51 



ON THE GEOLOGICAL CHARACTER AND DISTRIBUTION OF THE SOILS 

 IN THE UNITED STATES. 



While there is a vast variety of detail in the character of the soils of 

 this country in regard to both their physical properties and chemical 

 composition, still they may be classified under the two heads of soils 

 of transport and soils of disintegration, geologically speaking. 



Soils of transport include, as has been previously stated, all drift and 

 alluvial materials which have been worn from other rocks by atmos- 

 pheric agencies and transported to their existing positions by ancient 

 glacial action, by winds, and by waters. These embrace the majority 

 of all soils occurring in the United States. 



Drift soils. These occupy the principal portion of the States lying 

 north of the Ohio and east of the Missouri Rivers. According to Pro- 

 fessor Dana, they occur " over all New England and Long Island, 

 New York, New Jersey, and part of Pennsylvania, and the States west, 

 to the western limits of Iowa and Minnesota. Beyond the meridian of 

 98 W., in the United States, they are not known. They have their 

 southern limit near the parallel of 39, in Southern Pennsylvania, 

 Ohio, Indiana, Illinois, and Iowa, whilst their northern is undetermined. 

 3-iutb of the Ohio River they are hardly traceable."* 



Without going into the details of the theory of ancient glacial action, 

 which has given rise to a large amount of study and an extensive litera- 

 ture, the term drift, as it is commonly employed in geology, includes 

 the sands, gravels, clays of various composition and texture, and bowl- 

 ders, more or less water- worn, all mingled in various proportions and of 

 various degrees of fineness, which have been transported from places 

 in higher latitudes by glacial action and deposited on the country rock 

 in varying thickness. 



The soils of this drift are usually gravelly, often stony, of variable 

 fertility, from the noted fertile lands of Ohio and Western New York 

 to the barren portions of New England. As a whole, these soils grow 

 finer as they go further southward and westward from New England 

 and Western New York. When overcropped and worn out, as often 

 happens, they lecover when allowed to rest fallow several years by 

 the decomposition of the mingled materials of which they are composed. 



Alluvial soils. These are formed from the deposits of the fine earthy 

 materials, sediment, silt, or detritus, by running streams and rivers, 

 of which we have such a notable example at the Mississippi's Delta. 



The amount of transportation going on over a continent is beyond calculation ; 

 streams are everywhere at work; rivers, with their large tributaries and their thou- 

 sand little ones, spreading among all the hills and to the summits of every mountain. 

 And thus the whole surface of a continent is on the move toward the oceans. The 

 word detritus means worn out, and is well applied to river depositions. The amount 



* Dana's Geology, p. 528. 



