1912-131 635 



to subaerial rather than marine denudation. The river, doubtless, 

 commenced to flow upon the surface of the newest basalts, in a 

 northerly direction ; and when, during erosion, it touched the 

 softer Cretaceous and Triassic strata, a gorge was formed which 

 ultimately expanded to form the present valley, pari passu with 

 the lowering of the river course. The resulting escarpment 

 presents a sublime array of natural features, extending in an 

 irregular sinus from Benevenagh in the north to Benbradagh in 

 the south. 



GEOLOGICAL FORMATIONS. 



A table is here given in which the formations are presented 

 according to age, in descending order ; but only those to which 

 special reference can be made in this outline. Indeed little can 

 be added to the published accounts regarding the Metamorphic 

 rocks, Carboniferous and Triassic strata, Chalk and Lias, partly 

 because they have been already well described, and partly because 

 they are largely concealed by drifts and later deposits. 



TABLE OF FORMATIONS, ETC. 



Peat. Boulder-Clay of Third Stage. 



Blown Sand. 

 Raised Beaches. 

 Glacial-flood Gravels and 



Warp-clays. 

 Moraines. 



Eskers, Esker Sands, etc. 

 Modified Boulder-Clay. 



Sand,Gravel, and Boulder Bed. 

 Boulder-Clay of Second Stage. 

 Boulder-Clay of First Stage. 

 Upper Basalt. 1 contemp- 



Interbasaltic Beds, oraneous 

 Lower Basalt. I with the 



Old Blackwater Alluvium. 



The last member of this series I introduce more or less 

 tentatively, hoping to give fairly satisfactory reasons for its 

 existence ; while also advancing reasons for a belief in its 

 continuance into, and prolonged deposition of, the series of beds 

 commonly known as the Lough Neagh Clays. That is to say, the 

 series continued throughout the periods of Lower Basalt, the 

 Interbasaltic Beds, and (in the upper reaches of the valleys at 

 least) the Upper Basalt, as well as subsequently, after the Glacial 

 Period, and even up to recent times, with their present alluvial 

 additions. 



