SIR HENRY H. HOWORTH, J).C.L., F.R.S.^ ON ICE OR WATER. 225 



side, showing that the hill was no eftectual impediment to the 

 ice-movement. 



The second example is taken from the Firth of Clyde. Those 

 who know this part of Scotland will recollect that the Valley 

 of Loch Long enters the Clyde opposite Greenock in a direction 

 at right angles to that of the latter. A glacier descended from 

 the Argyllshire highlands through Loch Long into the firth of 

 Clyde, which is very deep at this part of its course, and on the 

 south side of the Firth the ground rises out of the water into 

 considerable hills. These are formed of basaltic rock, mammi- 

 lated and striated with glacial markings. But the remarkable 

 fact is that the stride point in the direction of the Loch Long 

 Valley — not in that of the Clyde; in other words, approximately 

 north, not westward, which is the direction of the banks of the 

 Clyde at this place. It is clear, therefore, that the glacier, 

 coming down from the north, passed right across the Ch'de 

 V)asin and ascended the hio;h ^.round formino- the southern bank. 

 The evidence is perfectly clear in this case* that the ice 

 ascended the ridge opposed to its course. 



My last instance will be taken from Ireland, of which a 

 glacial map will be found in my httle work The Physical 

 Geology of Ir eland. '\ This map does not support the view that 

 " a glacier cannot travel over enormous stretches of country," 

 as it shows that the whole of the central plain of Ireland was 

 covered by an ice sheet moving along lines in a southerly 

 direction and originating in an axis running along the borders of 

 LTlster. Now here we have (at least) one remarkable example 

 of the power of glacier ice to ascend and pass over obstructions 

 to its course and to travel over large stretches of country. 



Again ; standing on Bray Head, about 900 feet above the 

 sea, and 200 feet above the plain, and formed of Cambrian grits 

 and slates, we observe that the rocks are finely glaciated and 

 striated by lines pointing in (approximately) a north-west 

 direction, that is to say, over the plain, formed of carboniferous 

 limestone which stretches away at a depth of several hundred 

 feet beneath our feet. In other words, the ice, moving over the 

 plain from the north-west (the position of the central axis of 

 movement), has ascended the slopes of Bray Head and passed 

 over the summit in the direction of the sea. When I first 

 observed these phenomena I was, I confess, struck with amaze- 



* The glacial striie at this place were marked by myself on the 6-inch 

 map Ts hen I was carrying out the Geological Survey in 1870. 

 t 2nd edition 1891 . 



