LAKES IN EELATION TO GEOLOGICAL FEATURES 513 
The Caithness flagstones floor a large area of the loch along its 
• northern shore. 
Wester. — Partly in boulder clay, and ponded by blown sand. The sea 
sometimes enters the loch during exceptionally high tides. 
Whinyeon. — Rock-basin in Silurian greywackes and shales. 
White (Ryan basin). — Kettle-hole in fluvio-glacial deposits cut off from 
the Black Loch by the delta of Sheuchan Burn. 
White of Myrton (Luce basin). — Ponded by drift. 
Whitefield. — Ponded by drift. 
WooDHALL. — Partly a rock-basin across the strike of Silurian greywackes 
and shaleS;, and partly in drift. 
MAPS 
Plate XVI., p. 448. Geological Map of Scotland, giving the broad distribution of 
the rock-groups, and illustrating the geological section of this paper. The 
Lewisian Gneiss of the North- W est Highlands is distinguished from the 
metamorphic strata lying between the Moine thrust-plane and the fault 
along the eastern border of the Highlands. Each of the palaeozoic systems, 
excluding the Permian, is shown by one colour. The Permian and 
mesozoic strata are together indicated by one colour. The contemporaneous 
and intrusive igneous rocks of Tertiary time are differently expressed from 
those of palaeozoic age and older date. The important disruptions giving 
rise to shatter-belts are defined by thick black lines. 
Plate XVII., p. 464. Orographical and Bathymetrical Map of Scotland, showing 
the relief of the land surface and the depth of the surrounding sea. It is 
introduced for the purpose of comparison with the geological map, to show 
the relation between the geological structure and the development of the 
surface contours. 
Plate XVIII., p. 474. Map showing Direction of Ice-flow and Probable Ice-front 
in North-West Europe during Maximum Glaciation. It indicates the main 
centres of ice-dispersion in Scotland during the climax of glacial conditions, 
the union of the local ice-sheets with that of Scandinavia, the probable path 
of the combined ice-field across the Continental Shelf, and the conjectural 
ice-front along the Atlantic and Arctic Rise. 
33 
