no A. B. "Wynne — Notes on an Eartlgtiahe in tlie Punjrfh. [No. '^, 



cutting off limestone mountains from others formed of slate. Rawalpindi 

 is on a plateau formed of tertiary rocks, alternating sandstones and clays, 

 just there nearly vertical and horizontally overlaid by post-tertiary and 

 perhaps even newer clays, sands, and boulder-beds. Lahore and Ferozpur 

 are on the alluvial Punjab plains. 



In most of these places, the shock occurred at the same time, as nearly 

 as can be judged, and its results were similar, whether it lasted under two or 

 as much as five minutes. 



Kohat, close to east and west ridges of limestone or of sandstone, 

 and standing upon a stony detrital deposit at the mouth of the Hangti 

 valley, is about 80 miles due west of Rawalpindi : in both places the 

 undulation approached from the westward, in the latter more nearly west- 

 north-west. 



Simla is entirely differently situated from these stations ; at a great 

 elevation and nearer to crj^stalline masses which would probably afford a 

 better conducting medium for the earth-waves. Yet here the time of the 

 occurrence was presumably the same as elsewhere, and though the move- 

 ment is said to have come from oi3posite directions and to have lasted fully 

 nine minutes, I have no evidence that the damage caused, which would be a 

 measure of the force exerted, was at all greater than at Abbottabad or 

 other localities, 



I have heard it more than once observed that these Punjab earth- 

 quakes usually occur after rain has succeeded a spell of fine weather ; 

 indeed Dr. Henderson tells me that from this he predicted the occurrence 

 of the earthquake previous to that of March 2nd, felt at Rawalpindi as 

 well as by myself in Hazara. With reference to this point it should be 

 remembered that the nine distinct shocks which I have mentioned as having 

 recently occurred in the Punjab within- fifty-three days, hav^e followed a 

 season of excessive rainfall preceded by an exceptionally and disastrously 

 dry summer. 



Whether the access of meteoric water by gravitation through the 

 rocks to hotter regions below be a sufficient cause in the present case for 

 the phenomena observed, or a better one can be suggested, I must leave for 

 the enlightened consideration of competent seismologists ; and though 

 several minor shocks are not unusual attendants upon a greater earthquake, 

 I venture to suggest that something exceptional in the way of cause must 

 have occurred to account for the greatly increased frequency of late of the 

 earthquakes in the Punjab, where they have rarely taken place more than 

 once in a twelvemonth, at least for the last nine years : and also for the 

 greater than usual intensity which has marked one of them, almost simul- 

 taneously felt over an area, which may be roughly estimated at G7,000 

 square miles. 



