LAKES IN RELATION TO GEOLOGICAL FEATURES 489 
height of the Craig an Tairbh pass, where the rocks still retain the 
potholes eroded by the old glacial stream. The continued 
recession of the ice was slow enough to allow a terrace of beach 
and delta material to accumulate along the ice-dammed lake. 
Subsequently, when the Pass of Brander was free from ice, the lake 
assumed a form approaching the present outlines. Since glacial 
time the upper part of the northerly rock-basin has been much silted 
up with the alluvia of the converging streams, and small delta lakes 
are being formed by the advancing sediment. The contours at the 
upper end of the loch show that the slope there is that of an 
advancing delta. 
Awe (Inver basin). — Shallow basin ponded by drift with morainic debris 
on Cambrian quartzite and Olenellus beds. 
Ba (Mull), — A valley rock-basin in granophyre, intrusive into igneous 
rocks of the Tertiary volcanic plateau in Mull. The lines of fissure 
followed by the great series of basalt dykes which traverse the 
plateau, seem to have determined the direction of the valley, and 
consequently the trend of the lake. Its water-level is raised by a 
dam consisting of raised-beach material. 
Ba (Tay basin). — Shallow, drift-dammed loch lying on moraine-strewn 
surface of the granite mass of Rannoch Moor, the moraines forming 
numerous islands and headlands. 
Bad a' Chrotha. — Rock-basin in Torridon Sandstone nearly silted up. 
Bad a' Ghaill.— Vol. H. Part L p. 190. 
Bad an Sgalaig. — Rock-basin in Lewisian Gneiss. 
Baddanloch. — Drift-dammed shallow loch in wide valley carved out 
of granulitic quartz-biotite schists and muscovite-biotite gneiss 
and granite veins. 
Baile a' Ghobhainn. — Rock-basin in limestone and black schist due 
partly to ice action and partly to solution. The limestone overlies 
the black schist or slate, which acts as the retentive layer and forms 
the bed of the loch along the line of an eroded anticline ; the surface 
of the water determining the line of saturation of the limestone 
which occupies the synclinal folds (see Loch Fiart). 
Balgavies. — Lake ponded by drift upon Lower Old Red Sandstone strata. 
Beag. — Part of the same valley rock-basin as Loch Clunie. 
Beannach (Gruinard basin). — ^Fills hollows among moraines resting on 
Lewisian Gneiss. 
Beannach (Inver basin). — Rock-basin in Lewisian Gneiss, so called from 
the numerous islands (roches moutonnees) with which it is studded. 
Beannachan.— Vol. II. Part I. p. 289- 
Beinn a' Mheadhoin. — Valley rock-basin connected with Loch an Laghair. 
Beinne Baine, na. — Lake lying partly in crystalline schist and partly in 
drift, situated on watershed. 
Beiste, na.— Small hollow in boulder clay resting on Torridon Sandstone. 
Beithe, na. — Kettle-hole in 100-ft. raised beach. 
