The Evolution of Herbaceous Plants and Its Bearing on Certain Problems of Geology and Climatology

Evidence from living and fossil plants has often proved of value in geological investigations. A large part of our information as to the climate of the various regions of the earth during ancient times, particularly in the Mesozoic and Tertiary, has been derived from a study of the plants composing the various fossil floras with reference to the climatic conditions under which their modern representatives live. A gradual differentiation and refrigeration of climate in the north and south temperate zones since the close of the Cretaceous have been pretty clearly indicated by such investigations.' Botanical evidence, particularly that derived from a study of the distribution of living and fossil plants, has also been of value to the student of ancient geography in providing support for such theories as that of a closer connection between North America and eastern Asia just before the Glacial period; a recent elevation of the coastal bench in eastern North America; and a more or less intimate union between Australia, New Zealand, and South America in recent times by means of an antarctic continent or archipelago.