ARCTIC ISLANDS 117 



The country, formed of the limestones and other Palaeozoic 

 rocks, differs in its physical character from that already des- 

 cribed. On the northern islands, where these rocks attain a 

 considerable thickness, the land rises in abrupt cliffs directly 

 from the sea. The summits of these cliffs vary in elevation 

 from 1,000 to 3,000 feet, while the country behind is a table- 

 land rising in steps inland, the front of each step being a cliff 

 usually of much less thickness than the initial one by which the 

 land rises from the sea. In the more northern islands the higher 

 portions of these tablelands support ice-caps generally much 

 thinner than those covering the adjoining Archaean tablelands. 

 The coasts composed of these flat-bedded limestones are deeply 

 indented by narrow bays or fiords in the valleys of the more im- 

 portant streams ; each small stream and rill flowing off the land 

 has left its sculptured mark upon the cliffs, so that the whole 

 resembles, on a great scale, the banks of a stream cut into a 

 deep deposit of clay. This minute sculpturing of the rocks 

 points to their ^having been elevated above the sea for a very 

 long period, during which time the streams were actively at 

 work cutting their valleys down to the sea-level. 



These high abrupt cliffs are characteristic of the islands 

 on both sides of Lancaster sound and to the northward 

 of it. 



The limestone islands of Hudson bay and that portion of 

 southwest Baffin underlain by these rocks are very low and 

 flat, with shallow water extending several miles from their 

 shores. 



Those northern islands, wholly or in part formed of the 

 Mesozoic rocks, are characterized by low shores and no great 

 elevation inland. At Ponds inlet, where an area of Tertiary 

 deposits occurs, the country overlying it forms a wide plain 

 deeply cut into by the streams that drain it. 



