Note 43 — THE TESTIMONY OF THE ROCKS. (continued 7)

Sir Charles Lyell's statement is by no means so express or definite as it is represented to be in this passage, in which I have taken the evidence of his opponents regarding it. What he really says (see his "Principles," second edition, 1832) is what follows:—"If the ratio of recession had never exceeded fifty yards in forty years, it must have required nearly ten thousand years for the excavation of the whole ravine; but no probable conjecture can be offered as to the quantity of time consumed in such an operation, because the retrograde movement may have been much more rapid when the whole current was confined within a space not exceeding a fourth or fifth of that which the Falls now occupy." In the eighth edition of the same work, however, published in 1850, after he had examined the Falls, there occurs the following re-statement of the case:—"After the most careful inquiries I was able to make during my visit to the spot in 1841–42, I came to the conclusion that the average [recession] of one foot a year would be a much more probable conjecture than that of one and a quarter yards. In that case it would have required thirty-five thousand years for the retreat of the Falls from the escarpment of Queenston to their present site. It seems by no means improbable that such a result would be no exaggeration of the truth, although we cannot assume that the retrograde movement has been uniform. At some points it may have receded much faster than at present; but in general its progress was probably slower, because the cataract, when it began to recede, must have been nearly twice its present height."