INTERGLACIAL EPOCHS. 305 



of the plants is still incomplete, but the following have been 

 recognised by Sig. Sordelli : — ■ 



Magnolia, Sp. 



Acer pseudo-platanas, L., var. paucidentata, Sand. 



Buxus sempervirens, L. 



Ulmus campestris, L. 



Taxus baccata, L. 



Phacidium buxi, Westdp. (parasitic on the leaves of the box). 



Above this highly fossiliferous marl come massive accumula- 

 tions of morainic detritus with large erratics. The complete 

 section at Pianico is thus in descending series as follows : — 



1. Glacial morainic deposits. 



2. Lacustrine marl with Rh. hemitcechus, etc. 



3. Clay passing down into silt and sand, which contain 



scattered and sporadic stones. 



4. Sand, etc., abundantly charged with glaciated stones. 



At what was formerly the head of the ancient lake the 

 river has exposed a seam of impure lignite, intercalated among 

 deposits of silt and sand. 



Stopanni has demonstrated that this ancient lake owed its 

 origin to the damming up of the gorge of Castro, through which 

 the river Borlezza makes its way into Lake Iseo. The height 

 to which the mountain-slopes are glaciated, and the elevation 

 reached by the lateral moraine of the glacier that dammed the 

 valley, show that the icy bar rose to a level of more than 300 

 feet above the present surface of the lacustrine deposits of the 

 Val Borlezza. Enormous quantities of morainic debris were 

 toppled over the side of the glacier into the lake of the Val 

 Borlezza, while quantities of striated stones, along with sand 

 and mud, were extruded upon the bed of the lake from the 

 bottom of the glacier. At this time the stream flowing into the 

 old lake of Borlezza was swelled by muddy torrents escaping 

 from the ancient glacier of the Val Seriana, which then occupied 

 the basin of Clusone, and thus the bed of the lake came in time 

 to be covered with layers of mud and silt and sand, which 

 gradually attained a thickness of several hundred feet. While 



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