part 2] THE SHAP MINOR INTRUSIONS. 117 



deserved, no systematic examination of the minor intrusions has- 

 yet been made. Various dykes and sills have been mapped by the 

 officers of the Geological Survey from time to time, and their 

 position and character have been recorded in the various Memoirs 

 dealing with the district, while some have been more or less inci- 

 dentally described by different workers in the area. But no attempt 

 has hitherto been made to view them as a whole, or to trace 

 their bearing on the subsequent igneous history of the district , 

 and thus the phase of minor intrusions as such still requires 

 attention, in order to elucidate and co-ordinate the successive 

 stages of the final episode in connexion with the igneous activity of 

 which the Shap granite was at once the focus and the culmination. 

 In the present paper an attempt is made to examine the intru- 

 sions from the above-mentioned standpoint, and its scope may 

 be briefly indicated. A review of the acid intrusions will be 

 followed by a description of two groups of intermediate com- 

 position. Special occurrences will be noted, and the relationship of 

 the various groups will be discussed in connexion with their relation 

 to the plutonic centre. Evidence will be given bearing on the 

 succession of types that were evolved during the phase of minor 

 intrusions. 



II. Previous Work. 



The dykes mapped by the Geological Survey appear mainly 

 on Quarter-sheets 102 S.W. (New Series 30) and 98 N.E. (New 

 Series 30), with a few additional occurrences on adjacent sheets. 

 In the various Memoirs dealing with this area brief accounts were 

 given of the intrusions mapped. No attempt was made to describe 

 them in detail ; but three varieties were noted and a threefold 

 classification adopted : — (1) granitic dykes ; (2) micaceous dykes or 

 mica-traps ; (3) felsitic dykes. The first-named were stated to be 



' found within a distance of 4 miles south-east of the Shap granite from 

 which they are probably spurs. They resemble the Shap granite in litho- 

 logical character, and contain the same large crystals of pink felspar.' * 



All the dykes were assigned to one or another of these three 

 groups. 



In IS 79 Prof. T. G. Bonney, in a paper read before the Geological 

 Society, 3 described a number of lamprophyre dykes occurring in a 

 somewhat irregular line from Windermere to Dent. He distin- 

 guished between minettes and kersantites and felsitic varieties of 

 each, which he named minette-f elsite and kersantite- 

 porphyrite respectively. Several analyses by P. T. S. Houghton 

 were included. 



In 1891 Dr. A. Harker & Prof. J. E. Man included in their 



1 'The Geology of the Country round Kendal' Mem. Geol. Surv. 1887, 

 p. 35. 



2 Q. J. G. S. vol. xxxv (1879) pp. 165-79. 



k2 



