206 THE PHENOMENA OF DRIFT, OR 



properly to belong to the glacial period of drift, than to the sunny 

 days of alluvium. Whether the deposit exhibited in PI. VIII, 

 Fig. 12, was formed before, or since, the commencement of the 

 historic period, I am unable to decide : but am inclined to place 

 it a little anterior to the latter. It occurs in a deposit of fine 

 gravel, sand, and loam, lying immediately above the clay, in the 

 south part of Northfield, in Massachusetts, on the stage road, near 

 Connecticut river. I give it chiefly as affording a fine example 

 of cross and inchned stratification in fine materials. It is only a 

 few rods in length. 



The occurrence of sand above the clay, in the formation under 

 consideration, is a fact to my mind very perplexing. I do not 

 see why it does not indicate a greater violence in the waters which 

 brought the deposits into the lakes and ponds, than when the clay 

 was in a course of deposition. Yet the occurrence of the sand 

 above the clay is no local fact, but is common all over the country 

 where the two deposits exist. Some general cause, therefore, 

 must be assigned for it. It is clear that rivers, in their present 

 state, bring down materials intermediate as to fineness between 

 the sand and the clay of the drift deposit. It is well known that 

 the mud produced by the grating of ice along the surface, is finer 

 than can be formed in almost any other way. Such mud ^vould 

 of course be the first to be brought into the ponds and lakes, if 

 the views advanced in this paper be correct. Afterwards the 

 materials brought thither must be coarser. I will not, how^ever, 

 enlarge on a subject which I feel unprepai*ed to discuss. 



Prof. Emmons has described a rather unique case, occurring 

 in New York, on the shores of lake Champlain. He finds there 

 a deposit of clay, resting upon smoothed and striated rocks, yet 

 beneath the principal deposit of drift ; and moreover containing a 

 few fossils of an arctic character. It would seem as if these shells 

 continued to exist for some time after the commencement of the 

 drift period, when nearly all organic life appears to have ceased ; 

 and that a reduction of the energy of glacio-aqueous agency 

 allowed the formation of this deposit in that locality : after which 

 its force again increased and covered the surface with detritus. 



