268 DR, J. W. GREGORY ON THE WALDENSIAN [May 1 894, 



but in the Maritime Alps representatives of all the principal systems, 

 from the Carboniferous upwards, occur on both flanks of the main 

 chain. Traced north from the Apennines and the Maritimes, the 

 Carboniferous beds can be followed with some interruptions along 

 the western slope, through Briangon to the base of Mont Thabor. 

 Of the age of these beds there can be no question ; they have been 

 described by Fournet, Lory, Zaccagna, and more recently by Kilian : 

 they are not very fossiliferous, but the plants recorded l from 

 Monestier de Briangon, Puy St. Pierre, Chardonnet, Col de Buffer, 

 etc., are sufficient to precisely fix their age. The Carboniferous is 

 overlain by a series of rocks described by Zaccagna as Permian, 

 which are doubtless a portion of the Poikilitic series ; these beds in 

 several places distinctly overlap the Carboniferous and unconform- 

 able overlie the calc-schists. Thus, in Zaccagna's section from 

 St. Paul across the Monviso to Eocca Cavour, the Carboniferous beds 

 are not included, but Pointe de Mary is capped by Permian beds, 

 resting u neon form ably on the calc-schists. The basal conglomerates 

 of the Permo-Triassic series overlie the schists and contain numerous 

 fragments both of them and of the igneous rocks with which they are 

 associated. The Carboniferous rocks, however, are in no place 

 found in superposition to the schists, nor are fragments of the latter 

 met with in the former; Kilian has, therefore, suggested the view 

 that the schists are probably of Carboniferous age and represent 

 the altered eastward continuation of these. He says " le terrain 

 houiller disparait a. Test dune ligne Modane-Briancon-Saint-Paul, et 

 sembh cider la place aux schistes lustres." 2 



This view has been strongly opposed by Bonney and Zaccagna, 

 who agree in assigning the whole of the schists to the x^re- 

 Palaeozoic. Prof. Bonney has given 3 a section across the pass of 

 Mont Genevre and the Col de Sestrieres, in which he limits the 

 Mesozoic series to the upper part of Monte Chaberton, including in 

 the Archaean the whole of the base of the mountain below the level 

 of the Italian forts on the road from Cesana to Clavieres, and all 

 the hills on the east side of the Dora Valley. 



During the present year, however, the search for radiolaria which 

 has been stimulated by the remarkable results obtained by Issel, 

 Parona, and Pantanelli in Liguria, has been rewarded by a discovery 

 by Prof. Parona which has thrown an entirely new light on the 

 whole question. This is no less than the occurrence of a radiolarian 

 schist, or ' phthanite,' or cleaved radiolarian mud included in the 

 calc-schist series. Prof. Parona * has described the stratigraphical 

 relations of this rock, which occurs interbedded in some green and 



1 Lory, Bull. Soc. Stat. Isere, ser. 2, vol. vii. (1864) pp. 26, 27. 



2 W. Julian, 'Notes sur l'Histoire et la Structure geologique des Chaines 

 alpines de la Maurienne, du Brianc/ninais et des Regions adjacentes,' Bull. 

 Soc. geol. France, ser. 3, vol. xix. (1891) p. 580. 



3 yuart. Journ. Geol. Soc. vol. slv. (1889) p. 80. 



4 C. F. Parona, ' Sugli Schisti ulicei e radiolarii di Cesana, presso il Mon- 

 giaevra,' Atti R. Accad. Sci. Torino, vol. xxvii. (1892) pp. 306-318. 



