120 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1 894.- 



among other noteworthy features they record the abundant occur- 

 rence of andalusite, in idiomorphic crystals, usually coated with 

 little flakes of yellowish- or greenish-brown mica. 



The study of the adjacent dykes and sills has led to some very 

 interesting conclusions. Viewed as a whole, the neighbouring 

 intrusions, while they have characters which seem to connect them, 

 on the one hand, with the Shap Fell granite, and particularly with 

 its darker patches, are unmistakably linked with the normal type 

 of mica-traps found at greater distances. None of the various 

 intrusions alluded to can be traced as continuous with the granite 

 at the present surface, and the Authors suggest that, if they are 

 right in regarding them as apophyses, these are in connexion, not 

 with the visible granite-mass, but with a deep-seated extension of 

 it. When these apophyses are considered in conjunction with the 

 patches of darker rock caught up in the granite, they appear to 

 throw light upon several of the dykes penetrating the Lower Palaeo- 

 zoic rocks of the district, which abound within a radius of 15 miles 

 of the Shap granite. Numerous dykes, it is true, are found round 

 the other granite areas of the Lake District, but these are usually 

 felsitic, whilst the dykes more immediately in the neighbourhood of 

 the Shap granite consist both of felsites and mica-traps — the latter 

 chiefly on the east side, and especially in the region between Shap, 

 Kendal, and Sedbergh. In the neighbourhood of the Shap granite 

 both the felsitic and micaceous dykes have abundant porphyrinic 

 felspars, which imply a relationship to the granite itself, and such 

 felspars are found to become rare at a distance from that outburst. 

 As explanatory of these and other facts the Authors suggest that a 

 magma occurred beneath the Shap granite of more basic character 

 than the granite itself, and that from this the micaceous dykes 

 were sent out, whilst some of this basic material also was carried up 

 as ' clots ' in the fluid granite. These, it is presumed, constitute the 

 dark patches which attracted the attention of the late J. A. Phillips 

 and other observers. 



The nature of the Shap intrusion is further discussed, and it is 

 argued that the abnormal alteration of the rocks around a mass- 

 with so small a diameter would suggest the passage of molten 

 matter for a considerable period through the channel which is now 

 filled with granite. In all probability such molten matter was for 

 a long time forced from the underlying magma through this channel, 

 though whether it terminated in a laccolite or in a volcanic out- 

 burst there is no present evidence to show. The rocks seen to be 

 in contact with this old pipe are the Brathay Flags and other divisions 



