Yol. 51.] GBANOPHYEE AND THE GEAINSGILL GEEISEN. 



133 



ores, and. apatite of certain parts of the granophyre to the effect of 

 gravity, whether operating on the fluid magma or on minerals 

 crystallized out at an early stage. 



As already remarked, the tracts occupied by granophyre are often 

 covered by peat-mosses and other superficial accumulations, and the 

 precise limits of the intrusions are in some places a matter of con- 

 jecture ; but all that can be observed favours the view that the 

 basic modification of the rock is a marginal phenomenon, and comes 

 in near the contact of the granophyre with the gabbro. The gabbro- 

 intrusion we know to be of somewhat earlier date than that of the 

 acid rock, but it is highly probable that the interval between the 

 two was a short one, so that the acid magma was intruded among 

 rocks already hot. We should not, therefore, look for a marginal 

 concentration of the earlier products of crystallization in the grano- 

 phyre, such as we have found evidence of in the gabbro ; and the 

 phenomena here considered must be different in kind from those 

 discussed in my former paper. In proof of this it must be re- 

 marked that the basic margin to the granophyre is found (so far as 

 our knowledge goes) only where that rock is in contact with the 

 gabbro. For example, the granophyre about Eae Crags and to the 

 south, which is in contact with the later intrusion of diabase, is of 

 a thoroughly acid type (specific gravity 2-647). 



These considerations suggest that the curious modification of the 

 Carrock Fell granophyre on its southern border is due to a reaction 

 between the acid magma and the highly basic margin of the pre- 

 viously consolidated but still hot gabbro. It will be seen that this 

 idea is confirmed by a closer examination of the rocks in question. 



12. Junction op the Geanophybe with the Gabbeo. 



The junction of the granophyre with the gabbro is best observed 

 in Furthergill. The following section is seen in a distance of 3 or 

 4 yards from north to south, low down in the little sike, just before 



Fig. 1. 



IWtlier&ill Sike 



the outcrops are lost under the alluvial fan. No. 1 is granophyre 

 of specific gravity 2-705, and doubtless of considerably less acid 



