On the Neighbourhood of Bombay, and certain beds containing Fossil Frogs

Abstract

The island of Bombay is composed of five or six bands of trap rock, chiefly greenstone and amygdaloid, conformable, and dipping west at about 10° or 15°, and separated by beds that have every appearance of being of sedimentary origin, though there is no actual proof of the fact. The highest and most western of these beds have been laid open in some engineering operations, and in these the fossils sent to the Society have been found. The batrachian beds are a mass of blue rock, weathering into a shale not unlike ordinary coal shale, and containing what I have no doubt will turn out to be vegetable impressions. The upper beds are interstratified with thin seams of sandstone and argillaceous rock, and over the whole is a mantle of basalt which cannot have been less than 70 feet thick. This basalt has in parts caused imperfect fusion of the fossil beds, obliterating their stratification and superimposing something of its own columnar, or at least prismatic structure. These fossil were discovered, a few days ago, by Dr. Leith of the Bombay Service, and as he is an acute and diligent observer and well-acquainted with his subject, I think, before very long, these beds will be thoroughly investigated. I am preparing an account of the geology of the island, but it is so closely connected with that of the main land, that I am loath to say much upon the one until I am better acquainted with the details of the