16 James Croll — Transport of Wastdale Crag Blocks. 



transported by land-ice. The agency of floating ice under some 

 form or otlier is assvimed by tbem all. 



We bave in Scotland phenomena of an exactly similar nature. 

 The summits of the Ochils, the Pentlands, and other mountain 

 ranges in the east of Scotland, at elevations of from 1,500 to 2,000 

 feet, are not only ice-marked, but are strewn over with boulders 

 derived from rocks to the west and north-west. Many of them 

 must have come from the Highlands distant some 50 or 60 miles. 

 It is impossible that these stones could have been transported, or 

 the summits of the hills striated, by means of ordinary glaciers. 

 Neither can the phenomena be attributed to the agency of icebergs 

 carried along by currents. For we would require to assume not 

 merely a submergence of the land to the extent of 2,000 feet or so, — 

 an assumption which might be permitted, — but we should have to 

 assume that the currents bearing the icebergs took their rise in the 

 elevated mountains of the Highlands, a most unlikely place, and 

 that these currents radiated in all directions from that place as 

 a centre. 



In short the glacial phenomena of Scotland is wholly inexplicable 

 upon any other theory than that, during at least a part of the 

 glacial epoch, the entire island from sea to sea was covered with one 

 continuous mass of ice of not less than 2,000 feet in thickness. 



In my paper on the Boulder-clay of Caithness,^ I have shown 

 that if the ice was 2,000 feet or so in thickness, it must, in its motion 

 seawards, have followed the paths indicated by the curved lines in 

 the diagram accompanying that paper. In so far as Scotland is 

 concerned, these lines represent pretty accurately not only the paths 

 actually taken by the boulders, but also the general direction of the 

 ice-markings on all the elevated mountain ridges. But if Scotland 

 was covered to such an extent with ice, it is not at all probable that 

 Westmoreland and the other mountainous districts of the North of 

 England would have escaped being enveloped in a somewhat similar 

 manner. But if we admit the supposition of a continuous mass of 

 ice covering the North of England, all our difficulties regarding 

 the transport of the Wastdale blocks across the Pennine chain dis- 

 appear. An inspection of the diagram above referred to will show 

 that these blocks followed the paths which they ought to have done 

 upon the supposition that they were conveyed by continental ice. 



That Wastdale Crag itself suffered abrasion by ice moving over it, 

 in the direction indicated by the lines in the diagram, is obvious 

 from what has been recorded by Dr. Nicholson and Mr. Mackintosh. 

 They both found the Crag itself beautifully moutonneed up to its 

 summit, and striated in a W.S.W. and E.N.E. direction. Mr. 

 Mackintosh states that these scorings run obliquely up the sloping 

 face of the crag. Ice scratches crossing valleys and running up the 

 sloping faces of hills and over their summits are the sure marks of 

 continental ice, which meet the eye everywhere in Scotland. Dr. 

 Nicholson found in the drift covering the lower part of the Crag, 

 pebbles of the Coniston flags and grits from the west.'^ 



^ Geological Magazine for May and June, 1870. 

 2 Trans. Edin. Geol. See, vol. i., p. 136. 



