Yol. 62.] ANNIVERSARY ADDRESS OF THE PRESIDENT. lxxxi 



of the anticline and in the Falcon-Crag Group on the south), or where 

 the rocks have been exceptionally resistant, that continuous outcrops 

 are traceable. Elsewhere the outcrops often occur in eye-like 

 patches surrounded by vegetation. 



Of other changes which took place during this period little need 

 be said. It has already been stated that the Ennerdale Granophyre 

 and perhaps the Eskdale Granite are apparently of the age of the 

 Borrowdale Group. Igneous rocks were certainly forced among 

 the Lower Palaeozoic rocks in Devonian times — for instance, the 

 granites of Skiddaw and Shap ; but the exposed area of these rocks 

 and of the rocks which have been affected by their metamorphism 

 is too small to produce much effect upon the present physiography. 



The wide distribution of the cleavage impressed on the old rocks 

 of the district in Devonian times is well known. Along two belts 

 it is especially prominent, and in the northerly belt especially it is 

 somewhat oblique to the strike of the beds. Each belt is in the 

 rocks of the Borrowdale Series. The northerly one begins just east 

 of Borrowdale near Lowdore, passes through Castle Crag over 

 Scawdel and through Honister Crag. The southerly one is much 

 more extensive : starting in Wet Sleddale near Shap, it crosses the 

 valleys of Long Sleddale, Kentmere, and Troutbeck, past Kydal and 

 the Langdale valleys, Tilberthwaite, and the summit of Coniston 

 Old Man, to die out in the Duddon Valley. Important as these belts 

 are geologically, the rocks in them do not profoundly affect the 

 physical geography of the district. Here and there depressions 

 have been worn along them, but they usually traverse hill and 

 dale alike, as is well seen in the Coniston group of fells. 



The date of the peculiarly-flinty type of alteration which affects 

 the rocks of the Scawfell group of fells is not yet determined, 

 nor has the cause of the alteration been actually settled. The 

 occurrence of violently-folded structures and brecciation in the 

 banded ashes of these flinty rocks and of the slate-belts alike, 

 and their similarity to structures in some of the Upper Slates, points 

 to the folding and fracture being in the three cases post- Silurian ; 

 and as this folding and fracture certainly occurred before the flinty 

 alteration of the rocks, the probability is that this alteration is also 

 post-Silurian. Whatever its date, its occurrence is very important in 

 determining the detailed structure of the Scawfell group of fells. 



It is well known that, during the period of the Devonian move- 

 ments, the rocks of the Lake District were subjected to extensive 



