er Erde" (Prag and Leipzig, 1885). Suess
believes that "the local invasions and transgressions of the continental
areas by the sea" are due to "secular movements of the hydrosphere
itself." (See J. Geikie, F.R.S., Presidential Address before Section E
at the Edinburgh Meeting of the British Association, "Annual Report,"
page 794.) I suppose that there can be no doubt that when there was much
ice piled up in the Arctic regions the sea would be attracted to them,
and the land on the temperate regions would thus appear to have risen.
There would also be some lowering of the sea by evaporation and the
fixing of the water as ice near the Pole.

I shall read your paper with much interest when published.

LETTER 514. TO J. GEIKIE. Down, December 13th, 1880.

You must allow me the pleasure of thanking you for the great interest
with which I have read your "Prehistoric Europe." (514/1. "Prehistoric
Europe: a Geological Sketch," London, 1881.) Nothing has struck me more
than the accumulated evidence of interglacial periods, and assuredly
the establishment of such periods is of paramount importance for
understanding all the later changes of the earth's surface. Reading
your book has brought vividly before my mind the state of knowledge, or
rather ignorance, half a century ago, when all superficial matter was
classed as diluvium, and not considered worthy of the attention of a
geologist. If you can spare the time (though I ask out of mere idle
curiosity) I should like to hear what you think of Mr. Mackintosh's
paper, illustrated by a little map with lines showing the courses or
sources of the erratic boulders over the midland counties of England.
(514/2. "Results of a Systematic Survey, in 1878, of the Directions and
Limits of Dispersion, Mode of Occurrence, and Relation to Drift-Deposits
of the Erratic Blocks or Boulders of the West of England and East of
Wales, including a Revision of Many Years' Previous Observations," D.
Mackintosh, "Quart. Journ. Geol. Soc." Volume XXXV., page 425, 1879.) It
is a little suspicious their ending rather abruptly near Wolverhampton,
yet I must think that they were transported by floating ice. Fifty years
ago I knew Shropshire well, and cannot remember anything like till, but
abundance of gravel and sand beds, with recent marine shells. A great
boulder (514/3. Mackintosh alludes (loc. cit., page 442) to felstone
boulders around Ashley Heath, the highest ground between the Pennine and
Welsh Hill