A year ago the Paleontological and the Geological Societies united in a symposium on The Close of Cretaceous and Opening of Eocene Time in North America. That symposium brought out very clearly the wide differences of opinion and practice now prevailing among American geologists and paleontologists as to the kinds of evidence on which we must chiefly rely in geologic and paleontologic correlation, chiefly as to the relative criteria of earth movements and of paleontology.
We are now met to discuss the characteristic features of another important period of geologic time, namely, the Jurassic-Cretaceous limits, as they have been defined in Europe from which, it can not be too strongly stated, we must take all our geologic time standards and demarkations. In this connection I would like to repeat the main statement in my address last year: “American events can be dated only by . . .