BROWN AND YELLOW LOAM OF NORTH MISSISSIPPI 275 



are liable to be found, in smaller numbers, wherever the Brown 

 Loam occurs, and one will rarely travel far in the loam region 

 without finding them. They seem to be entirely characteristic 

 of the Brown Loam in this vicinity, not being found in any of the 

 older formations on which it directly rests — that is, as far as my 

 observation extends — and over most of the territory the loam 

 is itself the surface formation. It is true that along streams 

 frequently "second bottoms" are to be found (sometimes as 

 "buckshot" lands), and the more recent alluvial deposits, the 

 latter, however, never containing concretions : but the former 

 are undoubtedly, in many cases, merely terraces of degradation 

 cut in the Brown Loam, when, because of increased velocity due to 

 increase of slope or to decrease of burden, or to both, the streams 

 began to erode the bottoms of their channels more rapidly than 

 their sides, and so ceased to overflow only within the past 

 twenty-five or thirty years. 



But it is not always an easy matter in the field to separate 

 the loam from more recent formations. This subject will be 

 more fully treated under the head "Upper Limit in the same 

 Region." 



These "buckshot" are usually more or less rounded, yellow- 

 ish-brown on the oxidized surface, black in the interior, possess- 

 ing no definite structure, and ranging in size from that of a small 

 shot to that of a small marble. Not infrequently, however, they 

 are much larger, when they usually tend to become more flat- 

 tened and angular, and are frequently found cemented by iron 

 oxide into a rather friable conglomerate. 



These ferruginous concretions have undoubtedly been formed 

 by segregation from the mass of the loam, as have somewhat 

 similar ferruginous concretions and the calcareous nodules from 

 the loess, and especially the friable conglomerate already men- 

 tioned, has evidently been cemented in situ. (Compare paragraph 

 338, p. 199, Agriculture and Geology of Mississippi. ,) Typical spec- 

 imens of the "buckshot" from the loam of Tate county, ground 

 up together and analyzed at my request by Mr. Charles Strong 

 afforded : 



