THOMAS WRIGHT, F.S.A., The Celt, The Roman, and The Saxon,
ed. 1861.
...]
there is, nevertheless, reason to believe that it is, on the whole,
well founded. It is doubtless true that implements of stone continued
in use long after those of bronze and iron had been invented, arising
most probably from the dearness and scarcity of articles of metal;
but when the art of smelting and working in iron and steel had
sufficiently advanced, the use of stone, and afterwards of bronze
tools and weapons, altogether ceased.

The views of M. Worsaae, and the other Continental antiquarians who
follow his classification, have indeed received remarkable
confirmation of late years, by the discoveries which have been made
in the beds of most of the Swiss lakes.*
[footnote...
Referred to at length in the Antiquity of Man, by Sir C. Lyell, who
adopts M. Worsaae's classification.
...]
It appears that a subsidence took place in the waters of the Lake of
Zurich in the year 1854, laying bare considerable portions of its
bed. The adjoining proprietors proceeded to enclose the new land, and
began by erecting permanent dykes to prevent the return of the
waters. While carrying on the works, several rows of stakes were
exposed; and on digging down, the labourers turned up a number of
pieces of charred wood, stones blackened by fire, utensils, bones,
and other articles, showing that at some remote period, a number of
human beings had lived over the spot, in dwellings supported by
stakes driven into the bed of the lake.