190 The Americmi Geologist. sei)temi)er, 1892 
We were taught by our great and honored master, Lyell, to believe Im- 
plicitly in gentle and uniform operations, extended over indefinite pe- 
riods of time, though possibly some with the zeal of partisans carried this 
belief to an extreme which Lyell himself did not approve. What the 
more extreme members of the uniformitarian school failed to perceive 
was the absence of all evidence that terrestrial catastrophes, even on a 
collossal scale, might not be a part of the present economy of this globe. 
Yet the admission that they have played a part in geological history 
may be freely made without impairing the real value of the Huttonian 
doctrine." 
The speaker then quoted the Ice-Age as a strong case in point of the 
truth of his remark. "If," he said, "any one had ventured sixty years 
ago to affirm that at no very distant date the snows and glaciers of the 
Arctic regions had descended southwards into France, he would have 
been treated as a visionary theorist. There cannot, however, be any 
doubt that after man had become a denizen of the earth a great physical 
change came over the northern hemisphere. The climate which had 
previously been so mild that evergreen trees flourished within ten or 
twelve degrees of the polf, became so severe that vast sheets of snow 
and ice covered the north of Europe and crept southward beyond the 
south coast of Ireland almost as far as the southern shore of England, 
and across the Baltic into France and Germany. Such a marvelous 
transformation in climate, in scenery, in vegetation and in inhabitants, 
within what was'after all a brief portion of geological time, is surely en- 
titled to rank as a catastrophe in the history of the globe. And yet it ar- 
rived manifestly as a part of the great order of nature. And thus taking 
a broad view of the whole subject, we recognize the catastrophe, while 
at the same time we see in its progress the operation of those same nat- 
ural causes which we kuow to be integral parts of the machinery where- 
by the surface of the earth is continually transformed." 
Passing on then to another doctrine first clearly and definitely stated by 
Hutton, Sir A. Geikie sketched the views that prevail regarding geological 
time. "Some 6,000 years had previously been believed to comprise the 
whole life of the planet, and indeed of the entire universe. But the 
progress of research continually furnished additional evidence of the 
enormous duration of the ages that preceded the coming of man, while, 
as knowledge increased, periods that were thought to have followed each 
other consecutively were found to have been separated by prolonged in- 
tervals. Thus the idea arose and gained universal acceptance, that just 
as no boundary could be set to the astronomer in his free range through 
space, so the whole of by-gone eternity lay open to the requirements of 
the geologist. It was Lord Kelvin who first called attention to the 
fundamentally erroneous nature of these conceptions. He pointed out 
that from the high internal temperature of our globe, increasing inward 
as it does, and from the rate of loss of its heat, a limit may be fixed to 
the planet's antiquity. He estimated that the surface of the globe could 
not have consolidated less than twenty million years ago nor more than 
four hundred million years ago, and he was inclined to believe that. 
