As these are many millions of years removed from each
other and from the Carboniferous, it is possible that they
represent earlier periods more or less corresponding to the
Permian. But the early chronicle is so compressed and so
imperfectly studied as yet that it is premature to discuss the
point. It is, moreover, unnecessary because we know of no life on
land in those remote periods, and it is only in connection with
life on land that we are interested in changes of climate here.
In other words, as far as the present study is concerned, we need
only regard the climate of the Devonian and Carboniferous
periods. As to this there is no dispute; nor, in fact, about the
climate from the Cambrian to the Permian.
As the new school is most brilliantly represented by Professor
Chamberlin,* it will be enough to quote him. He says of the
Cambrian that, apart from the glacial indications in its early
part, "the testimony of the fossils, wherever gathered, implies
nearly uniform climatic conditions . . . throughout all the earth
wherever records of the Cambrian period are preserved" (ii, 273).
Of the Ordovician he says: " All that is known of the life of
this era would seem to indicate that the climate was much more
uniform than now throughout the areas where the strata of the
period are known" (ii, 342).
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