Diamond Head, Oahu, Hawaii

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Diamond Head or Le’ahi

 

The volcanic tuff cone on the island of Oahu in Hawaii is called the Diamond Head. It is known to the locals as Le’ahi, which means “tuna” since the shape of the cone’s ridge line is reminiscent of a tuna’s dorsal fin. “Diamond Head” was a name given in the 19th century by British sailors who mistook for diamonds the calcite crystals embedded on the rocks.

Diamond Head makes up part of a complex of vents, cones and their eruption flows, which geologists

call the Honolulu Volcanic Series. The Honolulu Volcanic Series is also known as the chain of volcanic eruption events creating several of Oahu’s distinctive landmarks such as the Punchbowl Crater, the

Koko Head, the Hanauma Bay, the Manana Island, and, of course, the Diamond Head.

Like the other Honolulu Volcanoes, Diamond Head is younger than the main portion of the Koolau Mountain Range, which geologists estimate to be 2.6 million years old while the Diamond Head is believed to be only 200,00o years old. It has been inactive for the past 150,000 years.

Scientists believe that the eruption which created Diamond Head was brief and could not have lasted

for more than a few days since the cone is very symmetrical. The eruptions must have been very powerful and explosive, since sea level was higher before the cinder cone was formed.