30 4 PREHISTORIC EUROPE. 



of the Val Borlezza, and, passing west and south-west by the 

 Valle Cavallina, descended as far as the village of Entratico on 

 the banks of the river Cherio, a few miles above Trescorre. At 

 the foot of the lake the main glacier was divided by the Colle 

 d'Adro, the largest mass flowing south between Iseo and Clusone 

 towards the Colline della Francia Corta, and the shortest and 

 narrowest limb extending west by Sarnico down the present 

 course of the Oglio as far as Calepio. Several of the little lateral 

 valleys which drain into Lake Iseo do not appear to have sup- 

 ported glaciers of their own, but were simply dammed up by 

 the great glacier of the Valle Camonica as it flowed past them 

 on its way towards the plains. This was the case with the 

 Val Borlezza, which now opens upon the lake at the gorge of 

 Castro, not far from the head of the lake ; and the smaller 

 valleys of Adrara and Forestro, near Sarnico, at the foot of the 

 lake, are examples of the same phenomenon. The valleys referred 

 to were thus converted into lakes, upon the beds of which 

 quantities of mud and loam were deposited. While the great 

 glacier was melting away the lakes in these side valleys were 

 drained, and the streams, resuming their work of erosion, 

 eventually cut their way down to the bottom of the old 

 lacustrine sediments, which are thus exposed to us in fine 

 sections. One can see at a glance that the Val Borlezza is only 

 the bed of a dried-up lake, now deeply incised by the stream 

 which has dug its way down to a depth of more than 200 feet 

 from the surface to join the Lago d'Iseo. In the sections dis- 

 closed by the stream below Pianico the lacustrine strata, con- 

 sisting of silt, clay, and sand, in horizontal layers, are underlaid 

 by morainic deposits charged with many glaciated and striated 

 stones. At Pianico the lacustrine clay and sand are overlaid 

 by a mass of white marl — a kind of calcareous tripoli, as 

 Stopanni describes it, — abundantly charged with the limy 

 skeletons of microscopic organisms. This deposit has yielded 

 abundant remains of plants and fish, together with those of a 

 rhinoceros (JR. hemito&chus, Falc), determined by Dr. Forsyth 

 Major. The fish have not yet been studied, and our knowledge 



