THE ICE AGE AND ITS WORK. 787 



far above the native rock. Thus, bowlders of the peculiar Fox- 

 dale granite are found about fourteen hundred feet higher than 

 the highest point where there is an outcrop of this rock. 



The Scotch ice-sheet flowed outward on all sides, but on the 

 east it was met by the southward extension of the great Scandi- 

 navian ice-sheet. On the extreme north the meeting of these two 

 ice-sheets resulted in a flow to the northwest which glaciated the 

 Orkney Islands, while the Shetlands, much farther north, received 

 the full impact of the Scandinavian ice alone, and are therefore 

 glaciated from the northeast. The dividing line of the Scotch and 

 Scandinavian ice-sheets was in the North Sea, not far from the 

 east coast of Scotland ; but farther south, at Flamborough Head 

 and Holderness, the latter impinged on our coast, bringing with 

 it enormous quantities of Scandinavian rocks. Many years ago 

 Prof. Sedgwick described the cliffs of bowlder clay at Holderness 

 as containing " an incredible number of smooth round blocks of 

 granite, gneiss, greenstone, mica slate, etc., resembling none of the 

 rocks of England, but resembling specimens derived from various 

 parts of the great Scandinavian chain." These are mixed, how- 

 ever, with a number of British rocks from the north and west, in- 

 dicating the meeting ground of the two conflicting ice-sheets. 

 Similar blocks occur all along the coast as far as the cliffs of Cro- 

 mer in Norfolk. Across the peninsula of Flamborough about two 

 miles west of the lighthouse there is a moraine ridge contain- 

 ing a few Scandinavian bowlders, but mainly composed of British 

 rocks. These latter consist of numerous carboniferous rocks 

 from the north and northwest, together with many of Shap granite 

 a peculiar rock found only on Shap Fell in the eastern side of 

 the Lake District, together with a few of Galloway granite. 

 These facts, it will be seen, add further confirmation to the theory 

 of great confluent ice-sheets indicated by the ice-markings upon 

 the various groups of mountains, while it is hopelessly impos- 

 sible to explain them on any theory of local glaciers, even with 

 the aid of submergence and of floating ice. 



The study of our British erratics has been assiduously pursued 

 for many years past by a committee of the British Association ; 

 and by means of a map showing the chief facts collected up to this 

 date, kindly furnished me by Mr. Percy F. Kendal, secretary of 

 the committee, I am able to give a brief sketch of the more im- 

 portant of the phenomena, and their bearing on the extent and 

 motion of the British ice-sheet. The general reader may be in- 

 formed that great numbers of rocks are so local and so character- 

 istic, often being confined to a very limited district or to a single 

 mountain, that the origin of a considerable portion of the errat- 

 ics can be ascertained with the greatest certainty. 



Taking first the Shap granite, which has already been men- 



