The Hualalai Volcano is one of five volcanos on the Big Island of Hawai'i -- Kohala, Mauna Kea, Hualalai, Mauna Loa, and Kilauea. Kilauea Volcano is the world's most active volcano, with the most recent eruption beginning in 1983 and continuing through today. Mauna Loa Volcano last erupted in 2022. Hualalai's eruption was in 1800-1801, but is expected to erupt again in the future, and is continuously monitored by the Hawaiian Volcano Observatory nearby. No significant evidence of any impending eruption has been seen for decades.
The last eruption of Hualalai occurred in 1800-1801 that created two lava flows both of which flowed to the ocean. The Ka'upulehu Flow was the northern-most lava flow. (The southern flow -- Hu'ehu'e -- created Keahole Point, where the Kona International Airport is located.)
The Ka'upulehu Flow is unusual in that it contains xenoliths, a non-igneous rock contained within the lava. Many times this foreign rock is brought to the surface with the lava as it flows from its source, and may be part of the earth's mantle.
At the coordinates you will see a smallish lava flow, composed of both a'a and pahoehoe lava. The volcanic igneous rocks of this lava flow vary in color from grey to dark red to black. You will need to walk around and look closely at the rocks until you find a xenolith. It will be imbedded in the volcanic rock and will look remarkably different. (Some of the north-facing rocks have lichen growing on them. This is not a xenolith.) There are a large number of xenoliths in this area, and you should find at least one with a little effort. Please be careful since you will be walking on lava rocks which can be rather sharp and unstable at times.
Then, proceed to the waypoint. Face the ocean, observe the lava flow field, and determine the size of the flow field. Also, determine the type of lava that comprises the field, either 'a'a or pahoehoe. 'A'a lava is rocky, with many sharp edges. Pahoehoe lava is ribbony, like thick cake frosting
To log this geocache, please send me, by email, answers to the following questions:
1. Describe the xenolith that you have found. What does it look like? How is it different from the lava rock that surrounds it? What are the xenolith dimensions?
2. At the waypoint, what type of lava comprises the flow field, 'a'a or pahoehoe?.
3. At the waypoint, what is the size of the lava flow field, in yards or meters?
References: 1. http://www.sandatlas.org/xenoliths-in-hawaiian-lava/; 2. Roadside Geology of Hawai'i, Richard W. Hazlett, et al., 1996; 3. Volcanoes in the Sea, Gordon A Macdonald, et al., 1983.