s and gravels."
The immense antiquity of the human remains in the gravels of the Pacific
coast is summed up by a most eminent English authority and declared
to be proved, "first, by the present river systems being of subsequent
date, sometimes cutting through them and their superincumbent lava-cap
to a depth of two thousand feet; secondly, by the great denudation that
has taken place since they were deposited, for they sometimes lie on the
summits of mountains six thousand feet high; thirdly, by the fact that
the Sierra Nevada has been partly elevated since their formation."(187)

(187) For the general subject of investigations in British prehistoric
remains, see especially Boyd Dawkins, Early Man in Britain and his Place
in the Tertiary Period, London, 1880. For Boucher de Perthes's account
of his discovery of the human jaw at Moulin Quignon, see his Antiquites
Celtiques et Antediluviennes, vol. iii, p. 542 et seq., Appendix. For an
excellent account of special investigations in the high terraces above
the Thames, see J. Allen Brown, F. G. S., Palaeolithic Man in Northwest
Middlesex, London, 1887. For discoveries in America, and the citations
regarding them, see Wright, the Ice Age in North America, New York,
1889, chap. xxi. Very remarkable examples of these specimens from
the drift at Trenton may be seen in Prof. Abbott's collections at the
University of Pennsylvania. For an admirable statement, see Prof. Henry
W. Haynes, in Wright, as above. For proofs of the vast antiquity of man
upon the Pacific coast, cited in the text, see Skertchley, F. G. S., in
the Journal of the Anthropological Institute for 1887, p. 336; see also
Wallace, Darwinism, London, 1890, chap. xv; and for a striking summary
of the evidence that man lived before the last submergence of Britain,
see Brown, Palaeolithic Man in Northwest Middlesex, as above cited.
For proofs that man existed in a period when the streams were flowing
hundreds of feet above their present level, see ibid., p. 33. As to the
evidence of the action of the sea and of glacial action in the Welsh
bone caves after the remains of extinct animals and weapons of human
workmanship had been deposited, see ibid., p. 198. For a good statement
of the slowness of the submergance and emergence of Great Britain, with
an illustration from the rising of the shore of Finland, see ibid.,
pp. 47, 48. As to the flint implements of Palaeolithic man in the high
terraced gravels throughout th