GEOLOGY OF THE VEZERE. 31 



Sandy alluvium, irregularly bedded here and there, lies on the side of the hill, 

 up to and beyond the cave, and contains numerous large pebbles of quartz, 

 quartzite, and schist ; but there is little or no alluvium on the upper part of the 

 hill, where the limestone is nearly bare, and only a few scattered pebbles occur. 

 Some weathered blocks of iron-ore (brown hematite) lie on the hill-top, probably 

 the debris of some Tertiary beds (such as I of the Map and Section). 



A specimen of thin-bedded, yellow, marly, fossiliferous limestone, also from 

 some part of the above-mentioned hill near Condat, bears on the planes of 

 bedding numerous small Bivalves resembling Buvignier's Lucma Mosensis* from 

 the Upper Coral-rag of Saint-Germain. A larger Bivalve and some small Oysters 

 occur in the same block of stone. 



The Cretaceous Hocks (k). A hard, pinkish-white, compact limestone, oolitic 

 (or rather pseud-oolitic) in structure, containing remains of Corals, Polyzoans, 

 Rhynchonella, &c., is quarried south of the Condat Railway-station on the right- 

 hand (west) bank of the river, for road-metal and other purposes ; and one band 

 at least of this limestone yields a small Echinoderm, probably identical with 

 Nucleolites oblongus, Desor, which is found in the ' Senonian ' stage of the Chalk 

 (Upper) in the North of France. This limestone seems to be one of the lowest in 

 the Cretaceous series at this place, and to be succeeded upwards by the limestones 

 that are met with nearer Montignac, which, in their turn, are covered to the 

 south-west by higher strata. The limestones being all whitish and nearly hori- 

 zontal, the cliffs of the river-bluffs seem at first sight to be formed of the same 

 great strata ; but descending the Vezere we come to newer and newer beds. 



Near Montignac we find Rudistes in the talus of the cliffs ; and a coarse, friable 

 sandstone, like the Quadersandstein of Germany, caps the cliff not far from the same 

 place. A thick Polyzoan limestone has also set in near Montignac (reminding 

 us of the similar rock of Touraine, Maestricht, and Eaxoe), and continues, by 

 Moustier, to Les Eyzies. Ostrcea vesicularis, O. carinata, Rhynchonella alata, 

 and Trigonia are found in the cliffs between Le Moustier and Les Eyzies. 



As to the Elint of the district, the railway-cuttings between P6rigueux and 

 Thenon show abundance of flint-nodules in the Cretaceous limestone ; flint also 

 abounds in the limestone near Montignac; and probably these are the same 

 flint-bearing beds, as the general strike, or bearing, of the strata passes through 

 the two localities. 



The Cretaceous system is represented in the Department of the Dordogne by 



* ' Stat. geologique &c. de la Meuse,' p. 12, pi. 10. figs. 9-11. 



