Vol. 62.] TARNS OF THE CANTON" TICINO. 185 



Lago di Lucendro (see Pis. XIV, XV, & XXI).— This lake 

 lies at a height of 6832 feet above sea-level, in the valley between 

 the Piz Lucendro and the valley of the Gotthard Reuss, above 

 Hospenthal. In shape, it is roughly a parallelogram, with the 

 longer diameter running north-east and south-west. The greatest 

 length from east to west is rather more than 765 yards ; and the 

 greatest width is 306' yards, the average width being about 270 

 yards. The water is, to a slight extent, retained by the supports 

 of the bridge at the exit. The greatest depth met with was 

 126 feet ; and the axis of greatest depth, as shown in the bathy- 

 metrical chart (PI. XXI), lies parallel to the length of the lake, and 

 rather nearer the western than the eastern bank. The prolongation 

 of the contours along this line, into the bay at the western end, is 

 an interesting feature of the chart. The valley in which the lake 

 occurs is occupied at its upper end by the Lucendro Glacier. 

 The drainage of this glacier is carried off by three streams, which 

 form the source of the Eeuss and constitute the chief feeders 

 of the lake. This also receives the overflow from the little lake to 

 the north-west, situated at the eastern base of the Piz del Uoino, 

 and several streams which drain the cirque-like wall on the south 

 and west of the lake. The lake occupies a rock-basin, and lies 

 along the junction of the Pibbia gneiss and the biotite-schist, the 

 latter occupying the northern bank. A good section of the schist is 

 seen along the north side of the lake, about 500 yards from the 

 bridge. Here the schist is much crushed and contorted, and 

 penetrated by veins of granite. If the veins are offshoots of the 

 Pibbia gneiss, the lake must lie absolutely along the junction of 

 the two rocks : as in most other cases, however, the actual shore- 

 line is modified by scree and delta-material. 



With regard to the origin of this lake, there is no evidence of 

 solution having played any part in its formation. On the other 

 hand, the promontory of solid rock jutting out into the lake from 

 the exit does not seem consistent with excavation by ice, as usually 

 understood ; and the presence of this lake along the junction of a 

 massive granitic gneiss and a mica-schist points undoubtedly to the 

 conclusion that here again the main determining factor for the 

 existence of the lake has been the occurrence of a line of weakness 

 along the contact between a hard and a comparatively-soft rock, 

 giving rise to differential weathering. The whole district, however, 

 has been intensely glaciated, and a prolongation of the Lucendro 

 Glacier must formerly have passed over the site of the lake. It is 

 quite possible that this glacier removed the weathered surface of 

 the disintegrated schist, while it made but slight impression on the 

 harder granite. The uneven surface thus produced would cause 

 the accumulation of water, so soon as the glacier withdrew from the 

 lower part of the valley. 



The origin of Lago Orsirora and Lago Orsino, on the north of 

 Lago di Lucendro, appears to be due to the same cause, as they lie 

 along the junction of the gneiss on the south and the granulite on 



