O'Reilly — On the Waste of the Coast of Ireland, S^-c. 169 



intervals of two feet, cut the rock into slabs. In the Croaghaun clifPs 

 the dip changes from south-south-east to north-north-east or north- 

 east, and continues thus out to AchillHead, the master joints running 

 parallel to the line of cliifs. Along the shores on the south, Moyteoge 

 Head presents a barrier of quartzite to the agents of denudation, thus 

 sheltering the inlet or bay of Keem from the south--westerly gales. 

 The bay is formed parallel to a line of fault. Further east the head- 

 land of Gubalennaum More stands forth in the comparative impenetra- 

 bility of quartzite, being carred out along the lines of Jointing — the 

 indentations of Dooagh and Keel are cut in along the line of strike." 



(p. 13.) — " On the east side of Keel Bay, in the Minaun Clifis, the 

 strike bends more and more to the north-east, the jointing continuing 

 approximately at right angles to the dip. From Doonty Fighter, the 

 southern point of the quartzite cliffs of Minaun, the coast-line, as a 

 whole, trends to the south-east, the schists becoming softer, more 

 micaceous, steatic, and chloritic as we go south, and this portion of 

 the coast being more exposed to the south-western gale has run at the 

 southern end of the island away to a point. It is yery noticeable that 

 the coast-line throughout is approximately either at a yery high angle 

 or at right angles to the direction of the dip. 



"Achill Sound itself appears to have been formed by a gi'adual 

 subsidence of the land, the direction of the coast-line being approxi- 

 matiyely parallel to the line of the strike of the rocks, yiz. north- 

 north-east and east-south-east, and frequently coinciding with that of 

 the major joints. On both the eastern and western shores also, the 

 bog is found running down on the beach, and forming banks at the 

 level of high tide." 



(p. 14.) — " At Ooghrelleyrannell there is a cavern cut in along the 

 joint lines called the ' Seal Cave.' " 



(p. 15.) — ^^ From Saddle Head to Achill Head. — Very fibrous, and 

 highly felspathic, coarsely crystalline gneissose schists. Cliffs dan- 

 gerous, and almost inaccessible." 



(p. 17.) — "At the east side of Keel Bay in the Minaun or 

 ' Cathedral Cliffs,' the sea having excavated passages through pro- 

 jecting points along the joint planes, we find the coast-line and head- 

 land of hard, flaggy, and tabular quartzites, with occasional bands of 

 argillaceous and other schists. We here notice in all the more 

 weathered parts, i. e. those cut into the cliff, that the direction of 

 the dip is at right angles to that of the most weathered face of the 

 cliff." 



(p. 18.)—" In Achillbeg Island. The coast-line here is very 



