After some differences in concept, the term climate has come to be applied to the atmospheric conditions of weather normal to a given locality or region. Although there are very considerable areas of the earth’s surface that exhibit similar climatic conditions, it needs little reflection to demonstrate that the climate of the earth at the present day is by no means uniform throughout. If, for instance, we travel either north or south from the equator we pass successively through a so-called torrid zone, a temperate zone, and, in polar lands, a frigid zone, each with minor but distinctive modifications. In other words, the present distribution of climate is zonal. But it has been demonstrated with what seems a reasonable degree of certainty that the climates of the past were distinctly non-zonal in their distribution—that is, ancient climates appear to have been practically uniform for vast periods of time and . . .