262 M. A. Giiyot on the Distribution of Hocks 



throughout the Avhole extent of the plain of Gex and Geneva, 

 but they are sporadical, mixed, and no longer in the zone of 

 the large blocks like that we have just descinbed. 



In this girdle of the large blocks of the Jura, it is the 

 varieties which must have issued from the valley of Trient 

 which predominate. Those of the Yal Ferret are rarer, 

 and are found rather below the two zones towards the plain. 

 This arrangement, and the fact that the lower limit of the 

 zone of blocks is distinctly defined, even in the midst of the 

 forests and uncultivated rocky places, prevents us ascribing, 

 as has been done, the absence of the large blocks in the 

 plain solely to the hand of man and the progress of cultiva- 

 tion. 



The granites of Haut Valais, or those on the right flank 

 of the valley, occupy a very secondary place in the plain. 

 Pretty numerous in the Valais on the right bank of the Rhone, 

 in the plain they are superseded by the pudding-stones of 

 Valorsine towards the interior of the basin. They follow a 

 curved line which passes along the Jorat between Lausanne 

 and Vevey, turn slowly to the east on the plateaux Avhich 

 surround Moudon, then follow the heights to the north of 

 Romont, and rejoin the Alps of Fribourg at tlie foot of La 

 Barra. The greater part of the granites Avhich are scattered 

 in small numbers to the north of this line, as far as the neigh- 

 bourhood of Neuchatel, Fribourg, and Berne, seem to have 

 this origin. 



On the other hand, I think I may rank in this class a con- 

 siderable number of granite blocks, met with on the plateaux 

 which overlook Morges, near the village of Bussy, and as far 

 as Aubonne and the plains of Biere. These blocks might 

 form a second zone running from the east to the west on the 

 heights of Jorat, parallel to the banks of the lake, as if to re- 

 join the Jura. 



The pudding-stones of Valorsine, along with the red or wine 

 coloured conglomerates, have a more distinct domain than any 

 other rock. They occupy by themselves the right side of the 

 basin, from the mouth of the valley of the Rhone, and cover 

 the plateau of Jorat, as far as the environs of Lausanne. The 

 red conglomerates keep almost exclusively at the upper limit 



