O'Reilly — On Jointing in Bocks about Dublin, 8fc. 121 



Malahide Strand — continued. 



363 

 364 

 365 



366 

 367 

 368 

 369 

 370 



371 



372 



373 



374 



375 

 376 



377 

 378 

 379 

 380 



Crossed by jointing -without spar, . . . . 



Very extended jointing, forming a " gash" system 



"Well-marked open jointing, without spar (running to- 

 wards Howth Church), ...... 



Three " gash" veins on road side of last -mentioned. 



Set of thin spar joints, ...... 



Simple joint cutting these, ...... 



Thin spar joint, very extended, . . . . . 



Beds nearly horizontal here, the spar joints frequent ; 

 simple joint crossing these vertically, 



Set of simple open joints, cutting these beds ; well- 

 marked and continuous, ...... 



Well-marked joint, deep, crossing the beds, and dipping 

 south (running towards depression on Lambay Is., 



Beds rising here towards south, and traversed by jointing 

 at ......... . 



Also by simple jointing, ...... 



(About 100 yards north of Martello Tower.) 



"Well-marked fault in these beds. ..... 



"Well-marked 1 in. Dolomite joint, corresponding to di- 

 rection of depression, ...... 



Dolomite joint near road, 70 to 80 yards north of Tower, 



Joint forming face of rock, looking towards Tower, 



Double joint (fault) under Tower, . , . . 



Dolomite mass, looking towards Ireland's Eye, 



Contact of contorted and nearly vei-tical shales, with 

 limestone on which the Tower is built. 



Direction of it about, . . 'N'^- 95°-100' 



„ 80°-85° 

 Direction of vertically cleaved 

 shales, 40 yards south of 

 Tower, . . . . ,, 93° 

 Direction of shale beds, dip- 

 ping north at about 70°, . ,, 87°-90° 



E. 



E. 



74° E. 



26°-27° E. 



7°-8° E. 



7°-8° W. 



59°-60° "W. 



3° "W. 



64°-65° 



7°-8° 

 72°-73° 



381 



Dii-ection of most southerly outcrop on the 

 Strand," 



E. 

 E. 



Velvet 



14°-15° W. 



N""- Sm- 



53°-54° W. 



29°-30° E. 



29° E. 



24°-25° "W. 



62°-63° "W. 



24°-25° W. 



80° 



W. 



Donabate Coast :- 



382 Joint in boss of Cambrian, 50 yards south of MarteUo 



Tower, ........ 



383 Feldspathic lode or vein, 1 ft. thick, in slate, running 



towards Lambay Is., 



384 Same, near the Tower, ..... 



385 Vertical joint in boss of slate rock, north of Tower, 



386 ,, ,, ,, compact greenstone. 



42°-43° 



E. 



57°-68° 



W 



80°-85° 



w 



65° 



E. 



67°-68° 



E. 



