177 
F.G.S., in tlie Quarterly Journal of Science, October^, 187 I , 
says, The glacial systems had reached, in the tropics, at least 
as far as Nicaragua, where, within thirteen degrees of the 
equator, I found undoubted traces of glacial action to 
2,000 feet above the sea level where snow now never falls/^ 
20. The same author, in his Nainralist of Nicaragua, relates 
a journey from San Eafael (only about eight degrees from the 
equator), and says that boulder clay extended the whole 
distance of the journey, and that ranges of hills appeared to 
be composed entirely of it. I was unprepared,^^ he says, 
at the time to believe that the Glacial period could have left 
such memorials of its existence within the tropics, at not 
greater elevation above the sea than 3,000 feet.’^* Equally 
unprepared was Mr. Alfred Kussell Wallace to suppose that 
he had found an erratic more than 20 feet in diameter within 
less than half a degree of the equator. It was on a slight 
eminence, and so perched, that its being deposited there by a 
grounded iceberg is the only explanation that he can offer. It 
was not until further evidence was afforded of glacial action 
in the valley of the Amazons that he could be satisfied with 
his own explanation. (Compare “ Travels on the Amazon, 
p. 219, with ^^Ice Marks in North Wales,^^ Quarterly Journal 
of Science^ January, 1867.) Mr. Alfred Wallace and M. Louis 
Agassiz were at the antipodes on the question of evolution, 
but were at one on the evidence of ice action at the equator. 
And Mr. Alfred Tylor, who has written upon the evidence 
and cause of changes in the sea-level during the Glacial period, 
has, in this room, expressed his belief in signs of glaciation in 
equatorial Africa.f 
21. Nor is the evidence of the Glacial period confined to the 
Northern Hemisphere, for at about the same degree south of 
the equator that the British Isles are north, both Mr. Alfred 
Wallace and Mr. Charles Darwin found evidence of its former 
existence. At Tierra del Fuego and at Patagonia glacial drift 
is found at elevations of 1,400 feet, about the same height 
as it is found at Wexford. Mr. Charles Darwin quotes the 
evidence of Dr. J. Haast and Dr. Hector in proof of former 
glaciers at a low level in New Zealand, whilst, from facts com- 
municated to him by the Rev. W. B. Clarke, he is satisfied 
that there are traces of the same conditions in the south-east 
of Australia ; whilst Agassiz, in his travels in Brazil, and in 
the valley of the Amazons, traces the phenomena of glacial 
* Naturalist in Nicaragua, pp. 247, 248, 273, 274. 
t Transactions of Victoria Institute, Vol. x. p. 29. 
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