Xxii TABLE OF CONTENTS. 
Page. 
May therefore reason from them in times past. 222 
Discussion of the problem of the drift confined to North-America. 222 
Three propositions must, from facts and observations adduced, be admitted.... 223 
Drift deposits ascribed to the action of the polar and equatorial currents.223 
Discussion of this question. 223 
Influences of these currents in the distribution of drift.223 
Northern current from Hudson’s bay and polar seas... 323 
Gulf stream up Mississippi valley. 223 
Great drift deposits consequent on their meeting. 223 
Southward transport of fine materials by northern current.223 
Eastwardly tendency of southward current into the valley of the great 
lakes, and dynamical law causing it..... 223 
Cause of the rarity of erratics south of the Ohio and Missouri, and of the 
elevated country of Pennsylvania, southern New-York, &c. 223 
Scratches evidently due to floating ice containing rocks grinding on the 
bottom, from review of facts. 223 
Glacier theory inapplicable, and why. .. 224 
Directions of scratches of Ohio and West referred to the resultant of the 
directions of the polar and equatorial currents .. 224 
Direction of scratches of western New-York explained.224 
Of Mohawk valley explained. 224 
Of transverse valleys to the south in New-York explained.224 
Of eastern line New-York, and in Massachusetts and Connecticut, 
explained. 224 
Of Hudson valley. Great valley, and transverse valleys explained.. 225 
Of New-York island.... 225 
Regions not materially affected by the phenomena of drift. 225 
Eastwardly branch of the gulf stream... 225 
Its influence on the drift of New-Y ork and New-England. 225 
“ Diluvial elevations and depressions ”. 226 
Explanation grounded on similar effects of icebergs... 226 
Strong objection. Rocks and pebbles not all from far north. 226 
Icebergs formed on our own coast as they are supposed to be formed at the 
north, insufficient to explain . 226 
Effects of ground ice, sufficient, with shore ice and glaciers on coast.226 
Facts connected with ground ice. 226 
Temporary change of climate indicated. 227 
Causes of, from physical considerations. 227 
Summary of conclusions on the drift deposits... 228 
