OF THE LEVEL OF THE SEA. 65 



marks of violence as are indicated by extensive inclinations 

 of the stratification, or by the fractures, erosions, and un- 

 stratified deposits which have been produced by diluvial 

 agency, it is quite evident that some of these changes must 



having generalized too hastily on diluvial phenomena, geologists began 

 to run into the other, of endeavouring to exclude diluvial action from 

 the list of geological agencies, — to expunge the very name from geolo- 

 gical nomenclature, — to forget all the evidence which had been col- 

 lected of the passage of large bodies of water over the land, and, in 

 every mass of transported gravel in which marine shells of existing 

 species were discovered, to see a raised beach, or a marine formation, 

 of gradual accumulation, regardless of the proofs which, in many cases, 

 existed of such deposits being due to the sudden and transient action 

 of the sea." It is impossible to examine the diluvial deposits which I 

 have formerly noticed, without remarking the evident effects of such 

 sudden and transient action, so perfectly resembling those which we 

 know must have been owing to similar causes. In the summer of 

 1818, I had an opportunity of observing the deposit caused by the ir- 

 ruption of the lake which had been formed by a glacier in the Valley 

 of Bagne, and which was spread over the valleys of the Dranse and the 

 Rhone, before it was covered by vegetation or obliterated by cultiva- 

 tion. No word could so well express its appearance as " diluvium," ex- 

 cept that the occurrence of works of art formed a prominent feature, 

 especially below the village of Martigny, where several houses were 

 destroyed, and where beams, hewn stones, and fragments of furniture, 

 were confusedly mixed with gravel and clay. At Greenock, in 1834, 

 I witnessed the effects of an inundation, caused by the breaking down 

 of the head of a reservoir,' in which upwards of thirty lives were de- 

 stroyed. In its track to the sea, it exhibited all the phenomena of di- 

 luvial action. The streets and walls were marked with furrows ; masses 

 of stone, an"d even of cast-iron, were mixed up with clay and gravel 

 without regard to their gravity ; whilst within the houses every thing 

 was covered with a thick layer of fine silt, exactly as in the diluvial 

 caves. Were this covering, therefore, to occur in insulated patches, we 

 might seek in similar causes for similar effects ; but where could the 

 lake have existed so vast as to have swept away nearly the whole of 

 the alluvial covering of the great coal basin of Scotland from sea to 

 sea, and lodged it in one confused mass in some places hundreds of feet 

 in thickness ? Its cause must, I apprehend, be sought for in some sud- 

 den geological action of a magnitude far surpassing any like event re- 

 corded in the short page of human history. The long continued action 

 of submarine currents could not have been the cause of the beds in 

 question, although I have no doubt that they often have given origin 

 to coarse beds of gravel improperly -"termed diluvium. 



VOL. VIII. E 



