The comprehensive Treatise of Geology has had its day. No man can hope any longer to assimilate and summarize the whole known geological history of the world. It has become almost a whole-time occupation to keep track of the literature of a single geological system.
This book represents the first attempt at a synthesis of one system on the basis of marine faunas in all parts of the world. Its object is twofold: first, to present a unified description as a reference work, and second, to enquire what can be deduced as to faunal realms, climate, palaeogeography, volcanic and plutonic activity and earth-movements, and especially the distribution of these in space and time, during one reasonably circumscribed period of geological history. The prerequisite of all such investigations is faunal correlation over the whole world, and no small part
of the object of this attempt has been to test the principles and performance of palaeontological correlation on the world scale, to establish its capabilities and limitations. <...>
