MONIAN SYSTEM OF E0CK8. 



Fig. 8. — Plan of Shore, west of Porth-y-ly-ivod. 



491 



1. Ashy pelite. 



2. Granite. 



3. Sea-sand, 



Passing up the eastern side, we find another junction at Melin 

 Ddrydwy, on the slope of the west bank of the stream. Here the 

 disposition of the granite and its neighbour is as shown in fig. 9. 



Fig. 9. — Section on West side of Stream at Melin Ddrydwy. 



1. Quartz-felspar porphyry. 2. " Halleflinta." 3. Pathway. 4. Eiver. 



The line between the two rocks is very clearly defined, but also 

 irregular. The granite appears on the upper, that is on the 

 western side. It would be difficult to regard this as anything but 

 an intrusive junction. The " granite," however, here is changed 

 into a quartz-felspar porphyry, the porphyritic crystals showing 

 signs of great pressure. 



We next arrive at Gualchmai. Here, just west of the road 



