332 tiOW CROPS FEED. 



large a part of the Middle State?, bxxt most of the rocks 

 of New England have been soil, and have supported vege- 

 table and animal life, as is proved by the fossil relics that 

 have been disinterred from them. 



We have explained the agencies, mechanical and chemi- 

 cal, by which our soils have been formed and are forming 

 from the rocks. By a reverse metamorphosis, involving 

 also the cooperation of mechanical and chemical and even 

 of vital influences, the soils of earlier ages have been so- 

 lidified and cemented to our rocks. Xor, indeed, is this 

 process of rock-making brought to a conclusion. It is 

 going on at the present day on a stupendous scale in vari- 

 ous parts of the world, as the observations of geologists 

 abundantly demonstrate. If we moisten sand with a so- 

 lution of silicate of soda or silicate of potash, and then 

 drench it Avith chloride of calcium, it shortly hardens to 

 a rock-like mass, possessing enough firmness to answer 

 many building purposes (Ransome's artificial stone). A 

 mixture of lime, sand, and water, slowly acquires a simi- 

 lar hardness. Many clay-limestones yield, on calcination, 

 a material (water-lime cement) which hardens speedily, 

 even under water, and becomes, to all intents, a rock. 

 Analogous changes proceed in the soil itself Hard pan, 

 which forms at the plow-sole in cultivated fields, and 

 moor-bed pan, which makes a peat basin impervious to 

 water in beds of sand and gravel, are of the same nature. 



The bonds which hold together the elements of feldspar, 

 of mica, of a zeolite, or of slate, may be indeed loosened 

 and overcome by a superior foi-ce, but they are not de- 

 stroyed, and reassert their power when the proper cir- 

 cumstances concur. The disintegration of rock into soil 

 is, for the most part, a slow and unnoticed change. So, 

 too, is the reversion of soil to rock, but it nevertheless 

 goes on. The cultivable surface of the earth is, however, 

 on the whole, far more favoi-able to disintegration than 

 to petrifaction. Nevertheless, the chemical affinities and 



