BY R. M. JOHNSTON, F.LS. 103. 
EVIDENCES oF GREAT GuAcIAL Hrocus CoNncURRING WITH 
Great CycLiEs oF CHANGE IN OrGANIC LIFE, AND 
ALSO CONCURRENTLY WITH EXCEPTIONAL TERRESTRIAL 
DisTURBANCES. 
The adoption of the astronomical theory as the sole cause 
of glacial epochs throughout all time naturally excited a pre- 
judice against it in the minds of many able geologists, because 
the known records of the rocks, with the exception of, per- 
haps, the last two great cold epochs—viz., “The glacier 
epoch of Australasia,’ at the beginning of the Pliocene 
(Neogene of Tasmania), and the ‘ice age” of Hurope and 
North America, in Pleistocene age—there is not the feeblest 
evidence of glacial phenomena intercalated within the sedi- 
mentary formations, even going as far back as the close of 
Permo-Carboniferous times. This utter lack of correspondence 
with the frequent recurrences of periods of maximum eccen- 
tricity of the earth’s orbit with winter in aphelionin any one 
hemisphere every 21,000 years, through all this time, certainly 
appeared to demonstrate that the astronomical theory alone 
could not adequately account for the facts. 
The “imperfection of the record’’ theory of effacement 
which was sought by Sir Robt. Ball and others to form a 
buttress to it, breaks down completely when closely and 
widely inquired into. But perhaps the greatest blow to the 
“imperfection of the record” theory of effacement in attempt- 
ing to show harmonious reasons for the total absence of glacial 
phenomena in the tertiary rocks generally—in Europe at 
least— corresponding to recurring cycles of eccentricity, is the 
discovery of glacial phenomena, consisting of vast beds of 
striated conglomerates, polished rocks, perfect roches- 
moutonneés, and huge ice-borne erratics in the rocks of Permo- 
Carboniferous age, of nearly all countries in both hemi- 
spheres; and thus even showing a greater universality of 
broadly contemporaneous intense glacial conditions than 
was exhibited during the last “ice age” of Europe 
and North America in the Pleistocene period. For, 
surely, if obliteration by denudation, carried on over a 
long period, was considered to be an adequate reason for the 
removal of all traces of glacial action in the earlier Tertiary 
rocks of Europe, the actual preservation, universally of abun- 
dant and undoubted glacial phenomena in the much more 
remote Permo-Carboniferous rocks, during such a vastly 
greater period of time, utterly collapses the “ imperfection of 
the record”’ theory of effacement, as applied to the secondary 
and tertiary rocks. 
The older glacial epoch of Permo-Carboniferous age, together 
