If the Laurentian basin was occupied by an arm of the sea during various stages in the Pleistocene elevation, then the records of such a submergence should occur both within and without the depression, and direct connection between the two should be expected. If the waters within the basin were capable of making such well-defined shore records as are now found, we are justified in assuming that the true ocean beach on the outer slopes of the basin would be still more conspicuous. Again, the waters within the basin deposited a sheet of sediment, certainly not less than one hundred feet thick; to be sure the conditions for rapid accumulation were there present, but if the ocean covered the adjacent land it should have left similar deposits. This is abundantly proven in the St. Lawrence and Champlain valleys, where clays containing marine fossils occur up to a certain horizon and record a Pleistocene invasion of these depressions by the sea. If the adjacent Ontario basin was occupied by the sea about the same time that the Champlain valley received its filling of clays containing marine fossils, there is every reason to believe that the deposits and their contained fossils in each basin would have been essentially the same. One of the best known of the ancient shore lines about Lake Ontario has an average elevation of approximately 500 feet above the sea. If the sea had access to the basin at the time this breech was formed, then at corresponding horizon without the basin especially, to the south and southeast, where the full force of the Atlantic’s waves would have been felt, there should be still more prominent beaches. Many well-defined shore lines in the Laurentian basin are much higher than the one just referred to, and if these were also formed during various stages of submergence, as has been claimed, it is evident that ocean beaches and ocean sediments of Pleistocene age should be looked for over nearly the whole of the eastern part of the United States. The student may easily answer this question for himself, and thus perhaps make a contribution to the subject here treated. In the investigation here outlined, the work of previous observers should not be ignored, and every plausible hypothesis that has been advanced to account for the facts observed should be carefully tested. In writing these pages I have not quoted the writing of others, for the reason that a discussion of evidence has not been the aim in view, and also because the writings examined are so numerous that justice could not be done them in the space at command. That the literature relating to the subject is voluminous is indicated by the fact that an annotated bibliography of the Pleistocene history of the Laurentian basin, now in preparation, already contains over 200 entries of individual papers. ISRAEL C. RUSSELL. FOOTNOTES