part 4] THE SCHISTS OF THE SCHICHALLION DISTEICT. 435 



accompanied by a rock resembling the Grey Schist. This limestone 

 is too massive to be regarded as a local intercalation in the Quartzite 

 Group. If, on the other hand, it be taken as Grey Limestone, as 

 I believe it to be, its method of occurrence needs some explanation. 

 It is true that, in the extreme north of the district, the Grey 

 Limestone comes near the lower margin of the Schichallion 

 Quartzite. But, in the nearer ground, immediately north of 

 Schichallion, the intervening members are strongly developed. A 

 line of movement has been suggested, in order to account for the 

 duplication of the outcrops of Schichallion Quartzite and Killie- 

 krankie Schist, and it is possible that one margin of the limestone 

 is a continuation of this line. Neither margin can, however, be an 

 ordinary fault-line, as both are much twisted, or folded, and there 

 is no visible sign of crush. It is possible that the explanation lies 

 in a folded rupture, which may either have been a normal fault, or 

 a thrust. Conceivably, two such faults are needed to explain the 

 relations. The general deformation and metamorphism of the 

 period of the folding may have destroyed the more tangible 

 evidences of movement. 



YI. Like oe Contact between the Dalradian Series 



AND THE StRTTAN FLAGS. 



A junction occurs on the banks of the Tummel, a short distance 

 east of Dunalastair, and 3 miles east of Kinloch Rannoch. As in 

 the ground north-east of Schichallion, the Grey Schist is the 

 marginal member of the Dalradian Series. The strata are here 

 nearly vertical, and, as the Flags are approached, little bands or 

 lenticles of rock of a siliceous type appear in the Grey Schist. 

 The margins of these bands are perfectly sharp, and there is no 

 gradation of type. Following the northern bank one reaches a 

 little trough-shaped hollow, which does not appear on the other 

 less accessible side of the river, and which there is no reason 

 to suppose is a fault-line. On crossing this, one passes from 

 thoroughly pelitic Grey Schist into an unbroken and typical 

 section of siliceous flags. 



The marginal belt of Grey Schist continues to beyond the 

 Errochty Water. The change from micaceous schist to siliceous or 

 semipelitic rocks of the flag group is always abrupt, and can some- 

 times be fixed within a few yards. Infolds or intercalations of 

 flagstone type are, however, sometimes found within the Gre} r 

 Schist, as in the Tummel section. 



At the northern end of the Dalradian outcrop, the border of 

 Grey Schist is present striking east and west, but considerably 

 thinned : it cannot be followed beyond this point. The Grey 

 Limestone, on the other hand, passes round the end of the syncline, 

 and may be traced for half a mile along its western side. Where 

 last visible the marble must be in close proximity to rocks of the 

 flagstone group, although the latter are not seen absolutely in place. 



Some time has been spent in attempting to trace the further 



