178 
drift almost up to the equator. He says, Now that I 
have seen the whole length of the Straits of Magellan, have 
passed through Smithes Channel, and visited Chiloe, I am 
prepared to maintain that the whole southern extremity of 
the American continent has been uniformly moulded by a 
continuous sheet of ice ; everywhere we saw the rounded un- 
dulating forms so well known to the student of glacial phe- 
nomena as roches moutonnes. In Smith’s Channel there is no 
possibility of mistaking the evidence.”* 
22. Madame Agassiz, who accompanied her husband in his 
journey in Brazil, says that ‘^at 8° south of the equator he. 
Professor Agassiz, found undoubted moraines blocking up the 
valleys ; and the evidence of glacial action was, to him, as 
clear as in the valleys of Switzerland, of Scotland, and of the 
northern states of America.”! 
23. And in Central Chili Mr. Darwin found, in one of the 
valleys of the Andes, a mound of detritus 800 feet in height, 
which he was afterwards convinced was an ancient glacial 
moraine; he also spoke of evidence of former glaciers on the 
sides of the Cordillera at the very equator. J 
24. And Agassiz concluded a lecture at the Cooper’s 
Institute, New York, shortly before his lamented decease, 
saying, The ice covered the sea to such an extent that it is a 
question whether any open water was left at the equator theu, 
as it is a question whether there now is open water at the 
pole ; and, if this be so,” he says, you see at once how this 
intense cold must have modified the surface of the globe to 
the extent of excluding all life from the siirt‘ace.”§ 
25. The evidence before us is that of geologists, and of some 
of the highest authorities in geological science. There exists, 
as is seen, a difierence of opinion about how much of the 
devastation was the work of an ice-sheet, of enormous local 
glaciers, or that of submergence beneath an icy sea. The evi- 
dence appears to point to all these causes being in operation in 
different periods of the Glacial epoch. I may also notice the 
growing acceptance of the hypothesis of a Pluvial period im- 
mediately following the Glacial period, during which time 
Mr. Alfred Tyler (the propounder of the hypothesis) calculates 
a rainfall of 125 times that of the present, which filled some 
of the valleys and rivers with a thousand times their present 
volume of water, and, as a consequence, deluged the lower lands. 
* Letter to Professor Pierce, copied into Nature, July and August, 1872. 
t A Jonriieii in Brazil, by Madame Agassiz, p. 456. 
! Origin, of Species, first edition, p. 373. 
^ New Yorl' Tribune December 30tli, 1873, 
