Geological Conclusions and Problems

Abstract

The division of fossil salt deposits according to the differences in their MgSO₄ content is a natural consequence of the clear distinction in their chemistry and petrography. All these types trace their origin back to the evaporation of seawater, for only in seawater is there the inexhaustible supply of Na, K and Mg etc. sufficient to account for the enrichment in salt deposits. In purely terrestrial salt lakes the precipitation of the chlorides of potassium and magnesium is scarcely ever attained and there is always a predominance of sodium and other carbonates or sulphates. The occurrence of borates and nitrates, on the evidence of the prevailing anions, is a clear indication of non-marine origin. The extent and salt content of terrestrial salt lakes is small (for details, see Lotze, 1938).