JYotice of Hayden's Geological Essays. 49 



soii=ietliing like correct ideas of the causes and operations, 

 by which they were produced ; and possibly too of the 

 times at which they took place. 



Among the most prominent of these changes (and which 

 may be considered, as being one of the most interesting fea- 

 tures in the geology of this country) is the alluvial region, 

 skirting the Atlantic ocean. 



It is this which constitutes the principal subject of the 

 present work, and in the examination of which, he has en- 

 deavoured to adduce facts sufficiently numerous and strong, 

 to prove that the whole region, with the attendant phenom- 

 ena, is the result of the operation of currents, that flowed 

 from the north-east to the south-west ; or from the north to 

 the south over the whole continent of America." 



The existence of the vast alluvial district of the southern 

 American states, has ever appeared to us,as it does to Mr. Hay- 

 den, as a very interesting geological fact, and by no means, 

 to be accounted for by the commonly received opinions re- 

 specting alluvion. In Mr. Hayden's view, there is no cir- 

 cumstance that affords so strong an evidence of the cause 

 of its formation, as that of its having been deposited by a 

 general current, which, at some unknown period, flowed 

 impetuously across the whole continent of America; and 

 that from north east to south west." 



Those who may regard this opinion with the smallest de- 

 gree of favour, will be struck with the numerous prooft 

 which the author has adduced in its support. 



The almost universal existence of rolled pebbles, and 

 boulders of rock, not only on the margin of the oceans, 

 seas, lakes, and rivers ; but their existence, often in enor- 

 mous quantities, in situations quite removed from large wa- 

 ters ; inland, — in high banks, imbedded in strata, or scatter- 

 ed, occasionally, in profusion, on the face of almost every 

 region, and sometimes on the tops and dechvities of moun- 

 tains, as well as in the vallies between them ; their entire 

 difference, in many cases, from the rocks in the country 

 where they lie — rounded masses and pebbles of primitive 

 rocks being deposited in secondary and alluvial regions, and 

 vice versa; these and a multitude of similar facts have 

 ever struck us as being among the most interesting of ge- 

 ological occurrences, and as being very inadequately ac- 

 counted for by existing theories. Pebbles may, in given 



Vol. Ill No. 1. 7 



