ISLE OF MAX. ALLUVIA. 



being conspicuous, while posterior waste may also have 

 obliterated the small traces of them which once existed. 



The substances which form the tract now under review, 

 consist of marie, clay, sand, and gravel ; neither of which 

 are so interesting, either m their positions or details, 

 as to require any very particular notice. The former is 

 successfully used in agriculture ; consisting of a mixture 

 of clay with calcareous earth, and in some cases with frag- 

 ments of limestone as well as of sand and mica, the ruins of 

 those primary rocks which furnished the argillaceous 

 ingredient. Shell marie does not appear to exist, and, in 

 every case, the calcareous ingredient seems to have arisen, 

 like the others, from the destruction of limestone rocks. 

 The position of this calcareous ingredient, particularly 

 where it occurs in fragments in the clay, is in some cases 

 remarkable, and equally with the transported granite, 

 points to a foreign origin. This is the case, among other 

 places, in the alluvia in the vicinity of Douglas, where 

 fragments of limestone are found imbedded in a position 

 superior to that of the calcareous beds which occupy a 

 tract on the southern side of the island. From this cause, 

 among others, the clay of the Isle of Man, forming the 

 basis of the soil which predominates in the cultivated 

 districts, derives its excellence, and for the same reason 

 it is generally rendered inapplicable to the purposes even 

 of the coarsest pottery ; the bricks formed from it crack- 

 ing in the fire, in consequence of the calcination of the 

 limestone. 



The larger boulder stones, which are dispersed over the 

 Isle of Man in various places, undoubtedly owe their 

 origin to the general cause already stated, which they 

 tend at the same time to confirm. Granite is the predo- 

 minant substance among these, the different blocks pre- 

 senting different varieties in composition. They are not 

 often of very large size, but are cut by the inhabitants for 

 millstones and for pillars, wherever they are of sufficient 



