On the drive to the summit of Mauna Kea, we pass Hale Pohaku, which is where all the astronomers stay before they go observing at the summit so that they can get accustomed to the altitude. This is also a fine place to look south towards Mauna Loa ( Stop #10 ) to observe the gentle slopes of this shield volcano. In the foreground are some of the cinder cones that formed on Mauna Kea relatively recently as the volcano moved away from the Hawaiian hotspot.
Closer to the summit, we discover an unusual feature for Hawaii -- glacial deposits! Mauna Kea is so high that during the last ice age there was a small glacier at the summit (snow still falls on the summit each winter). This glacier created a series of moraines made of fragmented volcanic rock that were transported downslope, only to be deposited as the moraine seen here. Because Mauna Kea has not erupted for about 3,000 years, many glacial features are preserved on this volcano, whereas similar features that no doubt formed on the adjacent Mauna Loa volcano have been buried by younger lava flows.
The summit of Mauna Kea is a very wild place, more like the surface of Mars than the tropical island that we see at lower elevations. All of the small hills in this image are cinder cones that have formed by small explosive eruptions of the volcano. The boulders in the foreground are either ejecta from these eruptions or they are blocks transported here by glacial activity a few thousand years ago.
The summit of Mauna Kea is the home of ten giant astronomical telescopes, and there are plans for 3 more to be constructed here. The high elevation, dark skies, and stable atmosphere in the middle of the Pacific Ocean make Mauna Kea the world's best site for optical telescopes such as the ones seen here.
The summit of Mauna Kea is truly an international resource. There are telescopes operated not only by the United States but also by Canada, France, Japan and Great Britain. Students at the University of Hawaii also benefit from the outstanding facilities here, since 10% of all observing time is reserved for Hawaii's astronomers.
From here you can continue on to Stop 9 on the ground, or you can pick another point from the Big Island Virtual Field Trip page.