112 Proceedings of Royal Society of Edinburgh. [sess. 
The bottom of Loch Builg is divided into three basins, the more 
important one being in the middle of the loch. These basins are 
separated by two ridges, as shown on the sketch map. These 
shallowings might be caused by moraines on the floor of the lake, 
which seems to us a better explanation than to suppose that these 
basins are separated by rocky barriers ; it is impossible, however, 
to give a definite opinion on this point. When sounding, we 
found along the western shore a submerged talus one foot below 
the water level, about 12 feet broad, with a steep slope falling 
suddenly to 12 feet. Have we here an ordinary talus at the foot 
of a slope, or a submerged moraine ? It is impossible to say ; 
anyhow, the fact is worthy of record. 
Note on Two Rock Basins in the Alps. By Dr Leon W. 
Collet, F. Swiss Geol. S., Assist, to Sir John Murray, K.C.B. 
True rock basins are not rare at the head of many small mountain 
valleys or corries of France and Switzerland. Many flat alluvial 
plains above gorges in Switzerland, as well as in the Highlands of 
Scotland, were without doubt at one time glen lakes, as they are 
called by Sir Archibald Geikie, or true rock basins which have been 
filled up by the sand and the mud brought into them by their 
tributary streams. 
I propose in this short note to describe two of these interesting 
rock basins situated at an elevation of about 5500 feet on the 
mountains called by Swiss geologists “ Hautes Alpes Calcaires ” 
(high calcareous Alps). 
1. Plain of Barberine.* 
The plain of Barberine, as shown in fig. 3, is an alluvial one, 
crossed in its length by a stream ; its cross-section is U-shaped. 
At the lower part of the plain the stream enters a gorge with steep 
slopes, i.e. with a V-shaped cross-section. The plain is an old 
true rock basin, which has been eroded by the glacier coming from 
the peaks above (where there are still hanging glaciers), and has 
* For the geological map of the region, see L. W. Collet, Mat, Carte Geol, 
Suisse , liv. xix., nouv. serie, 1904. 
