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1905-6.] Is BELIEF IN A GLACIAL PERIOD JUSTIFIED? 
IS BELIEF IN A GLACIAL PERIOD JUSTIFIED? 
By Henry DE Q. SEWELL, Assoc. M. Insrt., C.E., 
(Read 21st April, 1906.) 
Is the belief in a Glacial Epoch justified? is a question that may 
well be asked by thinking geologists, sixty-six years after it was first 
promulgated by Agassiz, who in 1840 wrote that, ‘‘If the analogy of the 
facts he had observed in Scotland, Ireland and the North of England, 
with those of Switzerland be correct, it must be admitted that not only 
glaciers once existed in the British Isles, but that large sheets of ice covered 
all the surface.’’ He also urged ‘‘that glaciers did not descend from the 
mountain summits into the plains, but that they were the remaining por- 
tions of sheets of ice, which at one time covered the flat country.” ‘‘It 
is evident,’ he says, ‘‘that if they descended from high mountains and 
extended into the plains, the largest moraines ought to be the most dis- 
tant, and to be formed of the most rounded masses, whereas the actual con- 
dition of the detrital accumulations is the reverse, the distant materials 
being widely spread and true moraines being found only in the valleys con- 
nected with great chains of lofty mountains.’’ He, however,admitted that 
he had never seen till until he visited Scotland and Mr. J.Geikie says, ‘‘We 
cannot fail to remark that although scratched and polished stones occur 
not unfrequently in the frontal moraines of Alpine glaciers, these moraines 
do not at all resemble till or boulder clay. The moraine consists for 
the most part of a confused heap of rough angular stones and blocks and 
loose sand and débris, scratched stones are decidedly in a minority, indeed 
a close search will often fail to find them. Clearly then till is not of the 
nature of a terminal moraine.’’ And again he says, ‘‘We look in vain 
among the glaciers of the Alps for such a deposit as till; the scratched 
stones we may occasionally find, but where is the clay? Thus at the 
very outset the theory which Agassiz based on a supposed analogy be- 
tween the British Isles and Switzerland, is shown never to have existed, 
that true moraines are only to be found in valleys connected with lofty 
mountains, also that moraines are not of the nature of till. So we may well 
ask with Prof. Young that since fifty to sixty per cent. of till consists of 
impalpable mud, why was it not washed away by the waters constantly 
present beneath moving ice? Again Agassiz postulates that not only the 
Baltic Sea, but the German Ocean, also was bridged across by ice, on 
which many boulders were transported from Scandinavia and that this 
