Vol. 62.] TARNS OF THE CANTON TICINO. 191 



EXPLANATION OF PLATES VII-XXI. 



Plate VII (facing p. 168). 

 Map of the Piora Lakes, on the scale of 1 : 42,240. 



Plate VIII. 



View of Lago Ritom, looking east from the exit of the lake. It shows the 

 contrast between the dip-slope of the gneiss on the southern shore, with its 

 bays and headlands, and the escarpment of calc-mica and black-garnet schists 

 forming the northern shore, down which cascade the three waterfalls from Lago 

 Tom, Lago Cadagno, and the Val Piora respectively, counting from left to right, 

 and terminating at the edge of the lake in their respective deltas. Pizzo Taneda 

 forms the highest point along the skyline ; while immediately to the left lies the 

 col over to Lago Scuro, from which the photograph (reproduced in PI. X) was 

 taken. Below this, again, the notch in the middle distance marks a portion of 

 the old Foos valley. On the skyline to the right of Pizzo Taneda is seen the gap 

 occupied by Lago Taneda, the overflow from which can be discerned falling 

 over the precipice of actinolite-schist into the Lago Cadagno, which lies 

 immediately below. The Val Piora is situated on the extreme right of the 

 photograph, behind the middle-distance escarpment, while Lago di Murina'scio 

 occupies the cirque above it. 



Plate IX. 



View of Lago Tom, looking towards the barrier of rauchwacke at the lower 

 end, in which the water-channel leading into the rock is seen. The delta 

 on the extreme right forms the upper end of the lake. The rauchwacke is 

 seen occupying the centre of the picture. The skyline is composed of dip- 

 slopes and escarpments, on the right and left respectively of each of the hills. 



Plate X. 



View taken from the col to the west of Pizzo Taneda (shown in PI. VIII), 

 looking across Lago Tom and the western end of Lago Ritom to the Val 

 Levantina. The observer is looking straight down the old valley of La Foos, 

 sections of which can still be seen below Lago Tom and at the exit of Lago 

 Ritom. The distant range forms the watershed between the Val Levantina and 

 the Val Maggia, and, although not visible. Lago Tremorgio lies on the flank of 

 this range on the extreme left. The snow-filled lake in the foreground is 

 scree-dammed, and lies on a ledge of actinolite-garnet-schist 1000 feet above 

 Lago Tom. 



Plate XI. 



Panoramic view from the watershed between Lago Tom and Lago Cadagno, 

 looking east. Lago Cadagno lies in the foreground on the left, and the gap 

 immediately above it is occupied by Lago di Murinascio ; while the delta at the 

 head of Lago Ritom lies below on the right. The stream running into this 

 down the wooded slope marks the isolated outcrop of rauchwacke at the eastern 

 end of the lake. Up the centre of the picture runs the Val Piora, cut in the 

 outcrop of the main mass of rauchwacke. Starting in the Pizzo Columbe (which 

 forms the central peak in the skyline), this runs through Lago Cadagno, through 

 the point from which the photograph was taken to Lago Tom, and away to the 

 Val Canaria. The cattle-sheds in the foreground are built on the screes which 

 dam the western end of the lake ; while behind them, the moraine is seen forming 

 its southern shore. The dip-slopes and scarp-faces formed by the actinolite- 

 schists are well seen on the left in the middle distance ; while the gorges, 

 through which the rivers from Lago Cadagno and the Val Piora fall into the 

 Lago-Ritom basin, are conspicuous in the foreground. 



Plate XII. 



Fig. 1 is a view of the barrier of rauchwacke at the lower end of Lago Tom. 

 It shows the spring issuing from the rauchwacke at its junction with the 



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