1833.] ‘Second Report on the Geology of Hyderabad. 401 
basalt which passes into wacken, containing stilbite, mesotype, icthyoph- 
thalmite, heliotrope, calcedony, green earth, quartz with cr ystals of 
calcareous spar imbedded, the form of which the quartz has taken, 
demonstrating that this mineral has been the last deposited. The 
wacken passes into iron clay, and in some places the basalt may be seen 
with the wacken and iron clay in the space of afew yards. The latter 
forms elevated table land at Béder, which is 2,359 feet above the level 
of the sea; it closely resembles that of the red hillsat Madras, Nellore, 
Singhirikunda (in the two latter on granite), all on the sea coast, but in 
this instance rests on basalt. I observed in it plumb blue lithomarge, 
and pisiform iron ore. 
On the basaltic hill of Medkunda I observed large masses of flint 
lying on the surface and deeply connected ; also pieces of a siliceous 
stone, containing shells which had lost their carbonic acid: the external 
surface of these masses effervesced in acids. These shells belong to 
the genera turbo and cyclostoma, and living specimens are found in 
the beds of most of the rivers as well as on the rocks in their neigh- 
bourhood. The specific gravity of these stones varies from 1:90 to 
2-00, that of the flint is 2°60. A few miles from this place I observed 
the same shells enclosed in small pieces of earthy limestone; they were 
lying on the basalt, which is here 2000 feet above the level of the sea 
and about 200 above the river Manjira: the base of the hill being 
granite, and the basalt not occupying more than 100 feet. 
Quartz rock occurs in the granite in beds, as at Pitlam, Gazypet, 
and in the environs of Hyderabad : the rock in the neighbourhood of 
the latter is elevated 40 or 50 feet above the level of the plain through 
which it runs; its course is north and south, and its extent about twelve 
miles. It contains considerable quantities of amethystine quartz, which 
is not pure enough for the purposes of the lapidary. 
- The loose masses of quartz, as well as those which appear above the 
surface, have a rhomboidal form. This rock runs directly opposed to 
the greenstone veins, and intersects three of them. I have reason to 
believe that the trap passes through the quartz, although I have not 
yet distinctly observed it, except in one instance near Hyderabad. 
Clay Slate. ~ 
The clay slate which is found to the eastward of Hyderabad, between 
Byardm and Paltinshah, is about 20 miles in breadth and perhaps 30 
miles in length, with a north and south direction. One of its highest 
points, Panch-bondal, is 2600 feet above the level of the sea. The 
valleys contain sandstone, clay slate, and quartz rock ; this eee 18 also 
found on the summits in yeins and beds, 
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