A petrographic study of some eocambrian sedimentary rocks from the lake Mjøsa area, southern Norway, and the Tanafjord area, northern Norway.
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Grain size and composition were measured in about 50 samples from Eocambrian rocks near Lake Mjøsa and Tanafjord. The sparagmites in the Lake Mjøsa area vary widely in composition, but the average compositions of the formations are similar. The grain size distributions of the various formations are different, but consistent within each formation. Composition and grain size are treated statistically to evaluate differences among the samples. Grain size distribution does not appear to be a valid criterion for the correlation of the tillites studied. The Moelv tillite and the Tanafjord tillites show different patterns of grain size variability, suggesting that their modes of origin may have been different. Composition is related to grain size.