186 CKUISE OF THE NEPTUNE 



allow the sedimentary deposits to preserve their original unal- 

 tered conditions. All the above rocks are grouped in the 

 Archaean, and further and closer examination will probably 

 show that it contains sill the members of the Laurentian and 

 Huronian found in the more southern Archaean regions of 

 Canada. 



Except in the northern part of Ellesmere, there is a consider- 

 able time-break in the geological sequence in the northeast 

 between the Archaean rocks and the Cambro-Silurian strata 

 which rest unconformably upon them. Schei found at Bache 

 peninsula, on the eastern side of Ellesmere, a series of stratified 

 sedimentary rocks resting upon the northern flank of the 

 Archaean and containing fossils of Cambrian age. These de- 

 posits have a thickness of nearly 1,500 feet, and are overlaid by 

 limestones containing Cambro-Silurian fossils. 



The Archaean rocks at the time of deposition of the lower 

 beds of the Cambro-Silurian limestones appear to have extended 

 southward from the vicinity of Bache peninsula in a gradually 

 widening ridge along the western side of Baffin bay and Davis 

 strait. In this manner they attained a width of seventy miles 

 on the southern side of North Devon, and occupied the entire 

 southern shore of Baffin island, being separated from the great 

 area of Labrador by the depression of Hudson strait, which 

 probably existed at that early period. Islands of Archaean rocks 

 may also have risen above the surface of the Cambro-Silurian 

 sea in the present island of North Somerset and on Melville 

 and Boothia peninsulas, as well as on other portions of the 

 northern coasts of the mainland, to the west of Hudson bay. 



The western Cambro-Silurian sea filled the present depres- 

 sion of Hudson bay, and extended far to the south and westward 

 of its present limits, outliers of limestone containing fossils of 

 this age, and very similar in mineral character, being found in 

 the valleys of the great lakes of Manitoba. From Manitoba 

 these rocks have been traced southward into the United States, 



