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TRANSACTIONS OF THE SECTIONS. 85 
distance of 18 inches, giving the rock a mottled look. In other places along the shores 
of and over Killiney Hill, the granite, at its contact with the slates, exhibits a thin 
layer of well-developed crystals of mica. 
__In our present state of information regarding the chemical or mechanical action 
which would take place in a heated granite being brought on a large scale into rela- 
tion with a cold mass of slates, it is difficult to account for the appearance which the 
granite presents at Killiney Park Quarry ; doubtless the appearance which the mica 
now presents is the result of a re-arrangement of the crystals, and is, in short, a meta- 
morphism. 
General Shetch of the Districts already visited by the Geological Survey of 
India. By Tuomas Orpnam, A.M, P.R.S., G.S., ¢.. Superintendent 
of the Geological Survey of India. 
The labours of the Geological Survey of India have been conducted hitherto under 
great difficulties. More recently, however, the liberality of the Government of India 
has greatly extended the establishment of the survey, and Mr. Oldham trusted that their 
future progress would be rapid and effective. ‘Ihe only general sketch-map of the 
geology of India which they had was that published by the late Mr. Greenough. This 
was a work of great value, and gave abundant proof of the extent and labour of its 
author in its compilation. As might be anticipated under the circumstances, it was full 
of errors; and perhaps few could speak more confidently of this than himself. But 
at the same time it was a most valuable contribution, and would prove a most useful 
guide to future observers. ‘The officer of the Geological Survey had examined several 
districts of considerable area in detached positions, and the results which he was able 
to lay before the Section might therefore appear less connected than he could wish. 
But every day would tend to unite them more closely ; and his object was now simply 
to report progress, and to show that something had been done to elucidate the struc- 
ture of India. Referring first to the districts to the east of the Bay of Bengal, the 
Tenasserim Provinces extend for about six degrees of latitude along the east shores 
of the Bay of Bengal. In breadth they seldom exceed more than one degree of lon- 
gitude. From Siam, on the east, these provinces are separated by an interrupted 
range of mountains, occasionally rising to 7000 or 8000 feet high, but the general 
height of which is to the north about 4000, diminishing in passing southwards to 
3000 feet or less. ‘The main direction of this range is north and south; this being 
also the general direction of the coast line, of the minor and outlying ranges of hills, 
and therefore of the rivers. The geological structure is tolerably simple, although 
at first sight apparently complicated, from the great disturbances to which the rocks 
have been subjected. The central range is of granite, occasionally, but not frequently 
of syenitic character; itself traversed by thick veins of large crystalline felspathic 
granite, and often along its outer edges, or near its junction with overlying slates, 
characterized by the presence of tinstone as an ingredient of the mass disseminated 
among the other mineral constituents. This granite axis is succeeded by highly 
metamorphic rocks of gneissic and micaceous character, themselves cut up by nume- 
rous veins of granite, which, however, do not extend far from the junction. Upon 
these is a great accumulation of bluish and bluish-black earthy beds, thinly laminated, 
of thin-bedded grits, and of pseudo-porphyritic rock, the normal character of which is 
an earthy hard rock with small irregularly disseminated sub-crystalline felspar, pass- 
ing, on the one hand, into slates, and, on the other, into grits, often coarse and con= 
glomeritic. These harder rocks form all the higher grounds of the outer ranges of 
hills. This series, being best seen in the southern province of Mergui, has been pro- 
visionally called the ‘ Mergui” series. The total thickness is about 9000 feet. It is 
succeeded unconformably by hard sandstones in thick and massive beds, with their 
earthy partings, generally of reddish tints, occasionally deep red and yellowish. A 
few beds are slightly calcareous, and in the upper portion a few thin and irregular 
bands of earthy blue limestone occur. Above these rest about 200 feet of soft sand- 
stone in thin beds, upon which apparently rests the massive limestone of the country 
so largely seen near to Moulmein. The thickness of the entire group is about 6000 
feet, and as some of its members are but seen in the northern province of Moulmein, 
I have provisionally called it the ‘“Moulmein” series. ‘To determine the age of the 
