Page:Quarterly Journal of the Geological Society of London, vol. 29.djvu/273

 map, the lower marks trend S.W., and avoid the mountains where they are not the marks of local glaciers born amongst the high glens, and high hills.

XIII. The United Systems of Great Britain and Ireland. — I now believe that Ireland was, like Greenland, entirely covered, that it became, like Iceland, partially uncovered, and then, like Scandinavia, nearly bare. But I cannot believe that Ireland ever was a patch of land covered by an equal area of thick ice bounded by the sea. During its Greenland period the Irish system must have been united to Scotland. Having got to Red Bay in Antrim I took a cast northwards by Fairhead to see what I could find there. As I have said, the Antrim hills are made of basalt and trap and chalk ; and Antrim drift generally is made of Antrim rocks. At Cushendal are many great blocks of grey mica-schist ; and these are strewn over the northern end of the Antrim hills, together with other stones which commonly occur in " Northern Drift." Along the sea-coast are steep grounds along which the road runs uphill and down. Some of the rocks hereabouts are metamorphic, with veins and dykes of granite in them ; but I could find nothing in situ like the large grey erratics. Along this coast striae run horizontally, and point at the sea-horizon north of the Mull of Ceantire, and towards the glen at the foot of Slieve Mish, which leads S.W. towards Galway Bay. Near the Preventive Station the hill-tops are white chalk, bare, or barely covered by fine green turf. There, and at Fairhead, up to heights of 850 and 1100 feet above the sea, numerous large erratics of the same heavy hard grey mica-schist rest conspicuous upon the hill- tops. At some places the builders of stone circles have gathered the largest blocks to crown the highest top, while smaller blocks are scattered where they fell. Along this ridge to the cliff at Fairhead these great erratics are strewn over the chalk. Produce lines ruled upon the hill-sides about Fairhead, upon a map, and they pass near Loch Killesport in Argyllshire. There, near Ormsary, is the largest erratic which I have seen in the British Isles. Thence glacial strias cross the water-shed into Loch Fyne, and run up Loch-Fyne side-, past Inveraray, where all the hills are glaciated till they lead up to hills near Tigh an Dromma, about Loch Awe, Loch Lomond, Glen- falloch, Glen Dochart, &c. in the Perthshire highlands. But rocks and erratics in Ceantire, in Cowal, and about the central highlands of Scotland, cannot be distinguished from the erratics upon the chalk hills at Fairhead in Antrim.

XIV. Maps. — If a man could grow on the scale of a mile to the inch, he could see all Scotland at a glance. The ordnance survey of Scotland, drawn on the scale of an inch to a mile, has now advanced so far that four sheets joined give common men a giant's view of the low country between the Forth and Clyde, with parts of the highlands to the north and south.

Looking down upon this miniature country as a giant seventy miles high might look upon Scotland, we can see that it is crossed diagonally by a big groove with a broken ridge in the middle of it. After sun-down on a fine clear cold evening, November 13, 1872, I