Black Sand - Lava Fragments

Lava Fragments

When lava contacts water, it cools rapidly and shatters into sand and fragmented debris of various size. Much of the debris is small enough to be considered sand. A large lava flow entering an ocean may produce enough lava fragments to build a new black sand beach almost over night. The famous "black sand" beaches of Hawaii, such as Punaluu Black Sand Beach, and Kehena Beach, were created virtually instantaneously by the violent interaction between hot lava and sea water. Since a black sand beach is made by a lava flow in a one time event, they tend to be rather short lived since sands do not get replenished if currents or storms wash sand into deeper water. For this reason, the state of Hawaii has made it illegal to remove black sand from its beaches. Further, a black sand beach is vulnerable to being inundated by future lava flows, as was the case for Hawaii's Kalapana beach, alternately known as Kaimu beach, or simply Black Sand Beach. Unlike with white sand beaches and Hawaii's green sand beach, walking barefoot on black sand can result in burns, as the black sand absorbs a great deal of the sun's energy.