284 NOTE ON THE LATEUITE OF OEISSA. 



broken, to consist mainly of concretionary peroxide of iron, with fre- 

 quently small angular pieces of clear quartz, but more frequently of 

 a mottled rock, which is evidently decomposed gneiss. Probably the 

 more ferruginous concretionary masses are the same, but changed in ap- 

 pearance by being more strongly impregnated with iron. 



The deeper the section, the less appears to be the quantity of iron, 

 and the smaller the number of ferruginous lumps. 



Its passage into gneiss 



or other nietamorphic until at length the bed passes into a white clay 

 rocks. . . . , „ 



conlammg particles ot quartz and felspar, folia- 

 tion then becomes gradually apparent, and no doubt can remain that 

 the formation ia the result of the alteration, in situ and by surface action, 

 of a metamorphic rock. Indeed the change only differs from the usual 

 course of conversion -of a felspathic rock into kaolin, in the peculiar 

 impregnation with iron, and the tendency to a segregation of that iron, 

 in the less decomposed portions of the mass.* 



Sections are occasionally seen in wells, in which the quartzose layers 

 of the metamorphic rocks extend vxnaltered into the argillaceous mass 

 of " Laterite," which has been formed by the decomposition and altera- 

 tion of the more felspathic portions, and in one particular instance, near 

 Paikesae, a village a little west of the Dyah rivei-, a section was se^n, 



* Fresh sections of laterite are naturally not easily found ; those available being 

 chiefly wells in process of sinking, and, a^ the water which usually rests upon the 

 lower and most argillaceous portion of the decomposed gneiss is, in most cases, reached at 

 a small depth, they are seldom of much value. Old sections are of no use, for reasons- 

 which are mentioned further on. Many of the above details were first observed at a well 

 and boring at Daltola, near Khurdah, which was made by Captain Harris, the Sui've3'or 

 of Cuttack rivers, who very kindly supplied me with specimens taken at short intervals 

 in the depth. The well was dug to a depth of 26 feet, when water was reached, and then 

 a boring was sunk nearly 50 feet further. The upper 6 feet was formed of the nodular 

 and sandy upper deposit, below 6 feet the argillaceous lower form of laterite came in, and 

 was, at the top, dark red in colour, at 12 feet reddish brown, at 20 feet dark yellowish 

 brown in part, light yellow in others, at 25 feet all yellow or white. The boring from 

 below this shewed a gradual passage into gneiss, buHhe unaltered r£>ck was not reached. 



