442 T. V. Holmes—On Eskers or Kames. 
British eskers are most common in districts abounding with 
ordinary Glacial Drift, and appear to date from about the close of 
the Glacial Period. The evidence, as regards Cumberland at least, 
seems to me in favour of the supposition that at the close of that 
pericd the whole area was submerged, with the result of the con- 
version of much of the Till or Boulder-clay into gravel, usually 
more or less earthy. On the emergence of the district some of this 
earthy gravel was entirely removed, while the earthy matter was 
washed out of part of the rest, and the clean gravel and sand here 
and there heaped up into esker mounds and ridges; the positions of 
the latter at the time of their formation having been analogous to 
those of the various bars and sand banks now forming off our 
coasts. The distribution of eskers, and the presence of hollows 
without outlet in the midst of esker tracts, seem to me to be explain- 
able only on the supposition that eskers result from the irregular 
heaping up of material in shallow seas or estuaries from the action 
of diverse currents. Both Profs. A. H. Green! and James Geikie? 
remark that these curious hollows cannot possibly be due to the 
action of rain and rivers, and the late Prof. Beete Jukes? states that 
the outlines of esker mounds and ridges “are not due to mere denu- 
dation, but, as shown by the external structure of the mounds, have 
usually been produced at the same time as the mass of the sand and 
gravel was deposited.” Nevertheless an attempt was made by Mr. 
J. Durham (Guo. Mag. 1877, pp. 8-13) to show that though the 
materials of the Kames of Newport, Fife, are of marine origin, their 
shapes are due to rain and rivers, the sea having produced simply 
a plain of marine denudation. His explanation of the existence of 
the hollows without outlet in these Newport Kames is as follows :— 
“The pools are found in oval-shaped hollows, separated from each 
other, as well as from the drained areas, by comparatively trifling 
barriers; their oval hollows are the wider parts of the miniature 
valley of some vanished streamlet, while the barriers which block 
up their ends, and so form them into basins, are the narrower parts 
of the valley partially filled up by gravel washed down from its 
banks, the narrower parts being of course much more readily filled 
up than the wider.” It seems to me that this view of the production 
of the contours of an esker tract by the agency of rain and rivers 
may rank with that once commonly held of the marine origin of 
escarpments, as an equally instructive example of what invincible 
determination on behalf of a favourite agency can effect where zeal 
is untempered by discretion. I think the best answer that can be 
given to the rain and rivers view is a brief account of the eskers of 
a region strikingly different from Great Britain in physical geography 
and climate—the coast of Peru and Bolivia. 
For the following notes on the eskers of the western coast of 
South America I am indebted to my cousin Mr. J. J. Winder, who 
has resided many years in Peru and Bolivia, chiefly at Tupiza, in the 
1 Geology for Students, 2nd Edit. p. 472. 
2 Great Ice Age, p. 247. 
3 Manual of Geology, Jukes and Geikie, p. 710. 
