6 3 6 



IProc. J3.N.F.C, 



I assume that the term Interbasaltic Beds is familiar to all ; 

 and that they are known to consist of lithomarge formed in situ 

 from the Lower Basalt, with "pavement," a highly coloured red 

 lithomarge, both of which show a ^z/afo-stratification : these 

 underlie, either lignite, occurring often in thick seams, bauxite, 

 which in places shows evidence of sedimentation,* or iron ore 

 (black and compact or loose and pisolitic), which seems to have 

 been collected through alternate droughts and drenchings,f in 

 small lakes on the surface, and may in places show stratification ; 

 or yet again bole, a clayey iron-ore ; occasionally also conglom- 

 erates, the result of lake-shore erosion. 



BASALTS. 



The most casual observer cannot fail to be struck with the 

 extreme regularity of the basaltic layers presented in the 

 magnificent cliffs and headlands, which face the north coast, 

 from Bellarena to Castlerock along the Midland Railway Line. 

 However critically examined, such uniform lava-flows seldom 

 appear to be irregular, terminable or dovetailed with other flows 

 on the same horizons, and are highly suggestive of having been 

 originally very fluid basalts. From Benevenagh to Magilligan, to 

 a great height in the cliffs, they are characteristically amygdaloidal, 

 and are rarely columnar. 



In the vicinity and latitude of Keady Hill, however, and 

 further south, columnar structure is frequently to be seen, even in 

 the lowest layers, and amygdaloidal structure is not common. 

 Moreover, another structure such as that described by Sir Arch. 

 GeikieJ in the Sanday basalts, with alternating thin layers of 

 ophitic and granular basalt, is frequently to be seen in the area 

 east of Keady, and this peculiarly banded rock is occasionally 

 highly crumpled. I take these structures to indicate that the 



*Memoir. " Interbasaltic Beds of North-east Ireland," pp. 7, 31, 39, 50. 



10/. at., p. 8. 



+" Ancient Volcanoes," Vol. II., p. 190. See Note A at end of paper. 



