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Secondary mountains are, generally, marked by a softer outline ; 

 and frequently possess the distinctive character, of being composed 

 of, or at least, of containing within them, the fossil remains of 

 organized substances. They always rest on, and sometimes cover 

 primary mountains ; and very commonly, also, they lean on their 

 sides, or invest them. The secondary mountains are formed, like 

 the primitive ; of either one species of stone, or of strata of different 

 species. Some are said to be derivative, being supposed to have 

 originated from the disintegration of primitive mountains. 



The substances, of which the secondary mountains are chiefly 

 composed, are lime-stone, swine-stone, marlite, chalk, and gypsum. 

 They are also, sometimes, formed of indurated clay and lithomarga, 

 jasper, porphyry, trap, silicious sand-stone, and other substances, 

 which belong also to the primitive mountains. 



The various strata of which the earth is composed, as deep as the 

 curiosity, and the necessities of man, have induced him to explore 

 them, manifest, in a most striking manner, the wisdom displayed in 

 the arrangement of the materials which compose the present world. 

 The first layer, generally consisting of a rich black mould, is formed 

 almost entirely of the remains of innumerable animals and vegeta- 

 bles, which, having lived through their destined periods, have been 

 resolved into their first principles. This substance, laying at the 

 surface, where alone it would be of utility, yields sustenance to the 

 vegetable kingdom ; and thereby becomes the support of man, and 

 of the rest of the animal creation. Beneath this, is most com- 

 monly found, a thick bed of clay, which furnishes the matter of 

 which bricks and tiles, with the various species of pottery, and 

 innumerable other articles, adapted to promote the comforts of 

 social life, are formed. Next to this, in general, vast beds of gravel 

 appear, composed of pebbles ; varying much in their size and form : 



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