The massive Haleakala shield volcano forms the eastern portion of the island of Maui and covers approx. 75% of the islands’ area. The summit is at 10,023 feet (3055 meters). Haleakala (“house of sun”) contains a 2.2 x 5.9 mile (3.5 x 9.5 km) summit crater that is widely breached on the north and southeast sides. The “crater” is not of volcanic origin, but formed as a result of the coalescence of head ward erosion of two valleys. Subsequently the crater has been partially filled by a chain of young cinder cones and lava flows erupted along a major rift zone that extends across the basaltic shield volcano from the southwest to the east flanks. Another less prominent rift zone extends north from the summit. The most recent eruption of Haleakala could have occurred between 1450 and 1650 (due to radiocarbon measurements).
Like all on the Hawaiian islands, Haleakala is a shield volcano. Lava flows upwards from a hot spot in the earth’s mantle as a tectonic plate moves it. Melting of the upper mantle causes magma to rise up through the ocean floor, slowly accruing over time until at last a volcanic island emerges from the sea.
As with icebergs, these volcanoes show only a small part of their total mass above water, leaving 95% below on an ocean seamount. In its prime, Haleakala was much higher, before water and wind erosion began to carve two large river valleys out of the rim. Eventually, these valleys formed gaps that merged at the volcano summit to create a crater-like basin.
To log the cache please go to the lookout and answer the following questions:
1. How high was Haleakala at the end of the first great period?
2. How high was Haleakala at the end of the second period of growth?
3. Tell me the complete English explanation of “Pu’u Kumu”.
4. Through which gaps is the material washed away?
Due to your own observation: which gap is larger?
5. What accelerates the erosion?
6. How many cinder cones can you see from the lookout (may vary depending on the weather)?
7. (optional) take a picture of you at the lookout – without spoilers please
Send the answers to kala.haku@web.de. You must not wait for the reply. I will send you a confirmation and tell you if I have any questions.
The answers must be send within 24 hours after logging. Otherwise the logs will be cancelled.