Note 5 — Chapter IV

Almost every circumstance here mentioned, occurs in the salt lakes near the borders of the Caspian. That country, like Patagonia, appears to have been recently elevated above the waters of the sea. Pallas states that the salt lakes occupy shallow depressions in the steppes; that the mud on the borders in every case is black and fetid; that beneath the crust of sea salt, sulphate of magnesia occurs, imperfectly crystallized; that the muddy sand is mixed with lentils of gypsum. We have before stated that these lakes are inhabited by small crustaceous animals; and flamingoes (Edin. New Philos. Jour., Jan. 1830) likewise frequent them. As these circumstances, apparently so trifling, occur in two distant continents, we may feel sure they are the necessary results of some common cause.—See Pallas’s Travels, 1793 to 1794, p. 129-134.