Portland and its Vicinity. 



341 



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wards the river, but in the opposite direction ; so that the 

 trees all lean more or less from the river. The ridges 

 on which they stand, are elevated but a few feet above 

 the general level, which, is from fifteen to twenty feet 

 below the original level of the plain. Between these 

 ridgeSj the surface is composed of a very light bluish clay. 

 And this stratum, occurring perhaps twenty feet below 

 the surface, and being exceedingly plastic, appears to 

 have been the principal occasion of so extensive a slide. 

 The upper layers of clay are of a darker color ; exactly 

 resembling the clay beds that are scattered over New 

 England so abundantly. Above the clay, are a few feet 

 of hght sandy soil, which constitutes the surface. ^ 



It is a curious fact, that these slides took place, as I 

 was informed by Mr. Edwards, of Portland, in time of a 

 drought, in summer. Perhaps the unusual exsiccation 

 caused the upper strata to crack more readily, w^hile the 

 stratum of whitish clay, being so deep in the earth, still 

 retained moisture enough to be very plastic. It Is diffi- 

 cult, bow^ev^er, to conceive how the shde should have 

 been so extensive, without any unusual convulsion. It 

 certainly resembles those land slips that have resulted 

 from earthquakes; but I have not learnt that such an 



V 



event was concerned in its production. 



I hope the annexed birds-eye sketch may enable the 

 Society to form a more accurate idea of this land slip, 

 than my ^description will convey ; although it was taken 

 in great haste and by the eye alone. And all the dimen- 

 sions of this slide, that have been mentioned, are only 

 approximative estimates, obtained in the same manner. 

 But the case is too interesting to be passed without 

 notice. - . ' 



