ILLINOIS STATE DAIRYMEN's ASSOCIATION, 7/ 



infiltrations ; which belong respectively to the geological 

 periods of their formations, and are soils of great fertility 

 and productiveness where there is sufficient rainfall during 

 the summer and fall months. 



2nd. The formation of alluvial soils. These soils are 

 formed and deposited in river valleys by the annual over- 

 flow of rivers, by the removal of diluvial soils already 

 formed, and the decomposition of rocks on the mountains 

 and hillsides of the river sources drifting their debris or 

 sediment, intermixed with vegetable matter, and depositing 

 them in their valleys and in deltas at the mouths of rivers 

 where they discharge their waters into oceans, bays, seas 

 and lakes. These soils partake in character of all the geo- 

 logical formations from which these soils were formed, and 

 are generally rich in organic matter and mineral infiltra- 

 tions, and are the most fertile and self-sustaining of all soils 

 known ; as in the valley of the Nile, Ganges, Rhine and 

 valleys of rivers in North America. All taken together 

 cover large tracts of country. 



3rd. Soils of volcanic origin. The soils derived from 

 volcanic action are of much less extent than either of the 

 former ones. They have their origin wholly by the melting 

 of the primitive rocks by intense subterranean heat and vol- 

 canic action. These melted rocks form lava, ashes and 

 pumice, which are raised and forced through the craters of 

 volcanoes during their eruptions, running down their 

 mountain sides into the valleys and plains below them, and 

 forming soils partaking of the character of all the rocks 

 forming these soils. Volcanoes were more numerous and 

 eruptions more frequent in early periods than at present. 

 The soils derived by volcanic action are generally, where 

 there is sufficient rainfall, moderately fertile, as attested by 

 the magnificent forests grown on these soils in Oregon, 

 Washington Territory and British Columbia. 



The intrinsic value of volcanic action during past ages, 

 in contributing means for the advancement of modern civ- 

 ilization cannot be fully estimated. By its action mountain 

 ranges have been elevated. Their rocks have been tilted, 

 bent, twisted and displaced, and their precious metals and 

 mineral treasures have been revealed and made accessible 

 to the ingenuity of men and used for the purpose of com- 

 merce and mechanical arts. All this in addition to the for- 

 mation of valuable soils for agricultural purposes. 



