Kahoʻolawe – Single Shield Volcano EarthCache

If you look out about seven miles south west you will see the island of Kahoʻolawe. (You are looking at the large island, not the small cindercone volcano crater of Molokini.) Kahoʻolawe is the is the smallest of the eight main volcanic islands in the Hawaiian Islands, standing about 11 miles long by 6 miles wide, with a total land area of 44.97 square miles.

The main Hawaiian Islands are the tops of giant undersea shield volcanoes. Kahoʻolawe, is a single shield volcano, that consists of a nearly filled caldera and a rift zone that trends to the southwest.

A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. It is distinct from the other three major volcanic types: stratovolcanoes, lava domes, and cinder cones, by their structural form. Shield volcanos are named for their large size and low profile, resembling a warrior's shield lying on the ground.

When a Shield volcano erupts the very fluid lava travels farther than lava that comes from stratovolcanoes. This results in the steady accumulation of very broad sheets of lava. These sheets build up on each other and create the volcano’s distinctive shield shape. Shield volcanoes contain low viscosity magma, which gives them a flowing lava that is made of a silicate mineral rich in magnesium and iron, giving the island its dark appearance.

A very distinctive feature of shield volcanoes are the rift zones; rift zones are very rare in other volcano types. The rift zone is a linear series of fissures that allows lava to be erupted from the volcano's flank instead of from its summit. In a Rift zone the rock has many long cracks and is relatively weak, so it is easier for the magma to make its way to the surface through the rifts, rather than through the summit. It is the lava flowing from the long rift zones that cause the volcano to have an elongated shape, rather than a tall cone shape.


Logging Requirements and Questions:
Please send an email with the following information....
1. The Text " Kahoʻolawe – Single Shield Volcano” on the first line.
2. The Number of People in your group.
3. Although shield volcanoes are relatively flat, they do have eruption points, which form peaks. From this vantage point, how many peaks are visible?
4. Can you see any rifts from this location? If so describe them, if not why do you think they are absent?
5. What is a distinctive feature of the shield volcano?
6. How did the Shield volcano get its name?

OPTIONAL: A picture of you, your group or your GPSr with the island of Kahoʻolaw in the background.

Parking at: 20° 37.904'N 156° 26.675'W
From the parking coordinates take the dirt path to the beach, about 350 feet.