428 PHYSICAL GEOGRAPHY. 



cones, craters, volcanic hills and mountains, which have discharged their red-hot streams 

 of lava, and showers of ashes, at some former period of the history of the globe, the anti- 

 quity of which, the application of thousands of years will go but a little way to measure. 

 This district has been attentively examined by Mr. Bakewell and Mr. Poulett Scrope, 

 whose memoirs upon it are full of interesting and striking facts to the physical inquirer. 

 It was not till the year 1751 that the existence of this volcanic region was known, when 

 M. Guettard and a companion naturalist, returning from Vesuvius, stopped to botanise 

 upon the mountains in Auvergne, and were surprised at the resemblance they bore to the 

 Italian volcano, and at the similarity of the lavas and minerals in both. The valley of 

 Clermont exhibits a series of fresh-water limestone strata upon a substratum of granite, 

 which appear in the surrounding hills interposed between the granite and volcanic rocks ; 

 but, ascending towards the west, all traces of the limestone disappear, and the volcanic 

 rocks rest immediately upon an elevated granitic plain. From this plain a number of 

 conical and dome-shaped mountains rise, the highest of which the Puy de Dome 

 celebrated by the barometrical experiments of Pascal, ascends 3451 feet above the town 

 of Clermont, and 4797 feet above the level of the sea. Some of the mountains preserve 

 the forms of well-defined craters, from which currents of lava may be traced descending 

 into the present valleys. The crater of the Puy de Pariou, 3800 feet above the level of 

 the sea, is as perfect as that of any recent volcano, and from it, or from the flanks of the 

 mountain, a lava current has streamed, now lying upon the plain, from thirty to sixty feet 

 thick, covered with scori3 and basaltic lava. All the accompaniments of volcanic action, 

 with the exception of the phenomenon of an actual eruption, are found in Auvergne in as 

 perfect a manner as at Etna and Vesuvius, in the Lipari Islands and Iceland ; and the 

 interposition of stratified formations among the volcanic products show different and 

 distinct periods separating the eruptions from each other. The lavas have been cut by 

 the action of rivers, which have not only exposed the columnar basalt which now forms 

 the precipitous walls of their channels, but have eaten their way into the granitic rock 

 beneath, these excavations having of course been executed subsequent to the eruptions 

 which poured the fiery floods into the valleys. ""Yet when did these fires burn ? When 

 took place this amazing Combination of volcanic eruptions and their terrible accompani- 

 ments ? How long ago was the last of them ? And by what interval of time could we 

 ascend, from that last, to the earlier eruptions, and to the earliest of the astounding 

 number ? " It is certain that we must go by several thousands of years at least to arrive 

 at the era of the last disturbance. 



The general history of Europe contains no record of any volcanic eruption in Auvergne, 

 nor does any thing occur in any rhyme or legend of the monkish chroniclers from which 

 it might be inferred. Some, indeed, have deemed it not improbable that in a thinly 

 inhabited country like that of the mountain parts of this province, the volcanoes might 

 have been in action after the fall of the western empire, without being noticed or known 

 by the historians of the barbarous ages, when men were too earnestly engaged in 

 destroying each other, or in providing for their own safety, to bestow much thought on 

 natural phenomena. But this supposition will not bear examination, for monastic pens 

 were busy enough at the time in question ; and to surmise the occurrence of such physical 

 convulsions in the heart of Gaul, without the rumour of them gaining a wide circulation, 

 and long surviving jn the traditions of the locality, is obviously extravagant. Going 

 farther back, we find Cassar encamped at Gerzovia in this very district during his Gallic 

 wars ; yet, though his Commentaries show that he surveyed the country with a careful eye, 

 he mentions no volcanic outbreaks, nor records any tradition picked up in the neighbour- 

 hood of such events having formerly occurred. But the water- worn lavas conduct us 

 much farther back into the past. It requires a long period for the action of a river to cut 



