Secretary's Budget. 385 



ACTIOX OF AIR, WATER, AXD FROST. 



That the agencies just described may seem to many persons 

 far too weak and slow in their action to give rise to soils of such 

 depths as are found in many localities, is very probable. Espec- 

 ially will this be the case with those living in the northern and 

 eastern states, where, in ancient times, the great ice-sheet called a 

 glacier has scraped tlie tops of the hills entirely bare and left them 

 hard, barren, and apparently indestructible. But "firm as the 

 everlasting hills,^^ is only a poetic expression. From a geological 

 standpoint hills are neither firm nor everlasting. The great 

 destroyer. Time, is as relentless in his dealings with rocks and hills 

 as with human beings ; it is but a question of time and nothing 

 more. Let any one examine for himself the soil, accumulated at 

 the foot of a large mass of roek, of whatever kind, and he will 

 find it to consist of small fragments of the same material as the 

 rock itself, mixed with particles of decaying wood and leaves. Or 

 if he live in the southern states, beyond the limits of the glacial 

 or ice action, he may be able, in any deep road or railway cut, to 

 trace the gradual jjassage downward from flue, loose soil to hard, 

 compact rock. 



There are many places in Maryland and Virginia where the 

 observA' may easily trace this transition, and in one locality which 

 the writer has in mind, a hard, tough rock, composed almost 

 Avholly of quartz and mica, has become so rotten for a deptli of 

 nearly eighty feet below the surface, as to be readily dug up with 

 pick and shovel. The resultant soil, it is interesting to note, is 

 not remarkable for its fertility. 



SEDENTARY AND DRIFT SOILS. 



Since, then, there are many different kinds of rocks, so, also, 

 there are many different kinds of soils ; but geologically they mav 

 all be grouped under two heads, the distinction being based upon 

 their methods of formation. The first of these are called " sedent- 

 ary soils," (sedentary from the Latin seder e, to sit,) that is, soils 

 resulting from the decomposition of rocks in situ, and which have 

 never been removed by water or ice from the portions in which 

 they originated. Such soils necessarily agree closely in composition 

 with the rock which they overlie. 



They are perhaps more common in the southern than in the 

 northern states, cover a more limited area, and, in some cases, 

 contain a much larger proportion of organic, or vegetable matter 

 than those included under the second head, which are called drift 



