i Guettard in Auvergne 37 



been his delight when he saw below him the smooth-sloped 

 hollow of the crater, not now belching forth hot vapours and 

 ashes, but silent and carpeted with grass ! For centuries 

 the shepherds had pastured their flocks on these slopes, 

 and the quarrymen had been busy cutting and sending off 

 the lava for roads and buildings, but no one had ever 

 suspected that this quiet and lonely spot retained such 

 striking monuments of subterranean commotion. 



Descending to the great lava-stream, Guettard scruti- 

 nized its structure as laid open in the quarries, and at 

 once noticed how different in character it was from any 

 other rock he had ever seen in France. He observed it 

 to be divided into sheets inclined with the general slope 

 of the ground, but separated from each other by layers of 

 clay, earth or sand, as in the case of sedimentary forma- 

 tions, yet solid, and breaking easily in any direction, so 

 as to lend itself readily to the arts of the stone-mason. 



Travelling southward along the base of the picturesque 

 ridge of the Puys, Guettard and Malesherbes reached 

 Clermont, where they procured the services of an intel- 

 ligent apothecary, who had some knowledge of the topo- 

 graphy of the hills. They climbed the steep slopes of the 

 Puy de Dome a hill made famous by Pascal. Every- 

 where they noticed volcanic debris partially concealed 

 under vegetation. If the view from the first volcano 

 above Volvic delighted the travellers, we can imagine 

 their amazement and pleasure when the marvellous pano- 

 rama around the highest craterless summit spread itself 

 like a map around them. As their eyes ranged over that 

 array of old volcanoes, so perfect in form that it is difficult 

 to believe them to have been silent ever since the begin- 



