604 



DELUGE. 



Oeluge. Disputes have arisen among philosophers respecting 

 w -V— * the veference of these appearances to a deluge, and the 

 mode in which that agent might be brought into action 

 by natural causes. We propose in a future article to 

 enter pretty fully into the subject, when a greater num- 

 ber of facts shall have been collected and arranged. In 

 the mean time, we are desirous of calling the attention 

 of geologists to it by noticing, very shortly, the opi- 

 nions of the few who have written any thing in this 

 wide field of inquiry. 



M. de Saussure, during his examination of the AJps 

 of Switzerland, was forcibly struck with the appear- 

 ance of blocks of granite, which had evidently belong- 

 ed to the central ridge, lying scattered on the sur- 

 rounding mountains and on the neighbouring valleys. 

 To remove these blocks from their parent rock, and to 

 transport them across deep and wide ravines, and over 

 the summits of intervening mountains, seemed to re- 

 quire an agent of no ordinary power. The transporta- 

 tion of these blocks, Saussure ascribes to a vast torrent, 

 which he imagined had, at a remote period, swept the 

 earth, overtopping the Alps, and carrying masses of 

 the rocks along with it. To this supposed torrent he 

 applies the term debacle, a French word which is some- 

 times made use of to denote the clearing of a harbour, 

 by setting at liberty a collection of water to sweep 

 away the alluvial matter obstructing it. Our English 

 word deluge, we consider more expressive of the ex- 

 tent of such a torrent as would be necessary to produce 

 the effects in question. 



While De Luc admits the debacle of Saussure, he 

 ascribes the position of the blocks of granite to a cause 

 which could have a place only in the most fantastic 

 imagination, and which it is needless for us to detail. 

 Neither of these philosophers appeal- to have digested 

 their ideas of a deluge so perfectly, as to warrant their 

 entering on any explanation of its cause, or even afford- 

 ing any precise idea of their notions respecting its ope- 

 rations when produced. Pallas, in his Observations sur 

 la formation des Montagues, ascribes the production of 

 the deluge, which he supposes to have transported the 

 remains of animals of one climate to another, to the ac- 

 tion of volcanoes under the sea. 



These speculations have remained almost unnoticed 

 till lately, when Sir James Hall brought the subject 

 before the Royal Society of Edinburgh, in a form more 

 likely to attract attention. That gentleman has for 

 many years been engaged in tracing what he con- 

 ceives to be the effects of a powerful torrent, that has 

 swept across Scotland from west to east. He has hi- 

 therto confined his researches to the vicinity of Edin- 

 burgh ; and has accurately pointed out various places, 

 where scratches and furrows on the surface of the rock 

 are to be seen, and which are worthy of minute ex- 

 amination. These effects he ascribes to the attrition of 

 the stones carried along by a deluge. Whoever exa- 

 mines the deep mass of gravel, sand, stones, and clay, 

 ■which, in almost every country, covers the surface of 

 the rock, acknowledges immediately that it has been 

 deposited by water. But with respect to the manner 

 ki which the water operated, different opinions are en- 

 tertained. 



This subject does not seem to have been of sufficient 

 importance to arrest the attention of the Wernerian 

 school. The followers of Hutton are divided on this 

 question; and while some of them assert, that the 

 •rdinary diurnal operations of the atmosphere and the 

 action of rivers, are sufficient to account for all that has 

 1 



been observed, others maintain, that something more is Deluge- 

 required. — ,- v 



Sir James Hall appeals to the efforts of subterra- 

 neous heat acting under compression, as supposed by 

 Dr Hutton, and endeavours to illustrate the mode in 

 which he imagines a wave of sufficient magnitude to have 

 been produced. We believe it to be now universally ad- 

 mitted, that concussions of the earth are occasioned by 

 the exertion of an elastic fluid bursting the rocks which 

 confine it. Sir James Hall supposes that such an exer- 

 tion, by heaving up the superincumbent mass, and dis- 

 placing a body of water, which is also impelled up- 

 wards by the concussion, would produce a wave on the 

 surface of the sea. An earthquake felt on the coast, i9 

 commonly attended first with a retreat of the water 

 from the shore ,• an effect which Sir Jame3 Hall ac- 

 counts for, by the rising of the wave immediately above 

 the place where the subterraneous force exerts itself. 

 After this retreat, the water returns with great violence, 

 and overwhelms every thing in its progress. These 

 effects are illustrated by events during the earthquakes 

 at Cadiz, Lisbon, and Callao. But the most remark- 

 able, and the one which applies most strictly in il- 

 lustration of Sir James Hall's ideas, is that related by 

 Humboldt, of a large tract of ground, extending to 

 three or four square miles, called the Malpays, in South 

 America, having been raised, during an earthquake, to 

 the height of 524 feet. This might have happened at 

 the bottom of the sea, and there can be no doubt of 

 similar events taking place in that situation. 



Experiment has been resorted to by Sir James Hall ; 

 and by exploding gunpowder under water, he succeed- 

 ed in producing in miniature, precisely the same effects 

 which he supposed would arise from the concussion 

 of an earthquake in the sea. 



Having thus attempted to explain the means by 

 which a vast wave, sufficient to overtop the mountains, 

 might be raised, Sir James calls in the aid of glaciers, 

 to assist in transporting large masses of stone from one 

 place to another. It is well known that the glaciers of 

 the Alps, and the Icebergs formed every winter at the 

 mouths of the great rivers in the northern regions of 

 America, envelope immense collections of stones. It is 

 supposed that if a torrent of water broke it up, the ice 

 would float along with its load, and deposit it gradual- 

 ly as it advanced and melted. The extraordinary blocks 

 of granite on the shores of the Baltic may thus, it is 

 supposed, be accounted for, as well as those of the Alps. 

 We do not intend at present to discuss the hydrosta- 

 tical accuracy of Sir James Hall's theory. But we may 

 state, that an operation, the very reverse of that which 

 he supposes, would produce a wave without any devia- 

 tion from the laws of hydrostatics, and account for all 

 the appearances observed during earthquakes. Instead 

 of the land rising, we may suppose it to burst, and lay 

 open extensive hollows, into which the water would 

 rush, filling up the vacuum occasioned by the escape or 

 condensation of the elastic vapours which caused the 

 fracture. Powerful currents would immediately be 

 produced, all tending to a centre; and the velocity ac- 

 quired would be such, that, after the vacuity was filled, 

 the collision of so many currents at one point, would 

 raise the water to a great height. The retreat of the 

 water from the shore might be explained as well in this 

 way, as by supposing the bottom of the sea to have 

 been raised. The heaving of a mass of land entirely 

 out of the sea, or its sudden submersion, would also 

 produce great agitation in the water; and in every case 



