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Glaciers Existed on Mauna Kea During Recent Ice Ages

Glacial deposits of the Waihu Glacial Member exposed in unnamed gulch on southwest flank of Mauna Kea at about 3,020 m (9,900 ft) elevation. Ages of both the glacial deposits and lava flows are poorly known, estimated to within about 150,000 to 70,000 years ago. Pole is 1.5 m (5 ft) long. (Public domain.)

Most people don't think about snow or glaciers in Hawai‘i, but geologists have long recognized deposits formed by glaciers on Mauna Kea during recent ice ages. The latest work indicates that deposits of three glacial episodes since 150,000 to 200,000 years ago are preserved on the volcano. Glacial moraines on the volcano formed about 70,000 years ago and from approximately 40,000 to 13,000 years ago. If glacial deposits were formed on Mauna Loa, they have long since been buried by younger lava flows.

 

Even today, snow falls on both Mauna Kea and Mauna Loa. Both volcanoes are so high that snow falls during winter months, perhaps accumulating to a few meters depth. The seasonal snow cover on the steep slopes of Mauna Kea is easier to see from coastal areas than on the gentle, rounded slopes of Mauna Loa, whose summit cannot be seen from sea level.

The deposits are found between about the 11,000 and 12,000 ft elevation. The cinder cones left of the glacial deposits were erupted between 70,000 and 13,000 years ago, and the irregular surface below the cones and glacial deposits consist of lava flows erupted during the same time frame. (Public domain.)