INTERGLACIAL EPOCHS. 



3ii 



gravel-deposits indeed present the appearance of having been 

 spread over the bottom of the valley by torrential streams flow- 

 ing chiefly from the mountain -valleys above Gandino (Val 

 Tuona, Val Concosola, and Yal Piana), swelled by streams coming 

 from the hills behind Peja and Leffe. 



These appearances, and others which will presently be 

 described, lead me to conclude that the conglomerate belongs to 

 a period long subsequent to the silting-up of the lake. In the 

 pits at Leffe its junction with the underlying lignite-beds is 

 well exposed, and the latter are there seen to have been much 

 denuded before they became buried under the tumultuous 

 shingle that overlies them. There is no dovetailing or inter- 

 osculation of fine and coarse sediment, such as we might have 

 expected to find had the lake been gradually filled up in the 

 manner supposed by Stopanni ; but the lacustrine beds are 

 abruptly separated by a clearly-defined line of demarcation from 

 the coarse deposits above. The annexed sketch -section will 

 exhibit the general features referred to. Here, it will be 

 observed, a mass of coarse gravel and shingle, horizontally 



Fig. 9. — Section of Lignite, etc., Leffe, near Gandino. 

 1, Lignite ; 2, Silt, clay, etc. ; 3, Shingle. 



bedded, or approximately so, and reachiDg a thickness of 30 to 

 50 feet, lies directly upon the truncated edges of the lacustrine 

 deposits. The lower portions of the conglomerate-beds contain 

 lines of sand, with fragments of lignite, evidently derived from 

 the denudation of the underlying strata. The conclusions I 



