For each of 5 groups of tree stumps and fallen trunks found well preserved on sites submerged at some unknown time by change in sea level with respect to the land, complete cross sections were made of all intact trunks. The sites were found along the coast of New England and Nova Scotia. The trees, identified from the wood, were chiefly white pine and hemlock, with some specimens of beech, birch, maple, oak, spruce, fir balsam and Pinus rigida. Graphs of mean ring widths of the pine and hemlock sections showed cross-dating in only a few cases. Since such graphs of contemporaneous trees can be matched readily, this study of trees killed by ocean water indicates that the submergence of the forests was so gradual that the individual trees either did not live at the same time or their growth periods overlapped for too short a time to be cross-dated.