Chapter VI. — Snj)erficial DejjosUs and Soils. 

 Among superficial deposits thei'e are three more especially deserving 

 of notice^ becauscj though they often occupy merely the position of sur- 

 face soils^ they often also attain to such extent and thickness as really 

 to demand the rank of geological formations; and further, they are 

 almost peculiar to India. These are Laterite, Cotton Soil, and Kunhur. 

 In the country we are describing, laterite occurs more particularly 

 L terite associated with the post-cretaceous rocks ; and on 



already treated of. ^j^-g account we have described this rock in the 



Chapter devoted to them. The peculiar phenomena observed in connec- 

 tion with cotton soil will be touched upon when treating of soils consi- 

 dered with reference to agriculture. 



The greyish -white calcareous deposit generally known under the 

 name of kunkur occurs commonly over the whole 

 country, generally as little grains or concretions, 

 or small agglomerations of such in the soil ; very often also as a travertin- 

 like deposit on the surface of the rocks in river beds, where it occa- 

 sionally forms the matrix of coarse conglomerates and breccias. Less 

 frequently it is to be seen as the result of decomposition in situ. 



This rock in some respects resembles laterite in its mode of occur- 

 rence. It exists in like manner under two differ- 

 ent forms, which are the result of deposition from 

 water in the one case, and of decomposition of the rock in situ in the 

 other. 



The first form is kunkur proper, and is more commonly observable 



as a semi-concretionary deposit of a white, grey, 



concretionary kunkur. ■,• ^ , ^ ^ j. i <? j • . i 



or light brown colour on the smiaces and m the 



joints of rocks, particularly on the banks or in the beds of streams. The 

 concretions are essentially composed of carbonate of lime, in a matrix 

 of the same mineral ; but small grains of quartz and gneiss often re- 

 place these. Another form of occurrence is that of single pisolitic grains^ 

 ( 342 ) 



