288 



THE EEGOLITH 



ties, and many names have, on one ground and another, been ap~ 

 plied to its local phases, the more important of which are given in 

 tabular form below, and described in detail in the pages following. 

 According to its origin, whether the product of transporting 

 agencies as noted above, or derived from the degeneration of 

 rocks in situ, the regolith is found lying upon a rocky floor of 

 little changed material, or becomes Jess and less decomposed 

 from the surface downward until it passes by imperceptible 

 gradations into solid roek. 



The ^ 

 regolithl 



Sedentary 



Transported ^ 



Subdivisions of the Eegolith 



{Eesidiiary gravels, sands and 

 clays, waeke, laterite, terra 

 rossa, etc. 



Cumulose deposits i Peat, muck, and swamp soils, in 

 ^ X part. 



n-.n„,.;«i .i«^««*4.« i Talus and cliflf debris, material 

 CoUuvxal deposits j ^^ avalanches. 



An,„r;„i ^„^««,-+= fMoclern alluvium, marsh and 



anSn^^^^^^ '^^^^ (P^l^^^^l) ^^eposits,tlie 



Cmemcung aqueo -j Qi^amplain clays, loess, and 



glacial) 





adobe, in part. 



'ind-blown ma 



dunes, adobe and loess, in part. 



Glacial d*^T»nait<» i Morainal material, drumlins, es- 

 iiriaciai aeposits ^ ^^^^^ ^^^^^^ ^^^^ 



^olian deposits | Wind-blown material, sand 



The extreme upper, most superficial portion of this regolith, 

 that which affords food and foothold for plant life, is commonly 

 designated as soil; that immediately underlying the soil, and 

 passing into it by insensible gradations, is known as the sub-soil. 

 This last differs from the soil proper only in degree of compact- 

 ness and in such chemical changes as may have been induced 

 in the soil through growing organisms and more extensive 

 weathering. Indeed, the soil is but derived from the sub-soil, 

 and were it entirely removed, would shortly be replaced through 

 the same agencies as first gave it birth. 



The characteristics of individual soils can best be discussed 

 when speaking of those local phases of the regolith of which 

 they form a part, and with this understanding we will proceed. 



1. SEDENTARY MATERIALS 

 Here are to be considered those deposits which, resulting 

 from chemical decomposition or disintegration, from any or all 

 of the processes involved in rock-weathering, or from organic 

 accumulation, are found to-day occupying their original sites. 

 They are, in fact, the primeval types of nearly all soils and sec- 



