Post-glacial sediments at a site near Earl Grey, Saskatchewan, contain ten species of ostracods and five species of molluscs, which provide information on the climatic history of the site since the last recession of the Wisconsin glacier. The base of a layer of organic sediments, 5.8 meters below the surface, contains wood which was radio-carbon dated at 10,275 ± 225 years B.P., a minimum date of the last deglaciation of the Earl Grey site.

Environmental changes are reflected by breaks in the stratigraphic continuity and in the abundance of ostracod and molluscan species. The fauna and the physiography of the area surrounding the site suggest that the environment was always that of a small lake or pond which was relatively deeper and more permanent during the earlier part of its history than it is now. Pollen and spore studies indicate the presence of spruce-pine parkland with a later appearance of alder and oak, which gradually gave way to a predominantly grass flora as the ice margin receeded further northward. A diastem which occurred during the middle of the Earl Grey stratigaphic section probably represents the middle of the Hypsithermal interval.

A statistical study of the ostracod shells reveals some information as to the ontogenetic history of fresh-water ostracods. Most of the ostraocods at the Earl Grey site tend to have 6-9 molt stages during ontogeny. Cypris pubera, the largest species found at the site, has as many as 9 molt stages.

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