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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
Hello Jodie! Kaua'i looks fascinating! It's very interesting to learn how chemical weathering can cause such beautiful but also dangerous views. The pictures and figures you have included help me understand more of how the Na Pali Coast is forming. I had forgotten how strong waves can be and how they can form sea caves. This coast reminded me of a coast I had been in Greece that almost looked like a pool; when the water was calm anyone could swim in there, it was an exciting experience.
ReplyDeleteI had no idea that erosion could be such a big effect on landscapes like this one.
I learned a lot from your blog, I hope I can visit Kauai one day!
Thanks!
Alexandra Kapodistrias
Hi Jodie, it's nice to finally get the chance to see your blog. A few questions came to mind on your third paragraph. You describe how the "steep 4,000 foot cliffs" that comprise the majority of the coastline were all formed through "huge landslides". The way you described the landslide and the illustrative picture you provided seems to suggest that the process might have been rotational slump. Is there a reason why you chose not to describe it this way? Also, do you mean to say that the whole coast experienced a landslide in the same way and at the same time? It seems like that's what you mean, and if this is the case I think that this event you describe is very interesting. Maybe you could discuss in a little more detail how this happened (how the entire island of Kaua'i experienced a "landslide" or "slump" at the same time to create the Kaua'i coasts as we now know them) and maybe clarify how such an event could happen. If this actually didn't happen (i.e. the entire coastline of the island being created all at once in one event) and you meant something else, a little extra explanation could help clarify what you mean exactly.
ReplyDeleteSometimes you list a form or process but afterwards you don't explain what they are (e.g. in the third paragraph you mention "basaltic lava flows", "chemical weathering", and "salt weathering"). It might be useful to explain the process or form briefly; in explaining them, you would also be fleshing out the implied things that I sense are there. For instance, after you mention "chemical weathering" and "salt weathering" in the third paragraph you mention how the Na Pali Coast is the fastest eroding location in the world. I'm fascinated by this comment but I'm not clear how that would be the case. If you described the processes you listed (especially from the perspective of this comment) you could explain how the coastline owns the status of the fastest eroding location in the world without having to even go out of your way to do so. So I would suggest that it might help make your good blog a little better by explaining the listed processes in a little more detail. Anyway, I think your blog is pretty, well designed and interesting to read. Good luck the rest of the semester.
Anthony Cordova