118 MR. J. MORRISON ON [vol. lxxiv. 



account of the Shap granite and its metamorphic aureole a descrip- 

 tion of some dykes 1 occurring in the Stakeley Valley, which, 



' while presenting a considerable range of differences, have at the same time 

 some curious points in common. Further, while they have characters which 

 seem to connect them on the one hand with the Shap-Fell granite, and par- 

 ticularly with its darker patches, they are unmistakably linked on the other 

 hand with the normal type of " mica-traps " found at greater distances from 

 the Shap-Fell intrusion.' 



The following year, in a paper on ' The Lamprophyres of the 

 North of England,' 2 Dr. Harker gave reasons for connecting the 

 whole series of lamprophyric - dykes — extending from Teesclale to 

 Furness and from Ingleton to Bassenthwaite — with the Shap 

 plutonic mass. 



Lastly, two d} r kes occurring at the head of Long Sleddale 

 Vallev were briefly described by Dr. Harker in ' The Naturalist ' 

 for 1912, pp. 266-67. 



III. General Remarks on the Intrusions. 



The intrusions discussed in the present paper occur in an area 

 extending from Shap in the north to Kendal in the south, and 

 from Windermere to Sedbergh in an east-and-west direction. 

 Within this area, forming a triangle with apices at Shap, Winder- 

 mere, and Sedbergh, are found most of the dykes the direct 

 connexion of which witli the plutonic centre can be regarded as 

 definitely established. Every intrusion mapped by the officers of 

 the Geological Survey has been visited, and careful search has been 

 made for intrusions not hitherto recorded ; but, in a region such 

 as this, many difficulties await the investigator. The country 

 consists of mountain and rolling heather-covered moorland, 

 interspersed with peat-bogs and intersected by deep river-courses. 

 A glance at the Drift edition of the 1-inch map is sufficient to 

 reveal the large extent of ground which is unavailable for the study 

 of igneous intrusions. All the low-lying land and much of the 

 high is covered with drift or peaty deposits, often of great depth. 

 In places along the hillside small patches of bare rock may appear ; 

 but great stretches of country-rock are obscured by a thick mantle 

 of drift, and the highest crags and river-channels alone afford a fair 

 field for investigation. But the drift in the river- valleys is often 

 50 feet deep, and only where the river has cut down to the floor 

 of the old valley are the rocks revealed ; while the denuding 

 action of the stream loosens the boulders, often of great size, 

 which accumulate in such force that all trace of the underlying 

 country-rock is obliterated. In a drift-covered country the time 

 element is important; dykes exposed at one period may be com- 

 pletely buried at a later. This has evidently been the fate of 

 several dykes mapped many years ago by the officers of the 

 Geological Survey, but of which not a trace remains. 



1 Q. J.G.S. vol. xlvii (1891) pp. 287-88. 



2 Geol. Mag. dec. 3, vol. ix (1892) p. 199. 



