If there are not rivers flowing out of the lake (see Endorheic basin), or they are few and small, the lake loses water only by evaporation or because the water flows through the soil pores. Where the water evaporates rapidly and the soil around the lake has a high salt level, as in very dry places, the water of the lake has a high concentration of salt and the lake is called a salt lake. Examples of salt lakes are the Great Salt Lake, the Caspian Sea, the Aral Sea, and the Dead Sea.