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| Very diverse landscapes, including tall cliffs, lush forested valleys and plummeting waterfalls, which all have been created as a result of several types of weathering and erosion. |
North Kauai reveals many dramatic aspects of weathering, surface hydrology, and erosion. The Nā Pali Coast's 17-mile coastline took millions of years to form. One aspect about the Nā Pali Coast, which I find interesting is that due to it's geographical location, rugged landforms and climate, it is considered one of the least accessible coasts in the world.
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Kauai's climate and annual precipitation will be discussed in my next post, but I think it is important to mention that rainfall has a profound effect on weathering. This area receives an average of 100 inches of rain per year, which affects the hydraulic properties of sedimentary rocks, especially within ash.
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The Nā Pali Coast has been featured in many movies including, Jurassic Park and King Kong.
"Na Pali" means "The Cliffs" in Hawaiia
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As we
know now, Kauai’s origin is volcanic. The
Nā Pali Coast’s cliffs are composed of basaltic lava flows. The steep 4,000 foot cliffs that make up this coast were formed as the
result of a huge landslide millions of years ago. The landslide was created by a change, or shift and forced part of the land to slip down into the ocean.
Chemical weathering, salt
weathering, and erosion have continued to sculpt and form this area making the
Nā Pali Coast the second fastest eroding location in the world.
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| (Strong wave action along the coast) Note the crossbedding layers of Basalt and how its color and stratigraphy have changed due to oxidation |
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| ( Vertical slopes, with knife-edged divides and steep chutes formed by landslides, water runoff and other forms of weathering ) |
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| (Perfect example of oceanic waves breaking down a weak zone in a rock and forming a sea cave) |
The sea caves along the Nā Pali Coast are an unforgettable sight. Sea caves originate in the side of a costal cliff along a weak zone, known as a fault or crack. The Nā Pali Coast’s sea caves are formed by a dike, which is when a well-eroded rock is found within a stonger, larger rock. Due to wave action, the weak area in the rock begins to erode and caves are able to form.
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| (View of a sea cave along the Nā Pali Coast by boat) Notice the cracks and fischers as well as the calcite, deposited by water percolating through the permeable bassalt rock |
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| (An areal view of a sea cave along the Nā Pali Coast) Notice the salt crystal growth in the ridges of the rocks as well as the areas where the soil was been oxidized |
The Nā Pali Coast's weathering and erosion is not all caused by organic and environmental changes. It was discovered recently that hikers and campers, as well as feral animals, such as pigs and goats created unnatural erosion process and were damaging the natural ecosystem of this unique area. This was creating more rockfalls, mudslides and reef siltation. Currently, efforts are being made to slow down this unnatural process.
External links:
Coastal Geology
