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LOCATION: Hawaiian Islands, East Pacific Ocean

GEOLOGIC FEATURES: Basaltic Lava Flows; Shield Volcanoes; Hot Spot; Weathering and Erosion


DESCRIPTION: Waimea Canyon on the Hawaiian Island of Kauai offers an opportunity to observe the internal structure of this 4 to 5 million year old (Pliocene) Shield Volcano. The Canyon, found along the west flank of MtWaialeale volcano, stretches over 10 miles in length with a depth of about 3500 ft.  It is known for its black, red-brown (oxidation of iron) and green colors and numerous waterfalls that cascade into the Waimea River. It is often referred to as The Grand Canyon of the Pacific. As opposed to the Grand Canyon in Arizona, however, the rock layers are lava flows composed of the igneous rock basalt and not layers of sedimentary rock. Basalt is a dark igneous rock that flows readily due to its relatively low silica content.


Kauai is the oldest main island of the Hawaiian Island Chain being located farthest away from the present-day Hot Spot to the southeast that created the island.  (The reader is referred to the Hawaiian Islands National Park Field Trip top found in this website for a more comprehensive study of the geologic origin of the Hawaiian Island Chain.) 


As the oldest island, it has been subjected to the effects of weathering and erosion for the longest period of time.  Rainwater from the slopes of Mt. Waialeale to the east (almost 450”/year – one of the wettest spots on Earth) has funneled water to the south-flowing Waimea River which eroded Waimea Canyon.  In addition, an underlying north-south trending fault zone, representing a former collapse of the volcano’s western margin, helped to provide softer, broken up material that helped shape the path and increase the erosive capability of the river in carving this deep Canyon.


(1) Why would one expect Kauai to be the most deeply weathered and eroded of the major Hawaiian Islands?

(2) Why is Kauai the smallest and oldest of the major Hawaiian Islands?

(3) Explain the variation of colors found within Waimea Canyon.

(4) Many flows, especially within the western side of Waimea Canyon, will dip slightly towards the west.  Explain a possible reason why.

(5) CHALLENGE: How are layers of lava found in Kauai’s Shield Volcano (and all the Hawaiian Islands) different from those associated with massively explosive volcanoes found elsewhere on Earth, such as at Yellowstone, Mt. Vesuvius, or Mt. St. Helens ?



-Hawaii State Parks. The History and Geology of Waimea Canyon State Park.  Accessed January 9, 2024 from

-Harris, D.V. and E.P. Kiver. 1985 (4th ed.). The Geologic Story of the National Parks and Monuments (4th ed.), John Wiley and Sons, New York, 464 pp.

-Macdonald, Gordon A, Dan A. Davis, Doak C. Cox. 1960. Geology and ground-water resources of the island of Kauai, Hawaii. USGS, U.S. Department of the Interior, Hawaii Division of Hydrography, Bulletin 13. Accessed January 9, 2024 from

-NASA Earth Observatory. Waimea Canyon, Kaua’i. Accessed January 9, 2024



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Figure 1 - Waimea Canyon. The 3.8 mile long Waimea Canyon Trail offers many scenic views. Here, from Pu'u Hinahina Lookout, the 800 ft cascading Waipoo Falls runs over the layers of basalt to eventually enter the Waimea River. (Photo by Eric Marintsch and Kelsey Hisako, Naturalists)

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Figure 2 - Waimea Canyon. Another view from Pu'u Hinahina Lookout.  (Photo by Eric Marintsch and Kelsey Hisako, Naturalists)

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Figure 3 - Waimea Canyon.  Viewed from Waimea Canyon Overlook, hues of black, red, brown. and green permeate the landscape. Iron within the black basaltic lava reacts with oxygen to produce red to brown iron oxide.  Green vegetation thrives in the rich soil produced by the weathering of the basaltic layers.   (Photo by Eric Marintsch and Kelsey Hisako, Naturalists)

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Figure 4 - Waimea Canyon. Having been exposed to weathering and erosion longer than any other major Hawaiian Island as well experiencing the most rainfall of nearly any other place on earth, the main Canyon and side canyons are carved deeply through 4-5 million year old layers of igneous Basalt. Photo by Eric Marintsch and Kelsey Hisako, Naturalists)

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