1845.] On Kunker formations, with Specimens. 443 



On considering the shapes of the granulated masses, they will be 

 found to resemble the figures assumed by molten lead when plunged into 

 water. The substance appears to be generally clay and carbonate of 

 lime : the latter falling away freely under the action of the furnace, and 

 leaving the clay in the form of a hardened mass more or less vitrified. 



The formation of Kunker appears to me to be affected by the infiltra- 

 tion of rain water impregnated with lime through a bed of clay ; to be 

 in fact Tufa deposited in clay, or a sponge of clay saturated with the 

 carbonate of lime. 



When the heavy rains of the monsoon fall upon a soil of alternate 

 sand and clay strata impregnated with lime, the water easily soaks 

 through the loose texture of the gneiss sand, taking up with it a cer- 

 tain proportion of the lime in its passage. But on meeting the closer 

 substance of the clay stratum it there stagnates for a while, and each of 

 these clay strata becomes as it were the bottom of a subterranean lake, 

 the absorption here being very gradual and difficult, and the water 

 parting with its lime to the clay, ere it can be effected. 



When the lime is contained by the soil in large quantity, and the 

 clay stratum is dense or the duration of the deposit very long, conflu- 

 ent Kunker will be formed ; chiefly in the sandy stratum, but upon that 

 of the clay : and should (if this surmise be just,) contain a larger pro- 

 portion of sand than the granulated varieties. 



When lime prevails in mixed soils of clay and sand, not distinctly 

 stratified, the Kunker is found in very small grains dispersed confusedly 

 through the mass. These seem to be formed by isolated drops of water 

 impregnated with lime, which gradually filtering have deposited each a 

 nucleus of lime, that yearly enlarges by fresh incrustations ; but very 

 gradually, owing to there being no general arrest of the impregnated 

 water. This minute Kunker forms the sand (so to speak,) of many of 

 the streams of Central India. 



Kunker yields almost the only lime used in Upper India by builders. 

 The quality yielded by various strata is very various : often it is ex- 

 cellent, but never perhaps equal to that of the more solid limestones, 

 or of the superficial Tufa deposited by streams. 



It may appear improbable to some, that rain water should so readily 

 absorb lime, or so easily part with it ; but it is perfectly consistent with 

 observed phenomena. In Malvva where the substratum for 1500 feet is 



