PART 1.] 
Geology of the neighbourhood of Madras. 
11 
Turin. —Royal Academy of Sciences. 
Victoria. —Royal Society. 
„ Philosophical Institute. 
„ Govt. Geological Survey of Victoria. 
Vienna. —Kais. Akad. der Wissenschaften. 
„ K. K. Geologische Reichs-Anstalt. 
Washington. —Smithsonian Institute. 
Governments of India, Madras. Bombay, Bengal, N. W. Provinces, Punjab; Chief Commis¬ 
sioners, Oude, Central Provinces, British Burmah. 
Notes on the Geology of the neighbourhood of Madras, —by R. Bruce Foote, Esq., 
F. G. S., Geological Survey of India. 
The greater part of the Madras district lying north of the Palar river and south of the 
Pulicat lake is occupied by rocks of the secondary, tertiary, and recent ages, the remainder 
of the area being taken up by metamorphic rocks forming part of the great gneissic series 
of Souther* India. 
The topographical features of this part of the Carnatic are very simple, the ground 
rising from the coast westward up to the foot of the Eastern ghats and their outliers, in a 
very gradually inclined plane which I will call the Madras area. The surface of this plana 
is varied only by the shallow valleys of the Narnaveram, Cortelliar, and Palar rivers, the 
latter forming the southern boundary of the tract of country now under consideration. In 
the north-western part of the district the inclined plane is broken by two groups of hills, 
the Sattavedu and Alicoor hills, to the west and north-west of which, but just beyond the 
boundary of the country now to be described, rise the Naggery mountains, which are lofty 
and conspicuous, but perfectly detached outliers of the Eastern ghats. The south-eastern 
corner of the inclined plane is dotted by a number of low, but picturesque, ridgy gneiss hills. 
The northern, central, and south-western parts of the Madras area are occupied by the 
stratified rocks, roughly speaking, the southern and south-eastern parts by the metamorphic 
rocks, a narrow belt of which must be included all round the western boundary of the 
area of the stratified rocks. 
Classification of the Rocks. 
The following tabular statement illustrates the various groups into which the rocks of 
the Madras area have been classified t— 
( Blown sands. 
Recent or quaternary ... -< Alluvium, marine, and fluviatile. 
(Laterite and Conjeveram gravels. 
Tertiary ... ... Gritty sandstones. ? Cuddalore sandstones. 
Secondary /(Cretaceous?) 
y ... ... ^Jurassic, Rajmahal plant beds. 
Submetamorphic ... Cuddapah group. 
Metamorphic ... ... Gneissic series. 
The Blown Hands .—Those sub-aerial deposits are of no great extent or importance, 
as they form merely a fringing ridge to the beach. To the south of Madras they are largest 
at, and to the south of, Covelong (Kovilam of the natives). North of Madras they attain 
their greatest height, between 40 and 50 feet, at a place called Chintamanikovil, where they 
have nearly covered up the Kovil (Hindu temple). 
The greatest width attained by this coast ridge may be about a mile, but it is generally 
much less, and the amount of drifting inland is not of any real importance, and easily 
stopped by plantations of suitable trees, e. g., Casuarinas, Palmyra palms, Screw pines, and 
Cashewnmt trees, all of which flourish near the coast. 
The alluvial formations .—These are of two classes, marine (including estuarine) and 
fluviatile, but they are nearly undist-inguishable in character, and at many points graduate 
into each other imperceptibly. 
