-1898] THE ESKERS OF IRELAND 247 
ing between the Silvermines and the Seve Boughta mountains behind 
Portumna. Last, not least, the great group of drift ridges and hills 
at Esker College, Athenry, is situated near the mouth of the great 
strait which occupied the valley of Gort and Lough Cooter between 
the mountains of South Galway and those of North Clare. 
Dr James Geikie remarks that Mr Kinahan was the first to 
point out the relation between these groups of post-glacial mounds 
and ridges with the openings of valleys branching off from the great 
central plain; and the circumstance is further noteworthy as form- 
ing (accidentally, I think) a connecting link between the two sets of 
theories represented by Kinahan and Geikie respectively. While 
Kinahan looks to the ‘ colliding’ or dividing of flow-tide currents, 
Geikie finds all that is necessary in the melting away of ‘ confluent 
glaciers. The latter regards the explanation which Mr David 
Hummel gives of the asar of Sweden as applicable to the drift for- 
mations of Scotland and (as he believes) to the analogous formations 
of Ireland, including, of course, the eskers. 
From the observations made by him on the asar and other 
drifts of Sweden, Hummel concludes that the facts indicate the 
agency of running water, and the direct action of glacier-ice ; and 
he comes to the conclusion that the asar have been formed in 
tunnels underneath the dissolving ice by running water introduced 
through crevasses, etc., acting on the ground moraines of the great 
confluent glaciers which covered Sweden during the glacial period. 
Geikie adopts a similar explanation of the kames of Scotland, and 
remarks that the theory to some extent resembles Mr Goodchild’s 
view of the origin of drift deposits in general. 
Dr N. O. Holst has proposed another explanation of asar, which 
he supposes to have been deposited in superficial channels licked out 
of the ice-sheet by the water derived from the melting of the inland 
ice. The materials were, as he believes, derived from the melting 
ice in which they had lain embedded. Geikie rejects the explanation 
for these reasons :— 
(1) Because asar, eskers, and ridgy kames are not so continuous 
as they must have been had they been formed in superficial river 
channels; and 
(2) Because we have no reason to believe that the ice of the 
old extinct glaciers was more thickly charged with debris than the 
present ice-sheets of arctic and antarctic regions. 
Moreover, it occurs to me that, while it is by no means im- 
possible that morainic matter may have collected in such grooves, it 
is very unlikely that it would come to terra firma without disturb- 
ance of stratification. The groove would be narrower at bottom 
than at top, the reverse of what we find in the esker. 
Hummel’s theory, as adapted by Geikie, while open to a share 
