374 
THE TERTIARY VOLCANOES 
BOOK VIII 
tion, but were essentially superficial, and were protruded to the surface at 
various points along the plateau in the midst of already existing cinder- 
cones. In some cases, they have risen on or near the position of the vents 
of these cones. Thus the Puy de Cliopine is half encircled by the crater of 
the Puy de la Goutte, and the Grand Sarcoui stands in a similar relation to 
the fragmentary crater-wall of the Petit Sarcoui. 
M. Michel Levy, in pointing out the superficial character of the 
domitie protrusions, has forcibly dwelt on the evidence that these rocks have 
undergone a comparatively trifling denudation, and that they could never have 
extended much beyond their present limits. 1 As Scrope pointed out, they 
were obviously protruded in a pasty condition, not flowing out in streams 
like the other lavas of the district, but consolidating within their chimneys 
and rising from these in rounded domes. 
Undoubtedly denudation, cannot have left them altogether unaffected, 
but must have removed some amount of material from their surface. There 
is reason to believe that the material so removed may have been in large 
part of a fragmental character, and that it was under a covering of loose 
Fig. 344. — Section through the Puy de la Goutte and Puy de Chopine. 
1, Mica-schist ; 2 2, Granite ; 3 3, Tuffs ; 4, Trachyte ; 5, Basalt dyke. 
pyroclastic debris that the upward termination of the trachyte column 
assumed its typical dome-form. Thus in the crater-wall of the Puy de la 
Goutte, layers of buff-coloured trachytic tuff dip gently away from the central 
domite mass of the Puy de Chopine. That this material was thrown out from 
the vent previous to the uprise of the domite may be inferred from the way in 
which the latter rock has obliterated the northern half of the crater. The 
relations of the rocks are somewhat obscured by talus and herbage, but when 
I last visited the locality in the spring of 1895 the structure seemed to me 
to be as expressed in the accompanying diagram (Pig. 344). 2 
The relative date of the protrusion of the trachytic domes cannot be 
very precisely defined. There can, indeed, be no doubt that it belongs to a 
late phase of the volcanic history. It came long after the outpouring of the 
older basaltic plateaux, of which large fragments emerge from beyond the 
limits of the younger lavas on both sides of the great ridge of the puys, and 
not only long after that outpouring, but even after the widespread sheets of 
basalt had been deeply trenched by valleys and isolated into outliers capping 
the hilltops. Yet there is good evidence also that the uprise of the com- 
1 Op. eit. p. 711. 2 Compare M. Michel Levy, ibid. 
