He wa‘a he moku, he moku he wa‘a
The canoe is an island, the island is a canoe.¹

As they came around the Moon toward the Earth, they were greeted with an even more amazing view! They saw the Earth rising like a blue jewel over the bleak colorless horizon of the Moon. Astronaut Bill Anders said, “We came all this way to explore the Moon, and the most important thing is that we discovered the Earth.”² 

Live television images from the Moon were shared with a worldwide audience. The people of Earth saw an image of our tiny planet floating in a sea of black. Pictures showed the isolation and fragility of our planet. Viewers in their homes saw that we’re all unified together on our only home planet. People realized that we’re all in the same boat.

The Hawaiian Archipelago as a model of the planet as a whole

Knowledge can be our spacecraft, or wa‘a, to bring us to understanding and unity. It’s important to know something about the structure of the Earth and how life has adapted to thrive on it, in order to care for it. Understanding our role helps us find a connection to the earth. The only way we can live sustainably in harmony with the Earth is to experience a connection with it.

Hawaiians were expert ocean voyagers. They sailed thousands of miles across the vast Pacific Ocean on double hulled sea voyaging vessels called wa‘a. They knew how to live with limited resources, whether on a long ocean voyage or on an isolated island. They knew that human survival depends on being a part of the larger fabric of life on Earth. They settled on uninhabited islands by integrating themselves into the landscape and bringing abundance to the land.

Hawaiian mo‘olelo and akua, stories and gods, give insight into how we are connected to the earth. The legendary battle between Poli‘ahu and Pele on the slopes of Maunakea³ tells a story of how the erupting volcanoes interact with the high mountains of Hawai‘i. The mo‘olelo describes the different climate zones, geology and hydrology of the island. These stories inform us how the land functions. The akua connect people to the land through ancestry and inform us how to treat the land.

The Hawaiian Archipelago can be considered a model of the planet as a whole. Like the Earth in space, the Hawaiian Islands are tiny isolated specks of land in the vast Pacific Ocean. The Hawaiian Islands are isolated ecosystems that contain almost every kind of climate on earth. The Islands’ high mountains creates a diversity of climates usually found only on the continents. The climates range from cold alpine high in the mountains, to warm and wet at middle elevations, and hot and dry near sea level. The only climate zone missing in the Hawaiian Islands is the arctic zone with permanent frozen ice.

The structure of the Earth

The internal structure of the Earth is something like an avocado.⁴ The interior of the Earth is very hot. Most of it is soft viscous melted rock called magma. Heavier elements tend to sink toward the center of the Earth and lighter ones tend to accumulate toward the surface. At center of the Earth, about 7,900 miles (12,725 km) deep, is a solid core of heavy metals, like the seed of an avocado.

The inner core is the hottest part of the Earth, and it is kept in a solid state by the force of gravity. It’s about 9000°F (5000°C) at the very center. The temperature gradually decreases toward the surface. The force of gravity also weakens further away from the center of the Earth. The weaker gravity frees the outer layers of the core to release into a liquid state. The liquid outer core is a slightly less hot 7200°F (4000°C).

A magma filled layer called the mantle surrounds the core. The temperature of the mantle ranges from 7200°F (4000°C) near the core to 1300°F (700°C) near the surface. The composition of the magma varies depending on depth. Heavier elements near the core, and lighter elements toward the surface. The differences in temperature within the mantle create convection currents in the magma that causes it to churn and circulate. We have a basic idea of the structure of the interior of the Earth, but it’s still a bit of a mystery exactly what goes on down there.

The surface of the Earth, where we live, is covered by a thin crust of rock, like the skin of an avocado. It’s thin relative to the volume of the interior of the planet. The thickness of the crust ranges from 44 miles (70 km) under the continents to a thinner 3 miles (5 km)under the seabed. Thankfully, the crust is thick enough to insulate us from the molten rock below.

The crust is broken into enormous pieces that float on top of the molten mantle. These are called tectonic plates. These plates are slowly pushed around by the movement of the mantle below. The plates grow and shrink, they smash up against each other, they rotate, they go under and over each other. Volcanoes occur where there are cracks near the boundaries of the plates and holes through the plates. 

Hawaiian Lava

Most volcanoes are near the boundaries of the plates. Most of them are underwater. Above ground, Stratovolcanoes like Mt. St. Helens and Mt. Fuji are the more common stratovolcano type of volcanoes near plate boundaries.

Mount Saint Helens in the Pacific Northwest America is an andesite volcano. The source of its magma is from near the surface. When the molten magma of the interior comes out on the surface, it’s called lava. The lava of Mt. St. Helens is made of lighter elements. Andesite volcanoes tends to produce a lot of ash and can be explosive.

Volcanoes like Mount Fuji in Japan are fed by heavier magma from an intermediate depth of the mantle. This volcano is a mix of layers of lighter ash and lava that becomes hard basalt rock. Volcanoes like this tend to be cone shaped with steep unstable sides that are prone to erosion and landslides.

