CHAP. IX.] 
MILD ARCTIC CLIMATES. 
193 
that there has sometimes been a greater extension of the Antarctic 
lands during Tertiary times ; and it is therefore not improbable 
that a more or less glaciated condition may have been a long 
persistent feature of the southern hemisphere, due to the 
peculiar distribution of land and sea which favours the pro- 
duction of ice-fields and glaciers. And as we have seen that 
during the last three million years the excentricity has been 
almost always much higher than it is now, we should expect 
that the quantity of ice in the southern hemisphere will usually 
have been greater, and will thus have tended to increase the force 
of those oceanic currents which produce the mild climates of 
the northern hemisphere. 
Evidences of Climate in the Secondary and Palaeozoic epochs . — 
We have already seen, that so far back as the Cretaceous period 
there is the most conclusive evidence of the prevalence of a 
very mild climate not only in temperate but also in Arctic lands, 
while there is no proof whatever, or even any clear indication, 
of early glacial epochs at all comparable in extent and severity 
with that which has so recently occurred ; and we have seen 
reason to connect this state of things with a distribution of 
land and sea highly favourable to the transference of warm water 
from equatorial to polar latitudes. So far as we can judge by 
the plant-remains of our own country, the climate appears to 
have been almost tropical in the Lower Eocene period ; and as 
we go further back we find no clear indications of a higher, but 
often of a lower temperature, though always warmer or more 
equable than our present climate. The abundant corals and 
reptiles of the Oolite and Lias indicate equally tropical condi- 
tions ; but further back, in the Trias, the flora and fauna become 
poorer, and there is nothing incompatible with a climate no 
warmer than that of the Upper Miocene. This poverty is still 
more marked in the Permian formation, and it is here that 
clear indications of ice-action are found in the Lower Permian 
conglomerates of the west of England. These beds contain 
abundant fragments of various rocks, often angular and some- 
times weighing half a ton, while others are partially rounded, 
and have polished and striated surfaces, just like the stones of 
the " till.” They lie confusedly bedded in a red unstratified marl, 
o 
