488 HOWOKTH ON SURFACE ELEVATION IN ARCTIC REGIONS. 



fresh-water seas. A subsidence of 400 feet would make Lake 

 Ontario discliarge its waters by the Mohawk and Hudson into the 

 Atlantic, convert Lake Champlain into a maritime strait, and form 

 islands of the States of New York, New England, and Maine, 

 New Brunswick and Nova Scotia; a subsidence of one-fourth 

 of this would carry the waters of the Missouri and the Upper- 

 Churchill and Mackenzie Rivers into Lake Winnij)eg, and convert 

 the plain country bordering the Rocky Mountains into an inland 

 sea. The raised beaches of Lake Superior are 100 feet above the 

 present level.* 



'' On Lake Superior, in Canada, deposits face the lake in the 

 *' shape of bare earth-banks and terraces. They are all the pro- 



" duce of the lake when standing at a higher level On 



'' Lake Huron are successive belts of water- worn erratics of large 

 *' size, one above another, with a few yards interval between each. 

 " On the summit of a cliff 100 feet high, Colonel Delafield informs 

 " me there is a range of water-worn stones, regularly strewn as 

 " on a beach, for 200 feet in length. These instances of remains 

 " of ancient deposits might be greatly multiplied, as they are 

 *' very usual in this lake when the vegetation permits them to 

 " be seen." I have extracted this passage from a very interest- 

 ing paper by Dr. Bigsby on Canadian Erratics,! which describes 

 similar traces as existing in nearly all the lakes of North America. 

 His resume of the evidence states that " the Canadas, in common 

 '* with all the western and northern parts of the United States, 

 " are mapped out by irregular concentric rings of terraces and 

 " ridges, sometimes hundreds of miles in circuit, which enclose 

 ^' the beds (with or without water) of lakes and ponds more or less 

 " closely. The mouths of rivers here and there break through 

 " these rings, and the rivers themselves are also bordered with 



" terraces The terraces are the margins of former 



*' bodies of water much loftier and larger than those now existing. 

 " These ancient lakes have been more or less emj)tied by the 

 " elevation of iheir beds, an elevation taking place perhaps very 

 " extensively, slowly, and variously" (p. 236). 



Having shown by the evidence of the lakes and rivers (those 

 gauges of level by which alone we can test the change of level 

 that is progressing in a country) that the interior of the northern 

 part of the American continent is rising as well as the coast, 

 we will now pass on to an examination of the remaining half 

 of the northern circumpolar regions comprised in Europe and 

 Asia. 



The remarkable changes that have taken place in Scan- 

 dinavia, in illustration of our subject, are among the elementary 

 facts of geology. They have given rise to an extensive litera- 

 ture, somewhat fierce in its controversial bitterness. The ques- 

 tion has been complicated by a difficulty which arises in many 



* Isblster'B " Geology of the Hudson's Bay Territory, &c.", " Quart. 

 Journal, Geological Society," vol. xi. p. 497. 

 t " Quart. Journal, Geological Society," vol. vii. pp. 215, &c. 



