The Story of Waihe’e: The source of the land
Walking along the coast of the Waihee Refuge today, listening to the sounds of the wind that the kupuna called Ka makani kili oopu, a 1.6 million year old story unfolds beneath your feet. In some ways this story is the story of the entire Hawaiian archipelago, but there are some twists to this story that combine to make Waihee unique. While humans have only walked this land for just over a thousand years, the geological forces that shaped Waihee are written in broad strokes across the entire landscape.
The mountain that rises up from the refuge, variously known as Mauna Kahalawai, Puu Kukui, and sometimes simply the West Maui Mountains, is a geologically young 1.6 million years old. Haleakala, visible across Kahului Bay, by comparison is a geological infant at a mere 1.2 million years old. It is important to note, however, that the ages used to date these volcanoes, which geologists simply call shield volcanoes, are dated to the time when they reached their peak in height. In reality, Mauna Kahalawai and Haleakala stopped growing 1.6 million years and 1.2 million years ago respectively. Both mountains were undoubtedly substantially higher at their peak, but millennia of erosion has reduced their height, and on Mauna Kahalawai in particular, there are deeply incised large valleys where streams flow to the ocean today. At the edge of the Refuge, the Waihee Stream flows into the ocean at a rate of about 15 million gallons each day.
What gives the Waihee Refuge one of its most unique characteristics are the sand dunes that surround it, creating a hollow of sorts, a feature that contributed to the Hawaiian name for this area, Kapoho, or the hollow. If Mauna Kahalawai is defined today by the erosion that shaped its many valleys, Kapoho is defined by these sand dunes. These dunes, which geologists refer to as Aeolian, or wind-blown dunes, are the result of the power of the ice ages. Typically, most of us do not think of ice ages as shaping these islands which lie in the northern tropics. However, Waihee is a testament to the power of these frigid epochs to shape and transform landscapes even thousands of miles distant from the glaciers that shaped North America.
Two ice ages are notable in the geological formation of Maui, Mauna Kahalawai, and Waihee. The first occurred when Haleakala had recently completed its shield building phase and probably rose to an elevation between 12 and 14 thousand feet occurred approximately 1.2 million years ago. This glacial period occurred during the middle of the last geological time period, the Pleistocene, and was particularly severe. With vast volumes of water captured in the northern hemispheres ice caps, sea levels around all of Hawaii dropped hundreds of feet; so much in fact, that the islands of Maui, Molokai, Lana’i and Kahoolawe became one massive island. So large, that this massive island, known colloquially as Maui Nui (or great Maui), was approximately 20% larger than Hawaii Island is today. The massive size of Maui Nui accounts for Maui’s incredible biodiversity, as large islands, unsurprisingly, capture the largest number of species flying (or floating) over the vast Pacific Ocean. Little remains to be seen of this powerful ice age in Waihee today, but the signature of the next glacial period, quite literally surrounds the Waihee Refuge.
After a long period of a relatively warm global climate, approximately 21,000 years ago the earth, and the northern hemisphere in particular, went through another intense period of glaciation. Known as the late Pleistocene ice age, and more specifically, the Wisconsin period of glaciation. Sea levels around Hawaii dropped approximately 300-400 feet. Kahoolawe remained independent of Maui Nui island during this period, suggesting a less intense ice age than the previous glacial period. However, because the fringing reef system in front of the Waihee Refuge had built up for well over a million years, its exposure and disintegration over the next 10,000 or so years created the sand that built up and formed the dunes that would, many millennia later, come to be called Mauna Ihi.
Remnants of these dunes once extended from Kalaekahoomano, the point directly above the Waihee stream, through Wailuku around Kahului nearly to Waikapu. The dunes that once covered much of Maui’s central valley remained a prominent feature of the landscape, a testament of the power of ice ages to impact landscapes thousands of miles to the south. While anthropogenic modifications have dramatically changed the landscape, in her travel journal English explorer and travel writer Isabella Bird described her travels between Wailuku and Haiku in 1873 as a trip through a “mini Sahara Desert.” Today, the 200 foot dunes of the Waihee Refuge are the last unmodified reminder of earths last glacial maximum.
Another striking reminder of the power of natural phenomenon to shape and carve the landscape comes when standing at Kalaekahoomano above Waihee stream, looking north west along the Kahakuloa coast. The cliffs along this rugged coast are a reminder of the fragility of Hawaiian shield volcanoes. For many decades, geologists have known that Hawaiian shield volcanoes are prone to what is sometimes described as ‘flank failure.’ Simply put, massive chunks of the volcanoes that make up Hawaiian volcanoes will shear off into the ocean. The 300-400 foot cliffs along the Kahakuloa coast seem to be evidence of flank failure. With the collapse of a portion of the mountain, the tsunami this event generated would have been catastrophic for any living (flightless) creature in Waihee. Although no estimate of the volume of this catastrophic event has been calculated, by comparison, the massive flank failure on the island of Molokai approximately 1.5 million years ago, generated a wave estimated at a height of over 1,900 feet. While the Kahakuloa flank collapse would have been substantially smaller than that, the numerous water worn rocks that line the coast of approximately half of the Waihee Refuge are a reminder of the intensity of these catastrophic events.
Finally, as Mauna Kahalawai aged and eroded, the power of water became more prominent across the landscape. While most of that water seeped into the basin that makes up the Waihee stream, a smaller, but substantial portion of that water flows underground, and emerges in springs along the coast. While one large spring was located at the base of the sand dunes, numerous smaller springs are located within Kapoho, surrounded by the dunes, and these springs collectively make up the 27 acres of wetlands in the heart of the Waihee Refuge.
Volcanoes, sea levels ebbing and flowing, flank collapses and the slow power of water each in their own way have come to create and shape this land that we have loved and cared for over the past decade and a half — an insignificant point in the great tapestry of time. Understanding these geological processes is a reminder of our connection to the land, and how truly small we are within the vast scope of the history of the land. He alii ka aina, he kauwa ke kanaka (the land is the chief, and people are its servants), never rings more true than when we understand our place on the landscape.
— Dr. Scot Fisher