| Summary: | The saline soils of the Slims River Delta have developed on land formed in the last 100 years in an area of otherwise continuous permafrost. Deep seasonal frost on the delta prevents downward leaching of salts when the snow melts. Instead the salts accumulate at the surface as the ground dries, while additional salts are added from springs at the base of the surrounding mountains. Late summer rains can leach the soils if they are sufficiently heavy, producing a three- to fourfold variation in salinity from year to year. The efflorescences are dominated by the hexahydrate of magnesium sulfate, and the high sulfate content is probably the reason that soils in depressions with the morphology of solonetzic soils remain reasonably friable. The distribution of the characteristic halophytic plant associations found on these soils appears to be controlled more by soil moisture content than by the actual salinity level.
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