Koko Rift

The Koko Rift formed on the southeast corner of the island of O‘ahu. A rift is generally a geological term for a long narrow zone of faulting resulting from tensional stress in the earth's crust. The name Koko is Hawaiian word for ‘blood’. Legend reports that a man was bitten by a shark in the Koko area. The Koko Rift has two segments: a 8.8 km long subaerial portion with seven major vents and numerous subsidiary vents, and a ~6 km long submarine ridge that extends along a trend parallel to the subaerial section but offset 0.5 km to the east. The subaerial section can be subdivided into a northern section that was characterized by effusive eruptions and a southern section with predominately explosive eruptions.

View on Mānana and Kāohikaipu islands from the Makapu'u Lookout

This cache offers you a unique opportunity to look at the northern end of the subaerial Koko Rift, which is made up of Mānana and Kāohikaipu islands. These islands were formed by subaerial flow fields that are now partially drowned by the ocean. These drowned flows would have been subaerial when erupted (~67 ka) because global sea level was ~100 m lower at that time than it is today.

The rocks in the vicinity of the cache (see the waypoint Lava field) are formed by Koko Rift lavas cooled in the form of ropes, which is referred to as pāhoehoe lava type. It is also interesting that the local basalts contain abundant green mineral known as olivine. This mineral forms a significant part of the Earth's upper mantle.

                   Pāhoehoe lava type                                                Olivine in basalt

Task

In order to log this cache, please upload a photo of you (or your personal item) at the lookout at given coordinates with the view to the Mānana and Kāohikaipu islands in the background. Logs without required photos will be deleted.

If you visited the site in a group, it is enough if only one of you uploads the photo. In this case, please mention nicks of the other geocachers that were with you.

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Virtual Rewards 3.0 - 2022-2023

This Virtual Cache is part of a limited release of Virtuals created between March 1, 2022 and March 1, 2023. Only 4,000 cache owners were given the opportunity to hide a Virtual Cache. Learn more about Virtual Rewards 3.0 on the Geocaching Blog.