272 



PUY DE PARIOU. 



with snow. It was early in May : but the snow was gone, and grass 

 was growing in some parts ; others were covered whh loose masses 

 of scoriae. Owing to the great porosity of the soil, the crater of Pa- 

 riou seems doomed to perpetual sterility, — there is no tree or shrub 

 within it ; while that of Vesuvius, after a cessation of eruptions for 

 only four centuries, was covered with large chestnut trees." — Vol. ii. 

 page 307. 



In the Puy de Pariou, and many other volcanic mountains of this 

 district, there is nothing particularly remarkable, except, that the la- 

 vas which have flowed from them at a remote period, should .pre- 

 serve all the freshness of recent lavas, and that volcanoes so well 

 characterised, both by their forms and mineral products, should have 

 remained unnoticed until the middle of the last century. The round 

 topped or dome shaped hill on the left of the Puy de Pariou is called 

 Sarcoui ; it belongs to that class of volcanoes that have no craters, 

 which will subsequently be noticed. The more ancient volcanoes, 

 that have poured out the thick beds of basalt that cap many of the 

 valleys round Clermont, cannot always be traced, as the openings 

 from whence it issued may be covered by the lava of more recent 

 eruptions. In order to obtain a more distinct idea of the position of 

 these caps of basalt, it will be necessary to remark, that the granitic 

 plain above Clermont, and the hollows or valleys in its sides, receiv- 

 ed their present form, prior to the most ancient volcanic eruptions; 

 these hollows or ancient valleys, were probably basins or lakes, in 

 which were deposited a vast thickness of calcareous strata, contain- 

 ing fresh water shells, and the bones of land quadrupeds. Into these 

 lakes, there has flowed a vast mass of volcanic tufa, covering the, 

 limestone, and sometimes intermixed with it. The volcanic tufa,, 

 and the fresh water strata, appear to have filled up the ancient val- 

 leys or lakes ; and on this tufa, the basalt was deposited by a subse- 

 quent eruption. At a later period, diluvial currents have furrowed 

 excavations or new valleys in the basalt, in the subjacent tufa, and 

 in the fresh water limestone, leaving detached portions or hills com- 

 posed of basalt, tufa and limestone, which once were parts of con- 

 tinuous beds. Into these new valleys, the lava of the most recent 

 volcanoes has flowed. The most remarkable circumstance attending 

 these more ancient eruptions, is the bituminous nature of the tufa, 

 which forms the lowest bed, and covers the fresh water limestone of 

 Gergovia, Canturges and the neighboring hills. This tufa is, in 

 some parts, more than three hundred feet thick ; it consists of earthy 

 basalt or wacke, intermixed with lumps of scoriae and basalt, and in 

 some places, with limestone: it is every where impregnated with 

 bitumen. The tufa of Auvergne bears evident marks of being the 

 product of an aqueous or muddy eruption, intermixed with lava and 

 scoriae, which increase in quantity in the upper part of the mass, 

 and at length cover it with compact lava or basalt. That the tufa 

 was ejected in an aqueous or muddy state is proved, by the quantity 



