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occur when a shore line gives place to other records. For example: some of the ancient beach ridges about the west end of Lake Erie have been found to be continuations of moraines. In other instances shore ridges have been reported to end indefinitely and to be replaced at the same general horizon by glacial records of various character. The correct interpretation of phenomena of this nature is especially important.

Accurate measurements of the vertical intervals between well defined beaches at many localities would enable one to identify special horizons, providing orographic movements were not in progress during the time the series was forming. This method has recently been successfully applied on the north shore of Lake Superior, where the character of the country does not admit of the tracing of individual terraces for considerable distances.

The deltas of tributary streams should also be revealed in the topography of the basin of an ancient water body. Changes in the character of lacustral sediments near where rivers emptied are also te be looked for. Sand dunes are frequently an important accompaniment of existing shores, and their association, perhaps, in a modified form, with ancient beaches is to be expected.

5. Fossils. Thus far only a few fossils have been found in the stratified clays and sands or in the ancient beaches of the Laurentian basin. Such observations as have been made in this connection indicate an absence of the remains of marine life and the presence, in a few instances, of fresh-water shells in all of the basin west of the eastern border of the basin of Lake Ontario. To the eastward of Lake Ontario, however, in the St. Lawrence and Champlain valleys, marine fossils are common in deposits supposed to be contemporaneous with the stratified clays to the west.

A careful search in the clays and beaches left by the former water bodies might be rewarded by important discoveries. In this examination microscopical organisms should not be neglected. If after a detailed examination no fossils are dis-