Yol. 65.] THE CAr/LDRON-StTBSIDEXCE OE GLEN COE. 651 



are inclined at 70° towards the north- north -east : the fault in this 

 locality is, therefore, distinctly reversed. The same feature is charac- 

 teristic of the dislocation in the Cam Ghleann, where the inclination 

 is again 70° in a north-easterly direction, and a reversed hade is 

 also found along much, if not the whole, of the northern front of 

 the subsidence. 



Next to the flinty crush-rock, and obviously chilled against it, 

 rises the broad dyke-like mass of fault-intrusion, which forms the 

 prominent little cliff of the Stob. The rock here is a typical 

 example of the coarse grey porphyrite type of the intrusion. For 

 the most part the chilled edge of the porphyrite follows the flow- 

 banding of the flinty crush-rock ; but, at one point, 1 it cuts across 

 this banding for a fraction of an inch, and isolates minute angular 

 fragments of the flinty crush-rock. Obviously then, the latter rock, 

 at this point, was solid when the porphyrite was still liquid. JBut 

 one need not conclude from this that the flinty crush-rock was 

 solid at the time of the upwelling of the fault-intrusion. On the 

 contrary, the small and frequently broken felspar crystals, en- 

 closed in the crush-rock, point to the continuance of viscous flow in 

 the latter after it had come into contact with some portion of the 

 fault-intrusion, for the felspars are almost certainly xenocrysts 

 derived from this intrusion. 



The dyke-like mass of the fault-intrusion forming Stob Mhic 

 Mhartuin is about 30 yards wide. After crossing it, we pass on to 

 quartzose schists striking south-east, a direction distinctly different 

 from the south-south-easterly strike of the quartzites on the south 

 (fig. 7, p. 649). Moreover, some of the beds here are inclined at 

 angles no greater than 40° : a marked discordance, therefore, exists 

 between the arrangement of the schists on the two sides of the 

 great line of flinty crush. The quartzose schists, too, are not 

 merely the twisted continuations of the quartzites already described : 

 for they are evidently more micaceous, and have been correlated, 

 though with some hesitation, with the Moine Group to which 

 reference has been made. They show signs of an irregular shearing 

 altogether later than their foliation, and also of reddening ; the 

 latter feature, however, is not strongly accentuated. 



When about 80 yards of these schists have been passed over, 

 another important line of movement is encountered running west- 

 north-west, parallel to the first. It has the same distinguishing- 

 characteristics, for the schists on approaching it become thoroughly 

 sheared and pass into a narrow ribbon of flinty crush-rock. Chilled 

 against this, as before, we find a broad dyke-like mass of porphyrite. 

 This is the early fault-intrusion already described at some length. 

 Not only is it chilled against the fault-line, which it borders, but it 

 has frequently suffered, both along its margin and in its interior, 

 from a recrudescence of shearing posterior to its consolidation. The 



1 Geologists -who may visit this section are asked to do no injury to this 

 ■exposure. 



