so Reviews — Geological Society's Journal. 



him in physical structure, and living in sucli a climate and with 

 such surroundings as alone would suit primeval man. At all events 

 there is clear evidence that the present order of things had set in from 

 a very remote period in India; and certainly less disturbance of surface- 

 conditions has occurred there during Pliocene times than in Europe, 

 Northern Asia, and North America, to interfere with the growth of the 

 human species, or to remove the evidences of man's early presence. 

 This paper on the ancient fluviatile deposits of the Nile and Ganges 

 has a melancholy interest in being the last of its lamented author's 

 works ; and it has a high value as presenting the matured results of 

 close observation and serious thought on the question of man's 

 antiquity, first entertained by Falconer and Cautley in 1835, and in 

 nowise invalidated by subsequent reflection and research. It is a 

 legacy of clear notions and sound doctrine ; and it prophesies a sure 

 finding of fossil man in tropical and subtropical regions, when sought 

 for with close scrutiny and keen intelligence. 



From a renewed examination of the raised beach and overlying 

 chalk -rubble in the cliff at Sangatte, near Calais, Mr. Prestwich gets 

 further evidence of the Channel Straits having existed when the 

 older alluvia of the Somme and Thames were formed, and of other 

 old geographical conditions. 



Messrs. Foster (D.Sc.) and Topley, both of the Geological Survey, 

 have contributed a valuable paper on the river-gravel and brick- 

 earth of the Medway Yalley, and on the Denudation of the Weald 

 by the action of rain and rivers. They clearly describe the Medway 

 Valley and its alluvia ; and they prove that some of its old river- 

 gravel lies at a level of 300 feet above the present river-bed. If so, 

 and if (as is fairly argnied) there are many great difficulties in the 

 way of accepting marine denudation as the cause of the Wealden 

 hollows, then, with long time, rain and rivers could and must have 

 washed away the missing material from the whole of the Wealden 

 area. The geological surveyors show a real desire to search out and 

 give credit for what has been already done and thought of; still we 

 may remind them that the subaerial dissolution of chalk-land is not 

 to be found for the first time in the Geological Survey Memoirs, and 

 that Mackie's hypothesis of a tidal occupation of the Wealden, pre- 

 vious to the formation of the Channel-Straits, is quite worth a 

 passing notice. We must admire their clear and comprehensive 

 treatment of the features of the North Downs and the Weald ; but 

 we cannot understand how they can shut their eyes to the coinci- 

 dences of river-courses and faults on their own fine map ; nor why 

 they decry the mathematical hypothesis of the Wealden Yalleys. 

 Even the Preston section, with its bold flexures of Eag-stone, fades 

 away with them into a note of interrogation (p. 459). We really 

 must accept rain and rivers as steady, hard-working, and therefore 

 important agents (and some of the very elements of their physics are 

 given in the paper under notice) ; but we are disinclined to say 

 where on a rising land the action of the sea ends and that of the rain 

 begins ; and we are still less inclined to believe that England was 

 ever so free from faults, that the trickling rain, or sweeping 



