*56 NORTHERN CHILE. [CHAP. xvi. 



at Coquimbo : they immediately cried out, " How fortunate ! there will 

 be plenty of pasture there this year." To their minds an earthquake 

 foretold rain, as surely as rain foretold abundant pasture. Certainly it 

 did so happen that on the very day of the earthquake that shower of 

 rain fell which I have described as in ten days' time producing a thin 

 sprinkling of grass. At other times, rain has followed earthquakes, at 

 a period of the year when it is a far greater prodigy than the earthquake 

 itself: this happened after the shock of November, 1822, and again in 

 1829, at Valparaiso; also after that of September, 1833, at Tacna. A 

 person must be somewhat habituated to the climate of these countries, 

 to perceive the extreme improbability of rain falling at such seasons, 

 except as a consequence of some law quite unconnected with the 

 ordinary course of the weather. In the cases of great volcanic erup- 

 tions, as that of Coseguina, where torrents of rain fell at a time of 

 the year most unusual for it, and " almost unprecedented in Central 

 America," it is not difficult to understand that the volumes of vapour 

 and clouds of ashes might have disturbed the atmospheric equilibrium. 

 Humboldt extends this view to the case of earthquakes unaccompanied 

 by eruptions; but I can hardly conceive it possible, that the small 

 quantity of aeriform fluids which then escape from the fissured ground, 

 can produce such remarkable effects. There appears much probability 

 in the view first proposed by Mr. P. Scrope, that when the barometer 

 is low, and when rain might naturally be expected to fall, the diminished 

 pressure of the atmosphere over a wide extent of country might well 

 determine the precise day on which the earth, already stretched to the 

 utmost by the subterranean forces, should yield, crack, and conse- 

 quently tremble. It is, however, doubtful how far this idea will 

 explain the circumstance of torrents of rain falling in the dry season 

 during several days, after an earthquake unaccompanied by an eruption ; 

 such cases seem to bespeak some more intimate connection between 

 the atmospheric and subterranean regions. 



Finding little of interest in this part of the ravine, we retraced our 

 steps to the house of Don Benito, where I stayed two days collecting 

 fossil shells and wood. Great prostrate silicified trunks of trees, 

 embedded in a conglomerate, were extraordinarily numerous. I 

 measured one, which was fifteen feet in circumference : how surprising 

 it is that every atom of the woody matter in this great cylinder should 

 have been removed and replaced by silex so perfectly, that each vessel 

 and pore is preserved ! These trees flourished at about the period of 

 our lower chalk; they all belonged to the fir-tribe. It was amusing to 

 hear the inhabitants discussing the nature of the fossil shells which I 

 collected, almost in the same terms as were used a century ago in 

 Europe, namely, whether or not they had been thus "born by 

 nature." My geological examination of the country generally created a 

 good deal of surprise amongst the Chilenos : it was long before they 

 could be convinced that I was not hunting for mines. This was some- 

 times troublesome. I found the most ready way of explaining my 

 employment was to ask them how it was that they themselves were not 

 curious concerning earthquakes and volcanoes ? why some springs were 



