G. H. Kinahan—On ''Middle Gravels" (?), Ireland. 267 



gravels do not occur associated with them, and no trace of the high 

 level shell-gravel has hitherto been discovered. 



When I wrote on the E.skers of the central plain of Ireland in the 

 paper ^ referred to by Mr. Geikie, my conclusions were nearly 

 altogether drawn from the phenomena presented by the Eskers, and 

 from them I concluded that the margin of the Esker-sea in western 

 Ireland must have been about 250 or 350 feet higher than at 

 present. Since then I have had opportunities of examining the 

 valleys in the hill counties of Cork, Kerry, Limerick, Clare, Galway, 

 and Mayo, and am not surprised to find that, in these different 

 counties, there are traces of a well-marked ancient sea-margin, 

 about 300 or 350 feet above the Ordnance datum line, proving 

 that what I suggested, from the facts given by the eskers, is borne 

 out by quite independent data. Some of the facts relating to the 

 upper and lower gravel terraces have already been published in the 

 Memoirs of the Irish Branch of the Geological Survey, while those 

 of Yarconnaught and South Mayo will, I hope, shortly be described 

 by my fellow-workers. 



Now to return to the supposed "■ middle gravels" of the east coast. 

 If the section between Killiney Hill and the drift cliff immediately 

 south of the mouth of the Shanganagh Eiver is examined, it will 

 in part be like Prof. Hull's sketch section ; that gentleman's 

 section, however, toward the south is incorrect, as his "middle 

 gravels " do not occur in a basin, but continue to the Bray Eiver, 

 lying on a denuded surface of the Boulder-clay drift, the latter in 

 places disappearing below the present sea-level, these depressions 

 being due to faults in the drift, a well-marked step fault being 

 exposed at the south end of the section, at the site of the Bray river 

 Martello tower. In this section the accumulation over the Boulder- 

 clay drift shows that the "Shell gravels" may graduate into clayey 

 gravels (in places somewhat like a Boulder-clay drift), or even into 

 a brick clay, while in places beds of gravels occur in the underlying 

 Boulder-clay; these beds, however, not being separate members of 

 the group, but rather integrants of the whole. Prof. Harkness 

 agrees with me that there is no deposit between Killiney Hill and 

 Bray Eiver that could possibly be called an Upper Boulder-clay drift. 

 This observer believes in an Upper Boulder-clay drift, but in other 

 localities. Of the Upper Boulder-clay drift he states that it is 

 seen in the railway cutting between Brayhead and Greystones, but 

 is in perfection at Castle Ellis, Co. Wexford; the latter locality, 

 quoting from his letter, "affords the clue to all the shelly sands and 

 gravels of Ireland." To me it appears that here or elsewhere a 

 Boulder-clay drift bed may lie on " shelly sands and gravels," and 

 yet not prove that there are three divisions in the drift, for if a 

 large glacier ends in the sea (such as the Humboldt glacier in Smith's 

 sound), the place must be marked by variations in the deposits, a 

 shelly sand and gravel forming during a warm year, or series of 

 years, while subsequently if a cold year or years follow there would 

 be a Boulder-clay accumulation, thus in successive years forming 



^ "Notes on some of the Drift in Ireland," by G. H. Kinahan, Dubliu Quart. 

 Journ. of Science, vol. vi., p. 249. 



