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, alluding 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 of the 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 generally ! 
For these plain reasons I demur to the extension of the ingenious reasoning of 
Mr. Croll 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 willingly 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 Herschel *, " 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 f, and of a drifted block of coal in the Chalk of Kent J, 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. Croll'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 allowed 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, " stability 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. xri. p. 326. 
