184 7-J Notes t chiefly Geological, from Goofy to Hydrabad. 4$v 



has its rise, and course, entirely in a granite country before it passes 

 through the great black soil or regur plains of Bellary — whose granite 

 and gneiss are also the principal rocks. 



The surface soil from Hydrabad southerly to the Kistnah near 

 Myapore, is generally a reddish alluvium, sometimes more or less sandy, 

 or clayey, according to the prevalence of felspar or quartz in the adja- 

 cent rock. It varies from the zero of the bare rock to 12 feet in 

 thickness. Sometimes a bed of kunker, (from 6 inches to 2 feet thick) 

 intervenes between it and the rock ; but more frequently the loose 

 gravelly debris of the subjacent granite or gneiss, which is extremely 

 prone to decay on exposure to the air, or to moisture, whether from 

 springs or rivers. 



Where subterranean springs exist this bed of Mhnrrum, as it is called, 

 is sometimes from 30 to 50 feet thick ; but, more commonly, water is 

 found at depths from 6 to 30 ft. Springs impregnated with calcareous or 

 saline matter seem to eifect the breaking up of the rock to a greater 

 extent than those of pure water. 



Mr. Malcolmson,* in speaking of this granitic debritus, thus observes : 

 f ' It has been stated by Dr Christie, that this debris is, at a considerable 

 depth, again consolidated by pressure. In the Edinburgh Journal of 

 Science, 1828-9, this is also mentioned as a fact, common to the rocks 

 of other parts of India. With every respect for his authority, I cannot 

 avoid the conviction, that the inference was founded on imperfect obser- 

 vation, and that it has since been employed in Europe, in support of 

 an ill-founded theory. The ' Mhurrum' or gravel found in deepening 

 a well at Bolarum (6 miles from Secunderabad) upwards of 50 feet deep, 

 during the dry season of 1832, is not in the slightest degree conso- 

 lidated." " Much of the debris of Secunderabad is, however, consoli- 

 dated by lime, which is seen to agglutinate the fragments, or to pass 

 in vein-like lines or nodules through the gravel. Occasionally there 

 are only a few fragments of quartz or felspar scattered through the 

 kunker, or they appear to be inserted into the surface." " The debris 

 is also sometimes united into pulverulent masses, by the oxidation of 

 the iron contained on the sienite ; but this takes place at the surface, 

 and seldom acquires any degree of hardness." 



While perfectly coinciding with the general accuracy of my lamented 



* Madras Journal, July li',36, p. 198. 



