834 J. GEIKIE ON THE GLACIAL PHENOMENA 



glacial looks as perfect as if the Ice Age had but recently passed 

 away. But although the dome-shaped rocks have so fresh an 

 appearance, striated faces do not frequently occur. The roehes 

 moutonnees are all more or less weathered, and the fine marks left 

 by the ice-plough have often been entirely obliterated. Now and 

 again, however, on bosses of more durable varieties of gneiss, striae 

 may be detected. We found a number to the east of Loch Langa- 

 bhat, which varied in direction from W. 35° N". to W. 40° N. Be- 

 tween Loch Langhabhat and Cnoc a Ghobha the hills are smoothly 

 rounded and pretty well clothed with grass, recalling the green 

 slopes of the Silurian Uplands of Peeblesshire. "We got no strise 

 on these hills, but at their base, on exposed rocks about half a mile 

 from Loch Langabhat, found them pointing W. 35° 1ST. On the hills 

 overlooking Loch na Morcha from the east, a number of striated 

 rocks are seen, the direction of glaciation varying from W. 30° IN". 

 to W. 35° JST. The same trend is found upon the rocks in the 

 vicinity of Obbe and on the seaward slopes of Straundabhal in the 

 district of Eodal. 



All the mountains of Harris are fluted on the large scale, the 

 rounded ridges and intervening hollows running in the direction of 

 the strike of the gneiss, and being most conspicuous when the latter 

 coincides with the trend of glaciation. This fluted appearance is 

 perhaps most noticeable on hill-slopes that face an open valley or 

 a sound of the sea. Thus along both shores of West Loch Tarbert 

 it is well seen. The mountains that rise south and north of the 

 river Lacasdail are also well fluted ; and an excellent example of the 

 same phenomenon is afforded by the hills that face the Sound of 

 Harris between Kudh-Reinis and Eudh-Charnain. This fluting is 

 evidently due to the unequal yielding of the gneissic strata ; and al- 

 though its origin probably dates back to preglacial times, there 

 can be no doubt that much of it is due to glaciation ; for it is when 

 the line of strike corresponds with the trend of the ice-flow that the 

 fluting is most marked. When the strike and the glaciation do not 

 so agree in direction the fluting becomes less obvious, and often 

 wholly disappears. 



We did not land upon any of the islets in East Loch Tarbert, but 

 we touched at Scalpa twice, and had a good opportunity of seeing its 

 configuration" and that of the other islets in its vicinity. It has 

 clearly been glaciated all over, and the same has been the case with 

 Taranseidh and Scarpa off the west coast of Harris. 



In fine, the glaciation of Harris is so clearly marked that no fur- 

 ther evidence of till or erratics ' is needed to show that the whole 

 land has been abraded by glacier-ice coming from the south-east. 

 Even the highest mountains, as we have seen, have been striated 

 horizontally along their flanks by ice that streamed against them on 

 its way out to the Atlantic. As one might have expected, the strise 

 are frequently deflected ; for the bottom of the ice-stream would 

 naturally accommodate itself to the surface over which it flowed. 

 Such local deflections, however, were not propagated to the upper 

 strata of the ice, as is shown by the persistent direction of the stria? 



