Occurrence and geochemistry of lake-bottom manganiferous deposits in Canadian lakes

It is the purpose of this paper to record information concerning the distribution and occurrence of manganiferous concretions and other manganese oxide deposits that develop on certain lake bottoms. During the summer of 1935 several days were devoted to a study of this type of lake bottom deposit in various parts of Nova Scotia. Lake studies in Ontario have extended the known distribution from lakes on or near the Atlantic coast to lakes in southern Ontario. During the writer's first work on lacustrine manganiferous deposits the concretions of manganese oxide which were found were almost entirely limited to the relatively shallow parts of the lakes examined. Other lakes are now known where the manganese oxide appears to occur only in the maximum depths.

(Table, page 500) Geochemistry of a pancake-shaped concretion from lake Charlotte, Canada

A pancake-shaped concretion from Ship Harbour Lake, a small freshwater lake in eastern Nova Scotia (now named Lake Charlotte) is part of collection sent to the National Museum of Canada by Mr. R. A. Logan, of the Pan American Airvays. These concretions are of similar to the well-known marine concretions with a composition similar to wad. These are known only from abyssmal depths of the sea in the red clay deposits, while the present concretions occur in very shallow lake waters. They should be of interest to geologists, who may be concerned with the rather difficult problem which some concretions raise of distinguishing between concretions of syngenitic and epigenetic origin.