Lyell talked to a local inhabitant and was told that the falls retreat about three feet a year. He assumed that this was an exaggerated claim and concluded that one foot a year would be a more likely figure (Lyell 1867, 1:361). On the basis of this guess, if was then a simple matter to equate 35,000 feet, or seven miles, as 35,000 years that the falls had taken to cut the gorge from the escarpment to the place if occupied in the year of his visit, which is how he arrived at the figure that he announced to the scientific world. The principle was sound enough, but his method can hardly be called scientific or even honest (Bailey 1962, 149).
In recent years the estimate bas been revised downward, but in the mid-nineteenth century it had a most significant impact on the common man's beliefs. Lyell's Principles of Geology, as already mentioned, was published in 1830-33, and although it was met with opposition at first, if eventually became the standard work on the subject for the next fifty years, running to twelve editions. Charles Lyell became Sir Charles in 1848, principally because of his Scottish landholdings. To the Victorian mind, this title gave his name and books tremendous credibility and authority; in a similar way today, the news media seek out a scientist with a legitimate Ph.D. when they want an authoritative scientific opinion. Lyell's figure of 35,000 years for the cutting of the Niagara gorge was thus accepted as an actual measurement made by a gentleman of integrity and quite beyond dispute. For the next few generations this estimate served wonderfully to demolish any credence in Archbishop Ussher's date of creation and made the attempt to finish once and for all the orthodox belief in the Mosaic Flood, which was alleged to have occurred a mere four-and-half thousand years ago.
Measurement of the rate of recession of Niagara Falls bas been made periodically since 1841, the date of Lyell's visit, and these published figures show that, far from exaggerating, the local inhabitant was too conservative. A rate of four or five feet a year is closer to the facts (Tovell 1979, 16). Assuming as Lyell did that the rate of recession had always been the same, this measured value reduces the age of the falls to between seven and nine thousand years. Had it been honestly reported in the first place, this would not have been regarded as a refutation but rather a near confirmation of the Mosaic Flood!
http://www.samizdat.qc.ca/cosmos/origin ... iagara.htm