October 1, 1898.] 



KNOWLEDGE 



219 



which little icebergs began to float. Here and there, the 

 sea may have encroached upon it, bringing in marine 

 shells, which became broken up and mingled with terres- 

 trial gravels poured down from the glaciated hills. 



The precipitation continued in excess. The lakes and 

 pools froze over throughout the year, and were lost beneath 

 the mantle of freshly-falling snow. On all sides, from the 

 slopes of the Kerry ranges, from the broad back of 

 Leiuster, from the high cirques of Mayo and Connemara, 

 and from limestone uplands now altogether lost to us, 

 glaciers crept down, spreading out in terminal fan-like 

 forms, and finally coalescing in the plain. When the 

 plain itself became full of ice, minor details of surface 

 would cease to exert an influence, and the great lines of 

 ice-movement asked for by Mr. Close in his memorable 

 paper may have been set up across the lowlands. The 

 old extension of land southward and westward, of which 

 we have so much evidence, may easily have provided 

 nooks and corners, particularly on its seaward border, in 

 which the early elements of the Irish fauna and flora could 

 find refuge from these rigours for a time.t 



We are not now concerned with the climax of the 

 Glacial epoch, about which so much has been written, 

 and about which we know so little. It is of small moment, 

 moreover, in considering our eskers, whether part of the 

 striation of our rock-surfaces was due to the movement of 

 floating ice, J or whether it must be ascribed to ice-sheets 

 of the magnitude demanded by Prof. Jas. Geikie and 

 Mr. Close. The eskers belong to the latest phase, and 

 overlie the boulder-clays and gravels, about which con- 

 troversy is so often raised. It is now almost impossible, 

 at any rate, to suggest a marine origin for the eskers. 



Prof. SoUas's map of the Irish plain, from Galway to 

 Dublin, shows the distribution of eskers over a wide area ; 



Flo. 2. — The so\ith-west slope of the Esker at TTinon Castle. 



and he reasons carefully, from their knots and confluences, 

 as to their resemblance to river-courses beneath ice. Similar 

 evidence has been gathered, both from North America and 



* Op. cit., pp. 231, 238, and Plate VII [. 



f See Seharff, " Origin of European Fauna," Proe. S. Irish Acad., 

 3rd Ser., Vol. IV. (1897) ; and comments by Gr. C. Carpenter, Natural 

 Science, Vol. XI., pp. 382 and 385; and G-. Cole, Irish Naturalist, 

 1897, p. 240. 



% Grarwood and Gregorr, op. cit., pp. 215 to 217 ; Seharff, op. cit., 

 p. 494. 



Scandinavia ; and Prof. Russell's* description of the Mala- 

 spina glacier supplies exactly what the followers of Ilutton 

 and of Lyell demand — an example of " causes now in 

 action," capable of explaining the phenomena left us from 

 the past. 



The Malaspina glacier lies in south-east Alaska, between 

 the watershed that forms the Canadian frontier and the 

 Pacific. It is seventy miles wide, and twenty to twenty- 

 live miles long from front to back— (.c, its length, like 





FiQ. 3. — Section in the Esker at Green Hills, Co. Dublin, sliowing 

 irregularly stratilied gravels and purer sand below. 



that of so many " hanging glaciers " in the Alps, is con- 

 siderably less than its breadth. But it is not a hanging 

 glacier, cut ofl" in front along a line of clifl's ; it results from 

 the accumulation of snow and the confluence of normal 

 glaciers, which slip from the mountain -ranges to the north ; 

 and it lies, with a fairly level surface, on " the flat lands 

 between the base of the mountains and the sea." Hence 

 it has been styled a " piedmont " glacier— an unfortunate 

 term, when one thinks of the glaciers of Piedmont proper. 



The moraine-material borne by it is covered with snow 

 in the higher regions, and hence becomes " intraglacial." 

 But it shows itself along the melting border of the ice, as 

 a dark band some four to five miles wide. Forests of 

 spruce firs and other vegetation, as shown in Prof. Russell's 

 photographs, grow on this exposed material, which itself 

 rests on the lower layers of glacier-ice. This dense wood- 

 land, rising from the surface of the glacier, is a fine 

 example of the contemporaneous occurrence of a north- 

 temperate flora and of continental ice. Animals similarly 

 find a home on the ice, and their remains must become 

 embedded in strata belonging to this local glacial epoch. 



The area of the Malaspina glacier is one thousand five 

 hundred square miles ; but it is only fair to remember that 

 it is fed by some of the highest ground in North America. 

 Mount St. Elias, itself eighteen thousand feet in height, 

 supplies it on the north-west through the Libby and the 

 Newton glaciers. t The latitude of the district is sixty 



« Op. cit., p. 67. 



t See Russell's Map op. cit., PI. IV. ; and also Pis. V.. VII., 



