1875,] The History of our Earth. 321 
60! Each hemisphere, he assumes, is in turn colder 
and warmer. The sea retires on the warm hemisphere, 
where the ice-cap is decreasing, and gains ground on the 
colder hemisphere, where ice is accumulating. In a period 
of 10,000 years the conditions are reversed, the reversal 
being not incidentally, but inevitably attended with a 
universal deluge. The last catastrophe of this kind was 
the Noachian flood, when the great ice-cap then existing 
on the North Pole collapsed, and the preponderating 
amount of water previously collected in the northern hemi- 
sphere rushed across the globe to its present position in the 
south. On this hypothesis the southern ice-cap will 
continue to increase for about another thousand years from 
the present date, whilst the southern hemisphere becomes 
still colder, and the sea gains ground upon the land. At 
the expiration of that time the process is reversed; the 
southern ice-cap begins to decrease, and its northern 
antagonist to preponderate. The maximum amount of 
water recedes from the southern hemisphere and encroaches 
upon the land in the north. Finally, when 10,000 years 
from the days of Noah have expired, and when the winter 
of the southern hemisphere approaches perihelion, ‘“‘ the 
ice grows soft and rotten from the accumulated heat, the 
sea begins to eat into the base of the cap, which is so 
undermined as to be left standing upon a kind of gigantic 
pedestal. This disintegrating process goes on till the fatal 
moment at length arrives, when the whole mass tumbles 
down into the sea in huge fragments, which become floating 
icebergs. The attraction of the opposite ice-cap, which 
has by this time nearly reached its maximum thickness, 
becomes now predominant. The earth’s centre of gravity 
suddenly crosses the plain of the Equator, dragging the 
ocean with it, and carrying death and destruction to every- 
thing on the surface of the globe.” 
We need scarcely say that this theory harmonises ill with 
positively established facts in physics, climatology, geology, 
and animal geography. We have no evidence that all land 
animals and plants have been periodically eradicated every 
10,000 years. We have proof—almost, if not quite, absolute 
—that certain parts of the earth’s surface at no extra- 
ordinary altitude, have not been submerged for a length of 
time greater than this theory would imply. We have good 
evidence that the polar caps rest, not upon the bottom of 
the sea, but upon land, and we consider that in the former 
case the probability of their melting away and breaking up 
would be but slender. In short, this theory may be held up 
