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On the Principal Depressions on the Surface of the Globe. 

 By Dr George Buist, Bombay.* 



In the following admirable digest, extracted from the Bom- 

 bay Times (Sept. 28th 1854), it is apparently merely for the 

 sake of simplicity, and for a convenient starting point, that 

 the author supposes that " the earth assumed its present cha- 

 racter and conformation," either by having " risen directly," 

 or " through a long series of elevations," so that the streams 

 that drain its surface, and the waters in its inland hollows, are 

 the result of one or of a series of actions of upheaval, accom- 

 panied, however, by " stupendous disturbances and frightful 

 distortions amongst the rocky beds ;" which " must have oc- 

 curred at the time of their elevation," these being followed by 

 " change and commotion" on a minor scale, examples of which 

 occasionally occur, even down to the present day. 



Since the revival of the doctrines of Hutton, geologists have 

 been gradually abandoning the idea of vast disturbances and 

 changes, caused by the exercise of forces more sudden and 

 stupendous than those of which we have experience ; and it is 

 held by many, that the surface configuration of existing con- 

 tinents is the result of the complicated action of numerous 

 gradual upheavals and depressions, and long-continued marine 

 and atmospheric denudations ; during which, through the va- 

 rious epochs of geological time, the same mountain chains 

 were formed by repeated disturbances, strong, though slow in 

 their operation. Hence, some of them in their earlier stages, 

 formed the nuclei of existing continents, while other ancient 

 ranges and tracts of land of continental extent, now form at 

 least part of the bed of the ocean. The existing drainage of the 

 world is therefore not simply the result of recent great changes 

 of the outlines of the terrestrial surface ; but the origin of 

 many of our systems of drainage, and perhaps even in some 

 cases of individual rivers, must be sought for in disturbances 

 connected with geological epochs, often far removed. The 

 same is true in a minor degree of areas of depression. 



* Read to the Bombay Geographical Society, Sept. 14, 1854. 

 NEW SERIES. VOL. I. NO. II AriUL 1855. 8 



