198 



Notes on Geological Specimens from 



must state, that being in Medical charge of the European regiment, 

 during a sickly s-eason, I could not command my own time of marching, 

 or sufficient leisure. 



The character of the granite of the Beccan continues well marked 

 throughout the remaining part of the route to Hyderabad, and dykes 

 and imbedded masses of a fine crystalline greenstone or hornblende 

 rock of great hardness are frequently seen. These last have occasion- 

 ally irregular shapes, and in one or two instances, that of the italic 

 or other irregular curve ; and near Secunderabad, they appear to be 

 connected with the dykes, in the neighbourhood of which they are 

 found. It was also frequently observed that the various substances 

 entering into the composition of the granite in the neighbourhood of 

 these dykes or masses, formed very large and distinct crystals ; and 

 the imbedded greenstone, though often intimately united with the 

 granite, was in others more loosely connected, and easily separated by 

 the progress of decomposition, leaving rounded cavities in the rock. 



A circumstance of more importance, however, is the occurrence of 

 the beds of kankarin this tract, being, as far as I have observed, al- 

 ways near some of the greenstone dykes or beds, and frequently under 

 or intermingled with masses of granite, which is in a rapid state of 

 decay : these are usually rounded, partly from the progress of decom- 

 position, and sometimes from the tendency to concentric forms, which 

 it occasionally undoubtedly assumes. The small detritus is in some 

 places accumulated to a great depth, and it has been stated by Dr. 

 Christie, that this debris is, at a considerable depth, a gain consoli- 

 dated by pressure. In the Edinburgh Journal of Science, 1828-29, 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 con- 

 viction, that the inference was founded on imperfect observation, 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 Bo* 

 laram, (six miles from Secunderabad), upwards of 50 feet deep, 

 during the very dry season of 1832, and is not in the slightest degree 

 consolidated. A loose block, which had resisted decomposition, was 

 found above it, and contains mica, a rare ingredient in the gra- 

 nite of Hyderabad. Much of the debris at Secunderabad is, how- 

 ever, consolidated by lime, which is seen to agglutinate the fragments, 

 or to pass in vein-like lines or nodules through the gravel. Occa- 

 sionally there are only a few fragments of quartz or felspar scattered 

 through the kankar, or they appear to be inserted into the sur- 

 face, which is extremely hard. Generally, however, the agglu- 

 tinated gravel is friable, and the cement less obvious. The debris is 

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



