ON THE FACTS AND THEORY OF EARTHQUAKE PHENOMENA, 131] 
The magnitude of the wave raised is dependent upon that of the mass of solid 
material that has suddenly changed its place, upon the depth of water in which the 
Fig. 10. 
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slippage has occurred, upon the rapidity of the transposition, and in a minor degree 
upon the form and material of the portion of the bank that has slipped. Where the 
depth of water is very great, its effects at the surface may be quite insensible at the 
place; but when this low broad flattened wave of only a few inches becomes heaped 
up on shelving shores or tidal estuaries, it may then become very apparent, and 
perfectly so to accurate tide gauges. Where the water is comparatively shallow, 
as it usually is where large and heavy banks occur, there the undulatory effects on 
the surface, even at the seat of disturbance, will be considerable. We have then 
a simple mechanism abundantly sufficient to account for the occurrence of some 
such abnormal tide-waves or great sea-waves as have been noticed ; but while thus 
a vera causa, is it the cause of any of those phenomena that have been observed, 
and which do not appear to have been accompanied by earthquakes? This, as well 
as all the hydrodynamic phenomena of such sea-waves, I would commend to the 
careful attention of future observers. (See First Report, p. 61.) 
Stoppage of Rivers.—Throughout earthquake narratives, nothing is more commonly 
recorded amongst the secondary phenomena, than sudden derangements of the ordinary 
and prior regimen of springs, wells, and especially of rivers. Almost all such facts admit 
of simple explanation ; and in the case of rivers, the sudden drying up or stoppage of 
their streams, has been most usually due to sudden damming up by the fall of débris 
of rocks from precipices, &c. across the river-beds, usually at narrow gorges, where 
the damming can easily take place, and whence it is, by the posterior rising of the 
waters, afterwards swept away or gradually removed by floods, &c.; often also on a 
granderscale,it arises from the occurrence of greatlandslips (in countries of deep alluvial 
or other little coherent formation), bulging out into the river-beds, and temporarily 
shutting them up, and either forcing the streams into new channels, or damming 
them up until the waters produce a debacle and sweep away the obstacle. 
But not a few cases are upon record of sudden stoppages in the ordinary supply 
of water in river streams, not known to have been connected with any earthquake, 
or with any sufficient and explainable cause. Perhaps the phenomena cannot be 
more briefly set forth than by transcribing a notice from ‘Chambers’s Edinburgh 
Journal’ for Jan. 19, 1839, No. 364. p. 412 :— 
“Late Stoppage of Rivers in the South of Scotland.—Most of our readers have 
probably read the accounts which appeared in the newspapers of a simultaneous 
stoppage of the rivers Teviot, Clyde, and Nith, on the 27th of November last; yet, 
as many may not have heard of it, and few may have paid to it the attention which 
it deserves, we are glad to have the opportunity afforded us of bringing the circum- 
stance under the especial notice of our readers. It has, we are glad to find, been 
taken up, as a subject worthy of scientific investigation ; and in this we have been 
_ invited to assist, by endeavouring to procure information from any of our readers 
who may be able to affordit. The phenomenon, it is suspected, is attributable to 
some agent or cause which had acted over a very extensive range of country, and 
which, probably, produced similar effects, in many other places besides the banks 
of the three rivers above specified. We trust that if such effects were perceived by 
any of our readers, they will be so obliging as accede to the proposal and the request 
_ with which we conclude the present notice. 
“On the morning of Tuesday, the 27th of November last, about six o’clock, the 
miller of Maxwellheugh Mill, situated on the Teviot, near its confluence with the 
_ Tweed, perceived a great diminution taking place in the water which flowed through 
his mill-course. At eight o’clock the water altogether ceased to flow. Thinking 
that the sluice had fallen down, or that the cauld [dam] had given way, he went up 
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