<p>Fig. 1.&nbsp;Salt rings formed by evaporation of seawater on watch glass. The blue ring is the outermost, least soluble salt. The orange salt ring is the most soluble salt.</p>

Fig. 1. Salt rings formed by evaporation of seawater on watch glass. The blue ring is the outermost, least soluble salt. The orange salt ring is the most soluble salt.

Image by Joanna Philippoff and Brittany Supnet