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ing, upon the slide or fall of land upon the Presumpscot River, 

 near Portland, Maine, some years since, in which discussion 

 he had i)articipated, read documents from parties who visited the 

 locality immediately after the event occurred, in order to show 

 that the views maintained by him were correct, viz : that the 

 phenomenon was due primarily to a partial washing out of the 

 substrata by the action of the river ; — that it might be more 

 truly described as a fall or sinking of the surface, attended with 

 some sliding towards the river, which it croAvded from its course, 

 rather than to a sliding action alone of the surface, occasioning 

 a denudation of the substratum of dny. The presence of this 

 clay to such an extent on the surface, he described as resulting 

 from its being forced up by the crushing weight of the soil over 

 it, through the fissures and divisions that occurred above when 

 the fall took place. This spread over the disturbed area to a 

 considerable extent, and formed numerous hillocks, Mr. Bouve 

 then exhibited a fine series of conci'etions from the clay, most of 

 which had a nucleus of some organic body. Among these nuclei 

 were coprolites of fishes, fish-bones, joints of crabs, Balani, shells 

 of the genera Mya, Bulla, Nucula, and Saxicava. These con- 

 cretions, and those from other deposits of clay, are not, as has 

 been supposed by some, mere balls or masses of clay which have 

 become indurated by carbonate of lime imparted from the nucleus, 

 but true segregations of carbonate of lime from the solution of 

 this substance disseminated in the plastic clay. These bodies 

 ordinarily contain about 50 per cent, of carbonate of lime. They 

 do not always have a nucleus ; on the contrary, those from many 

 localities very seldom have any. These seem by no means neces- 

 sary for their production. Undoubtedly the carbonate of lime in 

 the plastic clay, acted upon by elective affinity, was led to draw 

 itself towards certain points, and to arrange itself more or less 

 concentrically about a centre where might be or not a nucleus of 

 some foreign body. Why the carbonate of lime did not in such 

 cases crystallize, is more than is clearly understood. Probably, 

 it might have something to do with the mechanical action of the 

 clay as a disturbing element. 



In cases where the forms are flattened disks, or lenticular, as 

 in some deposits, it may be supposed that the strata of clay were 

 of diffex'ent density. This would account for the flattening, inas- 



