148 Notes on the Geological Position of the Human Skeleton.
The finding of a tobacco-pipe 12 ft. below the surface shows
us how poor a measure of age is afforded by mere depth,
unchecked by other evidence, in the case of remain's found in
recent alluvial deposits. Engineers have estimated the growth
in thickness of the inundation-mud of the Nile as being at the
rate of five inches in a century. Consequently an article
found in it at a depth of 12 ft. might be fairly supposed to be
more than 2800 years old; while remains that have been
deposited in a former channel of a river given to frequent
changes of its course might be found at more than twice that
depth without having any necessary claim to be considered
ancient, even in the sense in which we speak of ancient
history.