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GEOLOGY OF THE FIRST DISTRICT. 
would be sufficient to cause the detachment of vast quantities of ice in the polar regions, and 
its transport towards the equator by the polar currents ; and the acceleration of currents from 
such causes are capable of an approximative calculation. 
Summary of Conclusions on the Drift, 
On reviewing all the facts on the phenomena of the drift, I am led to infer, 
1. That the transport of drift, and the production of scratched and smoothed surfaces, the 
belts of boulders, and the gravel and boulder hills, or diluvial elevations and depressions, 
were contemporaneous. 
2. That the drift was transported by the aid of currents, bui not by them exclusively; 
since enormous blocks could not have been transported by them alone without removing beds 
of gravel, sand and clay, on which many of them rest. Neither could the theory of glaciers 
account for them in level countries, nor for the scratches hundreds of miles from any elevated 
lands, on strata that show no signs of disturbance since their formation, as is the case in Ohio 
and the Western States, and in the western part of New-York. 
3. That ice, aided by currents, has been the cause of the transport of most of the drift, 
which has been dropped where we find it (in consequence of the thawing of the ice); diffused 
in scattered blocks, boulders and pebbles ; collected in belts, like an ancient shore ; in groups, 
where a raft of it had grounded ; in gravel hills and valleys, with boulders and blocks, where 
ice islands had grounded and dropped their burthen around them, or where eddy currents had 
kept them floating over limited areas, as we see in many valleys, and on Long island, the east 
and southeast parts of Massachusetts, and various other parts of the country. 
4. That the same causes continued to act after the drift epoch, during the quaternary 
period, but modified in force, in consequence of a partial emergence of the land from the 
ocean, obstructing the free flow of water over the higher lands, and confining it within certain 
limits in the present great valleys of drainage in North America. 
5. That the periods of the drift and quaternary deposits were separated by this partial 
emergence of the land, altering the relative levels of the sea and land. 
6. That the causes of the transport of the drift, and all the phenomena of that period, may 
be referred to the temperature of the earth, and the dynamical laws regulating its motions. 
7. That the periods of the drift, and of the upper drift, were periods when the currents 
were stronger than at the intermediate and the present times, caused by collapse of the crust 
of the globe upon its nucleus by refrigeration, causing an acceleration of the velocity of ro¬ 
tation ; and this, a consequent disturbance of the form of equilibrium of the spheroid of rota¬ 
tion, which would be compensated by the flow from the polar regions, and an accelerated flow 
of the equatorial currents. 
8. That there was a temporary change of climate at those periods. 
