Notices of Memoirs — Indian Geoloyy. 379 



IV. — Recobds of the Geological Survey of India. 

 Vol. III. Part 1. February, WO.— {Continued from p. 341.) 



THIS Part of the Eecords contains — in addition to Dr. Oldham's 

 Annual Eeport noticed in our last number — p. 339, 



2. Notes on the Geology of the Neighbourhood of Madras. By E. Bruce 



Foote, Esq. 



The district under consideration lies to the north of the river 

 Palar, and south of the Pulicat lake. The topographical features 

 are simple : the ground rises from the coast westward in a gradually 

 inclined plane, varied only by the shallow valleys of the Narnave- 

 ram, Cortelliar and Palar rivers, and in the south-eastern comer by 

 a number of low hiUs. Eoughly speaking, the northern, central, 

 and south-western parts of this area are occupied by stratified rocks, 

 the southern and south-eastern by metamorphic rocks. The follow- 

 ing is a table of the rocks noticed in the neighbourhood : 



P + ;i ( Blown sands. 



itecent ana ] ^n^^-^^^^ marine, and fluviatUe. 



\4\x emary. ^ j^q^^j^iq and Conjeveram gravels. 



Tertiary. Gritty sandstones. (? Cuddalore sandstones.) 

 Q , ( (Cretaceous, not yet known in the area), 

 teecondary. j j^^assic, Eajmahal plant-beds. 

 Sub-metamorphic. Cuddapah group. (Quartzite rocks). 

 Metamorphic. Gneissic series. 

 The Laterite deposits comprise clayey conglomerates, gravels, and 

 sands, which graduate one into the other. They rarely attain a 

 thickness of 12 feet. They are scattered over the higher grounds 

 between the river valleys, and have evidently been separated by 

 denudation into patches, some of small size, others attaining one and 

 two hundred square miles in extent. The laterite gravels contain 

 pebbles of quartzite and gneiss, mixed with pisiform ferruginous 

 pellets. 



The Conjeveram gravels occupy similar positions to the lateritic de- 

 posits, but they differ from these in the absence of ferruginous 

 matter. Both appear to contain implements of human manufacture, 

 in the shape of axes and spear-heads made of chipped quartzite peb- 

 bles, and of the same types as those which occur in the gravels of 

 Western Europe. 



The Rajmahal beds consist of conglomerates, sandstones, gritty 

 clays, and shales. Numerous plant remains have been found in some 

 of the clay beds, and particularly in a white shale. These remains 

 include Palceozamia, Dictyopteris, Taxodites (?), Pterophyllum, Tceniop- 

 teris (?), Stangerites, Pecopteris, Lyeopodium (?), axL^iPoaeites. Several 

 genera of Mollusca have likewise been obtained from these beds ; they 

 include — besides several small Ammonites — Leda, Toldia, Tellina, 

 Psammobia Lima^ Pecten, etc. 



3. On the Alluvial Deposits of the Irawdd'i, more particularly as con- 

 trasted with those of the Ganges. By W. Theobald, Jun., Esq. 



In every large river basin two distinct alluvial deposits will 



