Mr Smith on the Changes of the Level of the Sea. 391 



not observe any such marks of violence as are indicated by ex- 

 tensive inclinations of the stratification, or by the fractures, 

 erosions, and unstratified deposits which have been produced 

 by diluvial agency, it is quite evident that some of these 

 changes must have been sudden ; and beds of testaceous ani- 

 mals have been entombed alive by the subsequent deposit of 

 clay or sand from a considerable depth. This is particularly 

 observable in the laminated clay in which marine remains are 

 so frequently found in the basin of the Clyde. The upper parts 

 seem quite destitute of them, and it is only when the excava- 

 tions are made deep enough, such as in digging wells or coal- 

 pits, or in the lower beds of brick- works, that they may be ex- 



discovered, to see a raised beach, or a marine formation, of gradual accu- 

 mulation, regardless of the proofs which, in many cases, existed of such de- 

 posits being due to the sudden and transient action of the sea." It is im- 

 possible 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 si- 

 milar causes. In the summer of 1818, I had an opportunity of observing 

 the deposit caused by the eruption 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 oblite- 

 rated by cultivation. No word could so well express its appearance as di- 

 luvium, except 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, 1 witnessed 

 the eflfects of an inundation, caused by the breaking down of the head of a 

 reservoir, in which upwards of thirty lives were destroyed in its tract to 

 the sea. It exhibited all the phenomena of diluvial action. The streets 

 and walls were marked with furrows, masses of stone, and 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 in one confused mass in some places hundreds of feet in 

 thickness ? It must, I apprehend, be sought for in some sudden geological 

 action of a magnitude far surpassing any like event recorded 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. 



