Haleakala Crater is now a cool, cone-studded reminder of a once-active volcano. Streaks of red, yellow, gray, and black trace the courses of recent and ancient lava, ash, and cinder flows. The volcanic rocks slowly break down as natural forces reduce them to minute particles which are swept away by wind, heavy rain, and intermittent streams.
A fiery birth beneath the sea
Modern geology indicates that the Hawaiian Islands are situated near the middle of the Pacific Plate, one of a dozen thin, rigid structures covering our planet like the cracked shell of an egg. Though adjoining each other, these plates are in constant slow motion, the Pacific Plate moving northwestward several centimeters per year. Scattered around the world are many weak areas in the earth's crust where magma slowly wells upward to the surface as a "plume". Here volcanoes and volcanic islands, such as Maui, are born.
This constant northwestward movement of the Pacific Plate over a local volcanic "hot spot", or plume, has produced a series of islands one after another in assembly line fashion. The result is a chain of volcanic islands stretching from the island of Hawaii along a southeast/northwest line for 4,050 kilometers (2,500 miles) toward Japan.
Mountains Above the Sea
Maui, one of the younger islands in this chain, began as two separate volcanoes on the ocean floor; time and again, eon after eon, they erupted and thin new sheets of lava spread upon the old, building and building until the volcano heads emerged from the sea. Lava, wind-blown ash, and alluvium eventually joined the two by an isthmus or valley, forming Maui, "The Valley Isle". Finally, Haleakala, the larger eastern volcano, reached its greatest height, 3,600 meters (12,000 feet) above the ocean - some 9,100 meters (30,000 feet) from its base on the ocean floor.
Waters Upon the Mountain
For a time, volcanic activity ceased, and erosion dominated. The great mountain was high enough to trap the moisture-laden northeast tradewinds. Rain fell and streams began to cut channels down its slopes. Two such streams eroding their way headward created large amphitheater-like depressions near the summit.
Ultimately these two valleys met, creating a long erosional "crater". At the same time a series of ice age submergences and emergences of the shoreline occurred; the final submergence formed the four islands of Lanai, Molokai, Kahoolawe, and Maui.
Lava Down the Valleys
When volcanic activity resumed near the summit, lava poured down the stream valleys, nearly filling them. More recently, cinders, ash, volcanic bombs, and spatter were blown from the numerous young vents in the "crater" forming multi-colored symmetrical cones as high as 180 meters (600 feet).
Thus this water-carved basin became partially filled with lava and cinder cones, and it came to resemble a true volcanic crater.
Stillness Within the Volcano
Several hundred years have passed since the last volcanic activity occurred within the crater. This stillness in Maui is attributed by modern geology to the constant northwestward movement of the pacific Plate. As the oldest islands on the northwest end of the chain have moved farther away from the plume - the source of new lava -they have ceased to grow; the ravages of wind and rain and time have thus been able to reduce them to sandbars and atolls.
Maui has shifted a few kilometers from the plume's influence, and Haleakala, too, is destined to become extinct. Though dormant now, about 1790, which is quite recent in geologic time, two minor flows at lower elevations along the southwest rift zone of Haleakala reached the sea and altered the southwest coastline of Maui. Today, earthquake records indicate the internal adjustments are still taking place in the earth's crust, but at present, no volcanic activity of any form is visible in the crater nor at any other place on the island of Maui. Perhaps Haleakala could erupt again; we just don't know.
Though Maui is no longer growing, the youngest island in the chain, Hawaii, is enlarging. And as plate drift continues, it is even probable that in the distant future, a new volcanic island will appear to the southeast of Hawaii, the Big Island.
The General park map handed out at the visitor center is available on the park's map webpage.For information about topographic maps, geologic maps, and geologic data sets, please see the geologic maps page.
A geology photo album has not been prepared for this park.For information on other photo collections featuring National Park geology, please see the Image Sources page.
Currently, we do not have a listing for a park-specific geoscience book. The park's geology may be described in regional or state geology texts.
Parks and Plates: The Geology of Our National Parks, Monuments & Seashores.
Lillie, Robert J., 2005.
W.W. Norton and Company.
9" x 10.75", paperback, 550 pages, full color throughout
The spectacular geology in our national parks provides the answers to many questions about the Earth. The answers can be appreciated through plate tectonics, an exciting way to understand the ongoing natural processes that sculpt our landscape. Parks and Plates is a visual and scientific voyage of discovery!
Ordering from your National Park Cooperative Associations' bookstores helps to support programs in the parks. Please visit the bookstore locator for park books and much more.
Park Specific Text Here
Information about the park's research program is available on the park's research webpage.
For information about permits that are required for conducting geologic research activities in National Parks, see the Permits Information page.
The NPS maintains a searchable data base of research needs that have been identified by parks.
A bibliography of geologic references is being prepared for each park through the Geologic Resources Evaluation Program (GRE). Please see the GRE website for more information and contacts.
NPS Geology and Soils PartnersAssociation of American State Geologists
Geological Society of America
Natural Resource Conservation Service - Soils
U.S. Geological Survey
Currently, we do not have a listing for any park-specific geology education programs or activities.
General information about the park's education and intrepretive programs is available on the park's education webpage.For resources and information on teaching geology using National Park examples, see the Students & Teachers pages.