OE THE OUTER HEBRIDES. 847 



from the south-east. We see this shown, in the first place, by the 

 distribution of the deposit. It does not occur along the rocky east 

 coast, but comes on in force behind the ridge of Beinn Ebhal and 

 Beinn Li ; and it tends to gather most continuously over low-lying 

 and gently inclined ground, where there were no obstacles to the 

 overflow of the ice from the Minch. Excellent illustrations of these 

 phenomena occur in the neighbourhood of Loch Maddy. Thus 

 immediately behind the ridge of high ground that forms the eastern 

 boundary of the loch thick till is seen sloping down to the sea. 

 Till likewise occurs in similar sheltered places on the northern 

 shores of Loch Maddy, as along the eastern margin of Loch Partan 

 Channel. Again it may be seen on some of the flat islets in the 

 loch, such as Elodeidh and Hamarseidh ; and here and there also 

 along the shores of Loch Theoravagh good sections are obtained. It 

 does not occur upon the rough ground facing the Minch, simply 

 because over that area excessive grinding action necessarily pre- 

 vented its accumulation ; it gathers thick in the rear of the east- 

 coast ridge because there it experienced some shelter, and it spreads 

 out thinly over the wide low grounds of the interior because in that 

 region the ice, meeting with no obstructions, probably flowed with a 

 smooth, equal, and somewhat slower motion. 



The direction taken by the ice is yet further shown hj the rude 

 arrangement of stones and boulders in those deposits of till that 

 occupy the lee-side of prominent rocks. This may be seen in many 

 of the openings made on the sides of the roads throughout the 

 island ; but as the phenomena are precisely the same as those men- 

 tioned in connexion with the till of Harris, they need not be further 

 described. 



Lastly, the trend of the old rner de glace is marked out by the 

 boulders which have been pushed from Beinn Ebhal and Beinn Li 

 westwards into the interior. In the till of the central low grounds 

 occur many boulders of various peculiar rocks which are found in 

 situ in the east-coast ridge, but not in the interior. Conspicuous 

 among these are a dark blackish-green hornblende-rock and horn- 

 blende-schist, and various slaty and schistose rocks. Another well- 

 marked stone which is of frequent occurrence in the till is a dark 

 greenish felspathic and hornblendic rock, thickly set on weathered 

 faces with points of a hard pink- coloured mineral which I could not 

 at the time determine, and the specimen I brought away has un- 

 fortunately been lost. Macculloch refers to this rock as being 

 exposed upon the east coast, where, according to him, it is " thickly 

 strewed with prominent points, the crystals of a harder matter 

 which has resisted corrosion," from which, perhaps, it may be 

 inferred that he was equally unable to determine what the hard 

 pinkish mineral was. Boulders of a granatiferous gneiss, which 

 have probably come from the same quarter, are associated in the till 

 with the varieties just mentioned. 



5. Erratics. — Comparatively few angular erratics are scattered 

 over North Uist. Nearly all those we saw were either enclosed in 

 the till, or had probably at one time been so. They were for the 



