14 The American Geologist. July, 1894 
other theory of the causes of the [ce age is given, which makes 
it depend on high altitude of the glaciated regions, hut draws 
attention especially, like Lindvall, to the changes in the rela- 
tions of solar heat to the earth. This view, proposed by Dr. 
Blandet, and adopted by the Marquis de Saporta, Prof, de 
Lapparent, M. Falsan, and others, is presented in the follow- 
ing translation by Kendall in the ( i hx-ialists" 1 Magazine for 
January. 1K94: 
The sun musi certainly have passed through different stairs, and 
have produced at the surface of the earth various phenomena propor- 
tional to tin' magnitude of his successive diameters. With an apparent 
diameter of 47°, the distribution of lighl and heat, as M. de Lapparenl 
lias shown, would no longer correspond with the order of things estab- 
lished to-day. The differentiation of the seasons disappears, no part of 
the earth remains plunged in long nights, latitude loses a great part of 
its influence, the poles enjoy a mild temperature, and. at the torrid /.one, 
the nebular state of the sun attenuates and compensates for the excess 
of heal which would have resulted from its proximity to the earth.... 
These facts once admitted, and it would be difficult to gainsay 
them, many geological problems find their immediate solution. It is 
no longer a strange anomaly to see the rich vegetation which has grown 
about the pole in ancient geological epochs, and even till after the Mid- 
dle Tertiary times. One understands why, over all the earth and at all 
epochs, there succeeded a series of plants of which the uniform devel- 
opment was favored by the equability of climates and of seasons: how 
the plants have finished by disappearing from the poles, and by migrat- 
ing to the south, when the sun, always concentrating upon itself, could 
send them only feeble and oblique rays. Then the climate of the poles 
was slowly modified, the seasons were progressively accentuated, and 
t he atmospheric humidity was able to supply abundant precipitation 
of snow By the effect of solar concentration and of the changes 
operating in the mode of distribution of heat, the new climatic condi- 
tions resulted in a slate of unstable equilibrium; They could easily be 
modified by a host of circumstances previously of no effect, such as 
latitude, the variable action of marine and atmospheric currents, the 
orogenic movements of the earth, that is to say. the relief of mountains. 
These oscillations became stronger in proportion as the terrestrial crust 
acquired greater thickness, and they even acquired a preponderant in- 
fluence in the establishment of glacial conditions. 
A fourth theory, analogous with the three preceding, but 
more bold in its assumptions, disregarding many well ac- 
cepted conclusions of geology, as the continuous descent and 
development of floras and faunas, including those of the sea, 
and supposing ice-sheets to have extended over even inter- 
tropical land areas, has been thought out by Mr. Marsden 
