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PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [June 25, 



The regular slope of the plains of Northern India up to the Siwalik 

 Hills, which rise suddenly from the flat ground, leads me to infer 

 that the sea must have continued to reach at least as far as the foot 

 of the Siwalik Hills for some time after their upheavement. 



The rise of the Tibetan plain has not been caused by the granite 

 eruption of the line of snowy peaks. That the greenstone rocks, that 

 abound in many parts of it, have equally not caused it, is proved by 

 the peculiar nature of the valleys among the hills to the west of the 

 lakes, which must have been laid out level under water ; from which 

 it is to be inferred that these eruptive rocks are older than the ter- 

 tiary beds of the plain. The same thing is shown by the occurrence 

 of worn pebbles of greenstone in the surface of the plain in the vicinity 

 of some of the detached hills of that rock. 



The former extension of the glaciers far beyond their present limits 

 is a phenomenon that may be noticed almost everywhere in these 

 mountains, and may give rise at first sight to an idea that there may 

 here also have been some special period of cold corresponding to the 

 glacial epoch of Europe. But it seems, I think, more probable that 

 this is here only the result of a change of climate consequent on 

 the upheaval of the great plains of Northern India. 



The existence of ancient moraines on the tertiary plain of Tibet 

 proves that the extension of the glaciers is post-tertiary. Now, if we 

 conceive that after the rising of this plain to nearly its present eleva- 

 tion, the sea still continued to wash the foot of the Siwalik Hills, as 

 I have already said that I considered likely, it is clear that the climate 

 of the Himalaya would have been far more moist, and that the quantity 

 of snow that fell on the highest parts of the mountains would have 

 been greatly in excess of what now falls there, causing a great exten- 

 sion of the glaciers beyond the limits to which they have now receded. 



5. Notices of the Geology of the Straits of Singapore. By 

 J. Ii. Logan, Esq., F.G.S., M.R. Asiatic S., Corr. M. Ethnologi- 

 cal Soc, and Batav. Soc. Arts and Sc. 



[Pl. XVIIL] 



Introduction. — Under this name I shall describe not only the rocks 

 in the Straits of Singapore and along its shores, but also all those 

 comprehended within a rhomboidal space, about sixty miles long and 

 thirty miles broad, of which the northern boundary is a line stretch- 

 ing E. by N. across the Malay Peninsula, from the Straits of Malacca 

 to the China Sea, and touching the most northerly part of the Old 

 Strait of Singapore ; the southern boundary being a line in the same 

 direction, touching the most southerly part of Tilo' Sumpat, on the 

 north coast of Bintang, and stretching across that island and all those 

 west of it to Phillip's Channel. The investigation of the geology of 

 the Malay Peninsula could not begin at any other place so favourable 

 for observation, for instead of the dense jungle which everywhere else 



