in the Queen Elizabeth Islands. 



It is upon this basis of fundamental disagreement in interpretation of the 

 available evidence, however, that a review will now be made of the physical 

 conditions of the eastern Canadian seaboard. The available, and frequently 

 conflicting, evidence from this region will then be presented and its significance 

 discussed. 



PHYSICAL CONDITIONS OF THE EASTERN CANADIAN SEABOARD 



From Cape Breton Island the eastern Canadian seaboard stretches generally 

 northwards for approximately 4500 km (Fig. 1). It may be divided into four 

 great sectors: the Maritime-Newfoundland sector which has predominantly 

 low coastal areas, excepting Long Range and the Shickshock Mountains; 

 Labrador, with moderate to low coasts in the southern half and mountainous 

 fjord coasts north of Nain; Baffin Island, with a fjord and high mountain 

 coast along its entire 1600 km length; here coastal summits exceed 1500 m 

 altitude and at least two groups of high rocky islands lie up to 30 miles off" the 

 coast; and finally the Devon-Ellesmere sector which extends for more than 

 1000 km in a general north-south direction and is somewhat similar in 

 character to the Baffin Island sector. 



One very important consideration is that the present climate of the eastern 

 seaboard ranges from moist temperate in the south to High Arctic desert 

 in the north, and this great range of climate presumably existed throughout 

 the Pleistocene period. One reflection of this chmatic range is that present-day 

 glacierization increases in extent northwards from the Kaumajet Mountains 

 so that from Pond Inlet to northern Ellesmere Island more than 70 per cent 

 of the coastal zone is ice-covered. Another important consideration is the 

 extent of the continental shelf: little can be said of the area north of Hudson 

 Strait, but southwards the shelf is moderately to extremely broad ranging 

 from 100 to 400 km. FinaUy, the character of the bedrock geology is vital, 

 although in this respect also little systematic data is available. With a few 

 small areas excepted, the coastal zone from the Gulf of St. Lawrence to north- 

 ern Ellesmere Island is composed of Archaean rocks, principally a suite of 

 acidic granitic gneisses, much of which are probably meta-sediments. Abrupt 

 local variations occur within the gneissic group yet there is a general lack of 

 distinctive rock types. Furthermore, distinctive rock types do not generally 

 occur within several hundred kilometers of the east coast. Thus great difficul- 

 ties arise when DahTs (1961) criteria for the confirmation of true glacial 



