52 REV. PROF. G. F. WRIGHT, ON THE INFLUENCE OF THE 
years ago, and, therefore, that the acceptance of this view 
involved an enormous antiquity for the human race. At 
that time Lyell’s uniformitarian theory concerning geological 
movements was scarcely questioned by any, and it was deemed 
legitimate for geologists to make unlimited demands upon the 
Bank of Time. An interesting illustration of this is found in 
the calculation made by Charles Darwin in the first edition of 
his Origin of Species,* where he estimated that a limited amount 
of erosion of the geological deposits in southern England must 
have occupied over 306 million years, which he says is a “ mere 
trifle ” of geologic time. Indeed, the uniformitarians generally 
regarded such a period as 500,000,000 years as a convenient 
thing to conjure with, while Sir Andrew Bamsay and othersf 
maintained that for all we could tell geologic time was 
absolutely limitless. 
But since the publication of the first edition of The Origin 
of Species and of Lyell’s Antiquity of Man there has been a 
startling revolution in the opinion of scientific men concerning 
the age of the world and the length of geologic periods. In 
the later editions of The Origin of Species the calculation above 
referred to has been omitted and a paragraph inserted in its 
place, making some very pertinent remarks about the inadequate 
conception which most men have of the significance of even 
one million years and of the changes which would take place 
during that period, even at a very slow rate. Sir Archibald 
Geikie emphasises the point by calling attention to the fact that 
if a river lowers its bed by erosion one foot in one thousand years 
(which certainly is a very slow rate) it would produce a gorge 
1,000 feet in depth in one million years. Such rivers as the 
Colorado in America are entirely competent to have eroded a 
canon 6,000 feet in depth in one million years. Indeed on 
every hand evidence is multiplying of the great activity of the 
forces which produce changes in the earth’s surface and in the 
species of animals and plants which live upon it. 
It was Professor George H. Darwin who first demonstrated 
to the satisfaction of his fellow mathematicians that the moon 
was thrown off from the world not more than one hundred 
million years ago, and therefore, that the geological ages whose 
history is studied in the stratified rocks of the earth must be 
compressed within that period. Later, Lord Kelvin has voiced 
the pretty general belief of his associates in maintaining that 
* See pp. 250-252. 
t See Lord Kelvin’s Annual Address at the Victoria Institute, 1897. 
