551.33(41.5) 172 



II 



The Eskers of Ireland 



OF the more recent geological phenomena none are more curious, 

 and none have given rise to more speculation, not to say con- 

 troversy, than the ridge-like accumulations, principally of sand or 

 gravel, found throughout the midland district of Ireland. 



Considering that geologists have very commonly associated these 

 ridges — eskers as they are called in Ireland — with the products of 

 glaciation, it appears to me not a little remarkable that they are 

 confined to a comparatively narrow zone running through the 

 flattest part of the island from Galway Bay to Dublin Bay. The 

 remark would apply with almost equal force to the corresponding 

 formations of Scotland and the Scandinavian peninsula. The kames 

 are nearly confined to the valleys of the Clyde and Forth, as the 

 asar of Sweden have their most striking development in the Lake 

 Malar district. True, there are mounds of gravel in some of the 

 northern counties of Ireland, but they are not to be confounded 

 with the typical eskers of Galway, King's County, North Tipperary, 

 Qaeen's County, Kildare, and Dublin ; and in Scotland the term 

 kame is applied to ridges and mounds " of marine, lacustrine, 

 fluviatile, and meteoric (wind-driven) drifts." 



" The centre of Ireland is chiefly a great plain of Carboniferous 

 Limestone, partly surrounded by several groups of lofty hills com- 

 posed of the oldest rocks, which rise from beneath the limestone. 

 The hills to the south of this plain have every height up to 3000 

 feet above the sea. Other hills, rising to heights of 800 or 1000 

 feet, are composed of Coal-measures lying on the limestone ; these 

 are surrounded by valleys which are branches of the great plain. 

 The general level of the limestone plain is from 100 to 300 feet 

 above the sea, only a few isolated hills of limestone in the interior 

 of the country rising to as much as 500 or 600 feet." 



From this description by Jukes, it is clear that, if the surface 

 of the country were depressed 300 feet from its present level, the 

 waters of Galway Bay would meet those of Dublin Bay, forming a 

 broad channel interrupted only by a few islands and occasional shallows. 

 That such was the case during at least a portion of the period of the 

 deposition of the limestone-gravel is generally maintained by Irish 

 geologists ; and the term ' esker sea ' (Kinahan) has been used to 

 denote the inland waters when the land depression was at or near 



