170 G. H. Kinahan — Re-arranged Glacial Drift. 



in the south-east of Ireland. In the area comprising the greater 

 portion of the co. Wexford, and the south-east part of the co. 

 Wicklow, it is quite apparent that prior to the glacial period the 

 principal valleys were more or less excavated or opened along lines 

 of breaks and other weak portions of the subjacent rocks. Afterwards 

 some of these valleys were obliterated by large accumulations of 

 Boulder-clay drift ; while others, as Dana has pointed out of other 

 places, were during the glacial period occupied by sub-glacier rivers. 

 Subsequently some of the filled valleys were more or less re-exca- 

 vated, and during the Esker sea period most, if not all, of them 

 below the 250 feet contour line were filled by shelly drifts, to be 

 again re-excavated in more recent times, partly by marine and partly 

 by meteoric denudation. 



During the " Esker sea period " the area we are now considering 

 was an archipelago, studded with various shoals and islands, the 

 largest of the latter being the land that is now known as the Forth 

 or Three Eock Mountains ; and through this archipelago the principal 

 currents seem to have flowed from the southward towards the 

 northward.^ 



^ Off the present coast of south-east Ireland the principal current runs from 

 south towards north ; and from the headlands, bars and banks extend northward, in 

 which the materials become finer as we proceed in that direction ; while westward, or 

 inside these bars and banks, fine materials are accumulated. On the coast south of 

 the headlands, which are open to the full force of the current, the accumulation is 

 well-washed sand, gravel, or shingle : and, as similar relations exist between the dif- 

 ferent deposits and the ancient islands and shore-line of the sea of the " Esker 

 period" in this part of Ireland, we are led to believe that then, as now, the principal 

 current flowed from southward to northward. It is commonly believed that the 

 chalks and flints found in the drifts of the cos. Wicklow and Wexford come from 

 Antrim in the north of Ireland. I, however, see no reason for such a supposition ; for 

 if they came thence, the drifts, as we proceed northward along the coast through the 

 counties of Dublin, Meath, Louth, and Down, ought to become more and more 

 chalky, which is not the case ; for when we proceed northward out of Wexford, we lose 

 all the great marl deposits, such as would be formed from the denudation of chalk. 

 The marls of Wexford and the adjoining portion of Wicklow would seem to be the 

 washing from some of the. chalk in England or France, while the sands associated with 

 the marls are similar to the detritus formed by marine or meteoric abrasion from the 

 associated rocks of the greeusand formation. Furthermore, the pieces of chalk found 

 in the drift are more like the hard beds in the English chalk, the " Chalk rock " of 

 Whitaker, than any of the Antrim chalk. Mr. Wyley, however, who has carefully ex- 

 amined the counties Wicklow and Wexford, thus writes : — " That the chalk flints are 

 from the Irish chalk, not necessarily from Antrim, is proved by the following consider- 

 ations. A very large proportion of the flints are altered into jasper of various sorts ; 

 many are agates and chalcedonys, which are only found when the chalk has been 

 subjected to strong volcanic action, as in the North of Ireland. Besides, I have in 

 my possession a flint, picked up near Carn Point, with a peculiar coral, at once 

 identified by the late Mr. G. V. Du Noyer as similar to ones he had seen in the 

 chalk of the North. The abundance of these flints and jaspers at Carn Point and 

 thereabouts, as well as in the bight of Cardigan Bay, at Aberystwith, etc., on the 

 same parallel, simply arises from the continual tidal action grinding all into sand 

 and mud except the flints. These I consider are all out of one of the drifts, and 

 that not the marl ; probably the old glacial drift, which, as indicated by the rock 

 markings of the district, came from the N.W. It is barely possible, as the chalk 

 or its equivalents extends through Belgium and Northern and Eastern France to 

 Northern Germany and east of the Elbe in Bohemia and still further eastward, they 

 may at one time have possibly extended to the valley between Carn Point and the 

 Welsh coast, the present fc>t. George's Channel. In the great limestone plain of 



