^34 



C. GALLAWAX ON THE GKAIQTIC AND 



rocks just described, while along the north-western side runs a wall 

 of strata of the metamorphic group. The only rock which appears 

 in the interval is a mass of coarse diorite, which projects from the 

 sands about midway between the two schistose series. In this line 

 of section, then, the two groups are separated by igneous rock, 

 apparently an intrusive mass. 



Continuing the section, we find the beds for the first half-mile 

 lying anticlinally, and consisting of quartzites of the older type, 

 quartz-schist, mica-schist, and subordinate bands of chloritic or 

 talcose schist. We then come in succession to quartz-schist "WT-th 

 garnets, talcose or chloritic schist, and a considerable thickness of 

 quartzose schist. A mass of diorite next appears. Beyond this is 

 a beautiful silvery schist, underlain by a black variety, much more 

 strongly foliated than the black schist of the younger group. Then, 

 for a considerable distance, the prevailing rock is green micaceous 

 and talcose schist*. These rocks I followed to within a mile and a 

 half of Dunree Head. The dip of most of the above schists is to 

 the S.E., and there is frequent contortion.. I was prevented from 

 visiting the section beyond ; but the rocks on the same strike to the 

 N.E. and S.W. are quartz-schists. 



Prom Dunree Head to Dunafi" Head. — Dunree Head terminates 

 the quartzite range over which the pass of Mamore is carried. It 

 is composed of easterly-dipping quartzite, and the same rock forms 

 the precipices which overhang Lough Svnlly for nearly three miles to 

 the north, and again appears in Lenan Head, north of which the 

 granite soon comes in, and is continued to Dunaff Head. Mr. 

 Cruise informed me that this fine headland is composed of granite 

 and quartzite. 



The superficial appearance presented to us by the traverse N.W. 

 of Ba%narry Bay is that of a considerable thickness of quartzite, 

 overlain by a great succession of quartzose, micaceous, and talcose 

 or chloritic schists. This series is certainly quite distinct from the 

 rocks between Buncrana and Derry. It nowhere presents under 

 the pocket-lens, so far as I have seen, any traces of a clastic struc- 

 ture. The schists are well foliated. They do not, indeed, suggest 

 the highly crystalline rocks of the Hebridean system, but they are 

 on the other hand easily distinguished from the partially minerahzed 

 schists of the Lough-Fojde series. 



It is also to be noted that, while the older rocks dip almost uni- 

 formly to the S.E., the dip of the Lough-Eoyle group is north- 

 westerly. That this is not a true sj^nclinal structure is evident from 

 the great dissimilarity between the rocks of the two sides of the 

 apparent basin. 



Section from Malin to Malin Head. 



This traverse is substantially the same as that part of the last 

 section which passes over the older series. Between the village of 

 Malin and the quartzites of the west coast, a breadth of about three 



* I do not commit myself to a definite opinion on the exact mineral nature 

 of some of the schists of this region. 



