Glass Beach, Hawaii

October 07, 2010

Photographer: Thomas McGuire
Summary Author: Thomas McGuire

Beaches are composed of a wide variety of materials from large rocks to tiny clay particles. First to come to mind are sandy beaches that range from the nearly pure white beaches on the Gulf of Mexico near Panama City Beach and Pensacola, Florida to the black, basalt shatter-sand beaches of the Big Island of Hawaii. Many ocean beaches from the Carolinas into the Gulf of Mexico are composed of the remains of sea shells. Large boulders transported by continental glaciers are prominent on some New England beaches. New York’s Finger Lakes have many beaches composed of flat disk-shaped pieces shale.

The ocean shoreline is a very dynamic environment. Wave action wears down beach materials as it pounds particles upon particles and reduces them in size. It also makes the particles more rounded. Even shards of broken glass eventually become rounded and frosted as they are transformed by wave abrasion into “beach glass". The unusual beach featured above at Hanapepe on the island of Kauai (Hawaii) is a former disposal site where glass bottles were discarded for many years. Although the local rock is basalt (visible on the right), the beach is largely composed of weathered pieces of glass that have been broken and rounded by the pounding surf. The various colors of glass can be seen in the insert at the top-left. Instead of buying souvenirs, some people collect sand and beach materials to document their travels. Samples can be organized and even displayed in transparent containers. On what different attributes might you classify your samples? Photo taken on September 12, 2010.