158 Classes of Detritus, 



example, pebbles reposing in argillite, from ten to forty feet 

 in depth, form the bed of the Hudson from the head of tide 

 water at Troy, to near Albany. Seven miles below, sedi- 

 ment more or less fine is seen in the bottom of the river. 

 Dr. Hayden of Baltimore, has given numerous localities of 

 this kind, without any other object than that of giving us 

 simple matter of fact. 



Works of art are found in this formation, which distin- 

 guishes it from diluvion. It is a curious fact that no works 

 of art are found in the diluvion. It seems to prove, that 

 durable works of art were not common before the deluge ; 

 and that pasturage was the chief employment of the ante- 

 diluvians. 



VI. Analluvial Detritus. 



25. Stratified Analluvion. 



Whole rocks sometimes become soft detritus, without be- 

 ing removed from their original position. At Montezuma, 

 on the Erie canal, Comfort Tyler, Esq. dug a well, one hun- 

 dred and eighteen -feet deep. He perforated the diluvial 

 trough, then the lias and ferriferous stratum, and entered 

 several feet into the saliferous rock, where he found strong 

 salt water. These rocks were all in a state of disintegration, 

 and retained all their original contents, and all their charac- 

 ters excepting induration. I have traced this kind of forma- 

 tion southwardly to Cayuga lake, and up the lake to Spring 

 mills, a distance of about fifteen miles. This is in exact con- 

 formity with a general principle which seems to have been 

 overlooked. All rocks are found to be harder and to present 

 a more primitive aspect, as we approach their elevated and 

 bassetting edges. This character is well illustrated by the 

 lias, ferriferous and saliferous rocks just mentioned. Also by 

 the third graywacke of Lake Erie, in its approach to Catts- 

 kill Mountain ; and by the argillite and first graywacke as 

 they approach the primitive rocks of the Green Mountain 

 range. 



26. Superficial Analluvion. 



All rocks are subject to disintegration on their exposed sur- 

 faces. The common disintegrating agents, water and varia- 

 tion of temperature, are perpetually reducing the upper sur- 

 faces of rocks to the state of soils adapted to the production 

 of vegetables. As this detritus is not necessarily washed 

 from the place of its original production, it may be called 



