The water in this sea evaporated, leaving behind a bed of mineral-rich bentonite clay.
It can also be used as a facial. The gel can be applied externally as a poultice on cuts, bruises, insect bites, bee stings, boils, rashes, acne and burns. For external use - Mix the clay with water to make a gel about the consistency of mustard. Many years ago, long before the earth knew pollutants of any kind, a range of volcanoes erupted - sending volcanic ash into the water of the ancient Sundance Sea that covered much of North America.