APPENDIX.                                                549

Lyell. In his last concluding remarks on climate, and after showing that a
" warm, humid, and equable climate " must have prevailed in Palaeozoic times,
he, aUuding to the indications that have been'discovered of intervening glacial
action in the Miocene, Eocene, and Permian eras, makes this pertinent reflec¬
tion :—" but no decided changes in the character of the organic remains have yet
been shown to accompany the inorganic proofs of supposed glacial action of these
remoter periods."—Principles of Geology, 10th Ed. (1867), vol. i. p. 232.

Now, if so good an authority seems to doubt the validity of the evidence of
glacial action in the Eocene and Miocene eras, when the surface ofthe earth or
the relations of land and water had much approximated to their existing out¬
lines, how infinitely more must we demur to glacial action in the Primary ages,
when a warm, humid, and equable climate prevailed so generaUy !

For these plain reasons I demur to the extension of the ingenious reasoning of
Mr. CroU as founded upon the glacial phenomena of the Arctic and Antarctic
regions, and I submit that it cannot be applied to the enormous areas which
were under water or raised into moderately lofty lands in Palaeozoic times.

At the same time I wiUingly grant that there may be much force in his
reasoning when applied to regions within the influence of the poles. In short, I
bow to the opinion of Sir John Llerschel *, " that the very considerable extent
to which in immensely long periods the oscillation in the eccentricity and incli¬
nation of the ecliptic, combined with movement of the apsides, may affect our
climates, must be very influential upon the quantities of ice and extent of
glacial production."

Notwithstanding my scepticism as to the existence of glaciers and extensive
glacial action during any period anterior to Tertiary times, I think it right to
state that the examples of erratic blocks of granite and greenstone in the Chalk
of Croydon t, and of a diifted block of coal in the Chalk of Kent f, may be
rationally accounted for by the supposition that they were carried southwards
by shore-ice floating from the Arctic regions.

There is another part of Mr. CroU's paper which must sadly disturb the con¬
victions of geologists who have referred the presence of sea-beaches and marine
shells at different heights to successive elevation of shores and sea-bottoms.
He, on the contrary, is disposed to refer them to great periodical rises of the
sea-level, due to the melting of vast masses of ice. But such a cosmical theory,
however ingenious, cannot be aUowed to 'overbear geological induction based
upon numberless well-ascertained proofs of elevations of the land. In short, all
geologists, as far as I know, subscribe to the truth of the apparently paradoxical
aphorism of my old friend Greenough, " stabilitj'^ of the waves, mobility of the
land."

T.—The Silurian Passage-beds in Shropshire (pp. 139 &c.).

The details of a very interesting section of the Upper Silurian Passage-beds,
with the two Bone-beds in place, at Linley in Shropshire, were given by the
late Mr. G. E. Roberts and Mr. J. Randall in the Quart. Journ. Geol. Soc.
vol. xix. p. 229 ] and in the same volume, p. 233, Mr. Roberts described and illus¬
trated some tracks of Crustaceans or Fishes in the Passage-beds near Ludlow.

* Letter to myself, June 9, 1867.

t Quart. Journ. Geol. Soc. vol. xiv. p. 252.                              I Ibid. vol. xvi. p. 326.