Vol. 50.] THE GABBRO OF CARROCK FELL. 315 



fault, there must be a considerable downthrow to the north, but there 

 is reason to believe that very little of the gabbro is lost by the break. 

 Eoth granophyre and gabbro form steep cliff's to the eastward, 

 facing the alluvial flat of the Caldew, and they make no further 

 appearance in that direction. This is probably due to their natural 

 termination, and not to any fault. It is certain, at least, that the 

 Eycott lavas come up to the intrusive masses on this side, for they 

 are seen in the face of the gabbro cliff and on the heights above. 

 The relations are not those of a simple junction of the intrusive 

 rock with the lavas along a definite line. As one climbs up the 

 cliff, e. g. at Snailshell Crag, sometimes gabbro, sometimes lava is 

 seen, or the two together in intricate association, making it clear 

 that large portions of lava have been enclosed by the molten gabbro. 

 The same relations are shown at the top of the cliff, and the Eycott 

 rocks occupy much of the ground along a W.N.W. line from here to 

 Iron Crags, a distance of a mile or more. They are not continuous, 

 but occur in large detached patches embedded in the gabbro and 

 penetrated by countless veins of that rock. They give the idea of 

 having been partly buoyed up by the molten gabbro-magma, which 

 nevertheless welled up in every crack that was formed. A com- 

 parison of these phenomena with what is seen in the cliff near Snail- 

 shell Crag and Black Crag shows that the lavas must pass right into 

 the gabbro-mass in the direction named, which is that of their strike. 

 The remnants which are seen, embedded in gabbro, between Mose- 

 dale and Iron Crags are highly metamorphosed, but still easily 

 recognized. The well-known and beautiful porphyritic lava (No. 4 

 of Ward's section l ), the less markedly porphyritic lavas which 

 succeeded it, and certain tuff-beds are clearly distinguished, and, 

 what is more remarkable, they seem to occur in their proper order, 

 and certainly follow their normal strike. It appears that the gabbro, 

 forced in probably along the base of the Eycott group, has not only 

 disturbed and lifted the lavas, but in some measure bodily engulfed 

 considerable stretches of them. The Eycott group in this district 

 has a very steep dip to N.N.E., and the mass of gabbro seems to have 

 a similar inclination. Whether at the time of the injection the 

 volcanic rocks lay more nearly horizontally is not evident from the 

 mapping. I have found no lavas associated with the granophyre 

 or the diabase. The remarkable patches of Eycott lavas enclosed in 

 the gabbro did not escape the notice of Mr. Ward, who noted the 

 occurrence of ' trap in hypersthenite ' in the neighbourhood of 

 Mosedale. I cannot, however, endorse his statement that the one 

 rock passes into the other ; the junction of the two is always of such 

 a nature that both rocks can be clearly exhibited in one microscopical 

 slice. The supposed transition was one of the grounds on which he 

 based his suggestion of a metamorphic origin for the gabbro and its 

 associated rocks. 



The geological relations of the diabase need not be discussed at 

 this point. I shall show reasons for believing that its intrusion 

 1 Monthly Microsc. Journ. vol. xvii. (1877) p. 241. 