The Hawaiian deep magma source is different from magma from higher in the mantle that feeds other volcanoes. Hawaiian volcanoes are fed by a hole through the Pacific plate. Magma from deep in the Earth near the core flows up through the mantle in a plume that burns through the crust under Hawai‘i. This plume of extra hot magma is called a called a volcanic hotspot.

Both Mauna Loa and Kīlauea are active volcanoes on the island of  Hawai‘i. Hawaiian lava comes out of the ground as super hot fast flowing lava. The magma source near the core of the Earth produces lava rich in heavier metals like iron and low amounts of ash. It spreads out to form a broad flat volcano of hard basaltic rock, called a shield volcano. Shield volcanoes are very stable and can grow larger than other types of volcano. Maunakea, the largest volcanic mountain on Earth, is part of the island of Hawai‘i. Shield volcanoes form a wide foundation of strong stable rock. All of the Hawaiian Islands were formed by shield volcanoes.

The Hawaiian archipelago

The Hawaiian Archipelago is part of a  3,900 mile (6,200 km) long chain of islands. It spans from Hawai‘i island northward to the coast near Russia. All of the islands in the chain were once volcanoes that formed over the same volcanic hotspot where Hawai‘i island is today.

As volcanic islands form over the Hawaiian hotspot on the Pacific plate, the Pacific plate shifts the islands to the northwest. The surface of the Pacific plate moves about 3 to 4 inches (7–11 cm) a year. The volcanic islands very gradually drift off the hot spot, and stop erupting. A new volcano on the ocean floor starts to form an island over the hotspot where the old islands used to be.

The islands get progressively older toward the northwest. Islands shrink as they age by sinking down on the ocean floor under their own weight and eroding away on top. Some older volcanoes have eroded so much that they no longer appear on the surface. These underwater mountains, called seamounts, are the oldest part of the Hawaiian-Emperor seamount chain. The oldest seamounts that we can find near Russia are estimated to have formed around 80 million years ago. There may have been even more ancient islands that have totally disappeared. 

The Hawaiian Islands each provide a wide variety of soil types. The soil of Kaua‘i is about ten times older than Hawai‘i island. The same kind of lava formed both Hawai‘i and Kaua‘i. Erosion and oxidation over 5 million years has changed the soil on Kaua‘i to contain more fine clay that is redder with more oxidized iron. The islands get rustier as they age.

On the youngest island of Hawai‘i, fresh lava from deep in the Earth emerges from the Mauna Loa and Kīlauea volcanoes solidifying into solid rock. The northwest side which formed about half a million years earlier has become black mineral rich well draining soil.

Lava and the Ocean

The process of volcanic islands continually being formed to the east is described by one of the mo‘olelo of Pele.⁵ The legend describes the Hawaiian Archipelago as being a series of abandoned homes for Pele (lava). The oldest volcanic islands are to the west and become progressively younger toward the east. Each was formed by the same lava that erupts on Hawai‘i island today.

Mo‘olelo of Pele and Nāmakaokaha‘i

Pele is the goddess of lava. She originally inhabited a volcano in Kahiki⁶, but came to the Hawaiian Islands after a quarrel with her elder sister Nāmakaokaha‘i,⁷ the goddess of the sea and tsunami. The reason for the fight varies in different versions of the story. Some stories say that Pele seduced her sister’s husband. Others say that Pele destroyed part of her domain with fiery lava. In any case, Pele was forced to leave Kahiki and seek a new home.

Pele fled from Kahiki to Kaua‘i to escape the wrath of Nāmakaokaha‘i, but her sister saw the glow of Pele’s fire and followed her. Nāmakaokaha‘i, still in a rage, attacked Pele and sent a tsunami to flood the shores of Kaua‘i that extinguished the flames of Pele’s lava. Pele moved to O‘ahu and was again found by Nāmakaokaha‘i and assaulted once more. Pele retreated to Molokai, and then to Maui. Each time, Nāmakaokaha‘i relentlessly doused Pele’s fires with sea water.

Finally, Pele found a place high on the island of Hawai‘i where Nāmakaokaha‘i could not reach her. She dug a pit on the slopes of Kīlauea where the sea could not go. She still lives there today, in the caldera of Halema‘uma‘u.

Even though Pele is out of her reach, the fury of Nāmakaokaha‘i still rages. Whenever the volcano erupts and Pele flows down the slopes of Kīlauea, the sisters still battle where the lava meets the ocean.

This story shows that Hawaiians noticed that islands to the west were older. Even though volcanic craters can be found on all of the islands, Pele is only active on Hawai‘i island. The story also lists places that are susceptible to the waves and tsunami of Nāmakaokaha’i.

Knowing the shape of the Hawaiian Islands helps us understand how weather and water interact with the surface of the islands to create different climate zones. Knowing the geologic structure inside the Islands helps us understand how water flows and collects inside the islands.