274 T. O. MABRY 



I. GENERAL CHARACTERISTICS OF THE BROWN OR 

 YELLOW LOAM. 



The predominant material of the formation in this section to 

 which Hilgard has applied the name of brown loam, or yellow 

 loam is as he states [Agriculture and Geology of Mississippi, p. 

 198), "that of a mellow clay or loam, without any definite 

 structure or cleavage, variously tinged with iron ; containing 

 from 10 to 25 per cent., usually, of siliceous sand, the rest being 

 clay mixed with finely divided silica, and forming, therefore, 

 rather loose, mellow soils, and good brick clays. 



The loam proper of this formation varies from the brownish- 

 black color of our richest upland soils, where the coloration is 

 due largely to the presence of organic matter through yellow 

 and red, to the grayish- white "buckshot," or "crawfish," lands, 

 which are ill suited to agricultural purposes. 



In view of the immense value of these "buckshot" (which 

 characterize the lands of that name by their presence in large 

 number) to the geologist in enabling him to identify with reason- 

 able certainty loams of this period occurring in this region, a 

 brief description of them will not be out of place. They are not 

 confined to the so-called "buckshot" or "crawfish" lands, but 



through the counties of Tishomingo, Prentiss, Union, Lee, Pontotoc, Lafayette, 

 Yalobusha, Panola, Tate, Marshall, and De Soto in Mississippi, and Shelby county, 

 Tennessee. 



In its preparation invaluable aid has been received from the writings of Hilgard, 

 McGee, Chamberlin, and Salisbury. To my former instructors in field geology, 

 Messrs. A. P. Brigham, H. B. Kiimmel, and T. C. Chamberlin, credit is due for val- 

 uable training in field methods ; to Professors Chamberlin and Salisbury I am also 

 indebted not only for instruction in the theoretical aspects of the science, but for sug- 

 gestions as well, given both in and out of the class room, bearing upon the subject 

 under discussion ; and to Professor Chamberlin I am under special obligations for a 

 critical review of the first draft of this article. 



Thanks are also due to Mr. Charles Strong, M.A., former Fellow in Chemistry, 

 University of Mississippi, for a chemical analysis of "buckshot " from the yellow loam; 

 to Dr. F. H. Knowlton, for the identification of fossil plants herein described,'and to 

 various others for kindnesses shown me. 



But for the collection and collation of data on which this paper is based, and for 

 the conclusions derived therefrom, I alone am responsible. The accompanying photo- 

 graphs were taken by Sanders and Sweeney, Oxford, Mississippi. 



