lxxii PROCEEDINGS OF THE GEOLOGICAL SOCIET5T. [May I906, 



to draw attention, not only to the composition of the rocks (which 

 is responsible for the three different types of scenery marking the 

 tracts occupied by the Skiddaw Slates, the rocks of the Borrowdale 

 Series, and the Upper Slates respectively), but also to certain planes 

 and belts of weakness which are particularly noticeable among the 

 rocks of the Borrowdale Series. These belts are largely due, at 

 any rate, to the movements which affected the district in Devonian 

 times. Their nature, so far as I understand them, has been grasped 

 owing to detailed work among the old rocks, armed with the 

 knowledge supplied by previous writers, and especially owing to 

 the publication of the various maps and memoirs of the Geological 

 Survey. Especially significant are three sets of lines traced in 

 detail upon the Government geological maps, namely: the line which 

 separates the Skiddaw Slates from the Borrowdale Series, chiefly 

 mapped by Clifton AVard ; that between the Coniston Flags and 

 the Coniston Grits ; and those which cut across and displace the 

 Coniston Limestone, and disappear against the second line. The 

 accurate mapping of these was largely due to W. Talbot Aveline 

 and the surveyors who worked under him. 



Of late years the significance of these lines has been impressed 

 upon my colleague Mr. Harker and myself, and a brief sketch of 

 our views with regard to them has been published in a paper 

 entitled ' Notes on the Geology of the English Lake District.' * 

 I may be pardoned for stating that the clue to their significance 

 was first obtained by me, as the result of the detailed working-out 

 of the fossil zones of the Stockdale Shales. This work, of a purely - 

 stratigraphical character, in fact, led me directly to prosecute the 

 studies upon the physical history of the district of which the present 

 Address is the outcome, and I mention it to show the importance 

 of detailed geological work to the geographer. 



With these brief references to previously-published work, I 

 may now proceed to consider the subject of my Address under the 

 following heads : — 



i. Events prior to the uplift which produced the dome, 

 ii. Production of the dome, 

 iii. Initiation of the drainage-lines, 

 iv. Effects of the three types of rock upon the scenery. 

 t. Modification of the old drainage-lines along shatter-belts, 

 vi. Depression of the outskirts of the district, 

 yii. Effects of meteorological conditions : (1) hill-outlines ; (2) the 



Glacial Period, 

 viii. Conclusion. 



1 Proc. Geol. Assoc, vol. xvi (1900) p. 449. 



