48 On the Excavation (yf Valhys. 



C pitchstone. 

 D D D D gneiss. 

 E River ArdSche. 



Longitudinal Section of the Plain of tlie Allier at Issoire to Perrier and Pardines. 

 A oldest tertiary grit (gi-anite of certain Frencli authors.) 

 B tertiary lacustrine marls. 

 C older alluvium, Boulade bone-bed. 

 D D trachytic breccia. 

 E alluvium (bone-bed.) 

 F newer alluvium. 

 G land-slip. 

 H compact basalt. 



PLATE III. 



Transverse section of the various deposites on the north bank of the Couze at Perrier. 



N. S.— All the tufaceous and alluvial beds, viz. from 1 to 9 inclusive, 

 dip slightly to the east ; whilst the inferior or tertiary lacustrine de- 

 posites dip from 10° to 15° W. S. W. 



1. Trachytic conglomerates, identical in character with those of Mont Dore, 



Monton, &c. Total thickness 250 feet. 

 • Fossil bones in alluvium, according to Messrs Jobert and Croizet. 



2. Brecciated tufaceous conglomerate of a light grey colour. 20 feet. 



3. Black brecciated tufaceous conglomerate, filled with large blocks of dark 



compact basalt. The old cast le is built on this. 



4. "White pumiceous trap. 



5. Bed of rounded pebbles. 



<J. Tufaceous trachytic conglomerate, with scoriae and fragments of granite 

 and amygdaloid. 



7. Pumicose grit. 



8. Alluvium in very regular beds, containing much volcanic rock and thin 



laminae of filamentous pumice, granite, quartz, &c. sand and gravel of 

 various colours alternating. Contains some bones, 50 feet. 



9. Coarser alluvium than No. 8., resting unconformably on the lacustrine 



deposites, boulders of from six to nine inches. Contains fossil bones, 

 20 feet. 

 •• Lignite of Messrs Jobert and Croiset. 



10. Tertiary lacustrine deposites consisting of thirty laminated shaly marls, 

 containing cypris, &c. alternating with compact green and yellow marl, 

 strong beds of limestone, bluish unctuous marls, thinly laminated 

 white and green marl, with bands of fetid limestone. 140 feet. 



t Village of Perrier. 



