OCT. — DEC. 1856.] of the Southern Division. 93 
of titanium in nodular concretions of recent limestone are found 
here. 
The same kind of granite as mentioned above is found to under- 
lie all this region to within about 10 miles of the Coleroon ; in some 
places it is associated with the common granite as its frequent 
outcrop and disintegrating fragments in the soil plainly show. 
Nearly all the mountains and hills, however, and most of the vast 
blocks that nearly cover the surface in. some places are syenitic. 
The granite near the river Colerooh is of the common kind and 
highly porphyritic. ^ 
At the junction of these two kinds of granite and crossing the 
road from Madras to Trichinopoly, near the 182nd mile stone from 
the former place, is a bed of finely and evenly stratified grey sand- 
stone. The strata are from 2 or 3 inches to joth of an inch in 
thickness, and they separate with a fracture so smooth and even 
that the pieces resemble smooth plates of slate. A specimen ob- 
tained there is about 2 feet long, one foot wide and 1 inch thick 
and nearly as even and smooth as a board. The small crystals of 
felspar contained in it are of the orthaclase species, and of a dull 
flesh colour. 
The extent of this bed has not been ascertained; it has been 
traced, however, more than a mile in length, but the width of the 
outcrop is not more than 10 or 15 yards ; and it runs in a direction 
nearly east and west. The strata on the south side of the bed are 
crossed by joints which pass through it nearly parallel to each other 
and about two feet apart and at an angle of about 50° with the 
line of direction ; the dip of the strata appeared to be about 60® 
on the south side and nearly 20° in the centre, while that of the 
north side was not satisfactorily determined. A singular charac- 
teristic of this bed is, that the strata on the south side of it are 
composed of nearly pure silicious sandstone ; in the middle they 
were porphyritic, containing felspar, while those on the north side 
were composed almost entirely of a greenish black hornblende, 
these thin strata forming a beautiful hornblende slate. This ap- 
peared to be the junction of the two minerals hornblende and mica ; 
to the north of this, hornblende, either in a free state, or combined 
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