Part of Carnarvonshire. 



13 



ridge — commonly known as the St. A.nnes-Llanllyfni ridge — stretches 

 from St. Amnes in the Nant-Ffrancon Valley to the village of 

 Llanllyfni in the Nantlle Valley. This ridge is 12 miles long and 

 has a south-westerly trend ; it is therefore roughly parallel to the 

 Carnarvon-Bangor ridge, from which it is distant about 2 miles. It 

 is with the area at the south-west end of the St. Annes-Llanllyfni 

 ridge that the following remarks are concerned. The object of my 



GEOLOGICAL 5KETCH MAP 

 OF NORTH WEST 



JpOynnog 



/jrvtVcA Bwlchmdwf 



R#t Camhtien 



Cambrian* 



Ftv-Cambnan 



/ 



MAP I 



Mynydd 

 ICenin 



investigation lias been to establish the succession of rocks in this 

 area, and to correlate it, if possible, with the main portion of the ridge 

 lying to the north-east. The results are set out in detail in the 

 following pages. Text-map I shows the position of these two Pre- 

 Cambrian ridges and also the extent of the area to be considered in 

 detail. 



