444 T. V. Holmes—On Eskers or Kames. 
riding to traverse between places at which water may be obtained. 
Besides it is absolutely necessary to keep to the road or track, for if 
you leave it progression speedily becomes impossible. The un- 
disturbed ground is covered by a dry salt scum, chiefly consisting 
of nitrate of sodium, which breaks with the weight of a mule and 
allows her to plunge almost up to her girths in soft sand and 
shingle.” ‘These eskers are visible a few miles from Miscanti, a 
post house on the river Loa, which turns to the north-west and forms 
the boundary between Peru and Bolivia. Near Miscanti the country 
becomes considerably changed, for though the desert of Atacama 
extends many leagues eastward, the road at Miscanti is on lava- 
covered ground, through which the river runs in a narrow trough 
with perpendicular banks. It is always full to the brim, and very 
deep and dangerous. A little vegetation may be seen on its banks, 
the result of the moisture arising from the evaporation of the water. 
The long strip of country called the desert of Atacama is every- 
where composed of sand and shingle with a crust of nitrate of 
sodium (Na NO,) on the top. Much more nitrate of sodium—and 
in some places borax—is usually discovered on digging. The 
wonderful dryness of the air, and the entire absence of rain since 
the elevation of this tract of country above the level of the sea, 
could not be better attested than by the general diffusion of this 
substance, which is deliquescent in moist air and dissolves readily in 
water. There can thus be no doubt that these South American 
eskers owe their shape and distribution entirely to marine action, 
excepting only the slight modifications of form that have been caused 
by the southerly winds. 
The similarity between the eskers of these rainy British Isles and 
those of the rainless coast of Peru, in almost every respect, clearly 
points out that the influence of rain and rivers has had nothing to do 
with the formation of either, and has modified their present shapes 
only in the slightest degree. Indeed, the chief difference between 
the British and Peruvian eskers appears to consist in the grassy 
covering given by our moist climate to ours, and its absence from 
those of Peru. It may possibly be thought by some persons that 
the evidence brought forward with regard to British eskers suffi- 
ciently testifies to their marine origin apart from the Peruvian 
testimony to the same effect. But the paper on the Kames of New- 
port from which I have quoted shows that geologists are by no 
means unanimous on this point. And it is worth notice that the 
only opposition to Mr. Durham’s view, in the Gro. Mac., came 
from Mr. D. Mackintosh, whose remarks,’ though sound and to the 
point, would be considered by many readers to come from a some- 
what extreme believer in marine as compared with subaerial in- 
fluences, and consequently not receive the attention they deserved. 
Most of us remember the time when our President, Mr. Whitaker, 
became one of the chief champions of the power of rain and rivers 
to form escarpments, against certain geologists of more or less 
eminence who believed, “not wisely but too well,” in the denuding 
1 Grou. Mac. 1877, p. 94. 
