GC5G966 Kalalau Valley - Pu’u O Kila Lookout (Earthcache) in Hawaii, United States created by Forest-Ghost

GC5G966 ▼

A cache by Forest-Ghost Message this owner

Hidden : 12/7/2015

Difficulty:

Terrain:

Size: Size: other (other)

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Geocache Description:

At the very end of Highway 550, in Kokee State Park, awaits one of the most jaw dropping views on the island. From here you can see a spectacular panorama of Kalalau Valley and the Alakai Swamp, the highest swamp in the world and the wettest place on earth. From this point the ocean is just 2.5 miles away and over 4000 feet below you. You can venture right up to the edge of the valley to snap that perfect photograph.

Arriving to a clear view at Pu’u O Kila Lookout can be hit or miss as the valley is sometimes filled with clouds that obscure the view. The best time to visit is before 11 AM, as the clouds are constantly moving in and out of the valley and are especially thick in the afternoons and evenings. Several people have also noted that if you wait 15-30 minutes, the view may clear up. Wind blowing in or out from the main land can also factor into the amount of cloud coverage in this area.

Using observations from the area and information from the cache page, email me answers to the following questions:

Near the posted coordinates you will see a sign with the words “WAI’ALE’ALE” written at the top. Based upon the sign, how would you describe the environment here? What is the elevation?
Observe the rocks and soil at this location. What color(s) do you see? How has erosion affected the color of the earth?
What factors have caused erosion/shaping of this valley?
Assuming the base of the valley floor is at 0 feet elevation and the vertical erosion rate is approximately 0.03 cm per year. Approximately how long did it take (in years) for this valley to deepen?

Volcanic Formations

This area has a unique geologic history—it was formed not only by the steady process of erosion, but also by the volcanic erupions that occured in this area millions of years ago. Like the other Hawai‘ian islands, Kaua‘i is on top of an enormous volcano rising from the ocean floor. With lava flows dating to about 5 million years ago, Kaua‘i is the oldest of the large Hawai‘ian islands. Roughly 4 million years ago, while Kaua‘i was still erupting, a portion of the island collapsed. This collapse formed a depression, which then filled with lava. This area we now call Waimea Canyon. Going to the other side of the ridge we see the sheer cliffs and drop offs of the Nä pali coast. Nä pali, which is translated “High Cliffs,” were partly formed through the lava that flowed through here millions of years ago.

Thousands of Years of Erosional Forces at Work

The deep gullies and canyons cut into the highlands of the Nä pali coast were also formed from the erosive forces that have been at work in this area. In the north and northwest of Kauai the roaring waves of the Pacific Ocean hit the island after travelling for thousands of miles undisturbed. These waves meet a steep and rugged coastline with swells that can reach 10 m high on the Na Pali Coast.

Rainwater from the slopes of Mount Wai‘ale‘ale (one of the wettest spots on Earth, with 450 inches of rain a year) have also eroded the deep valleys we see today. Fresh water cascades in many places hundreds of meters as waterfalls and other runoffs that shape Na Pali's unique fluted cliffs and meandering coastline.

The water runoff has also helped to create a lush seascape of vibrant green mountains. The extreme steep sided valley walls of the Nä pali coast are covered with extensive vegetation supported by surface water draining seaward off of Mt. Wai‘ale‘ale. These plants, with their roots and botanical acids, have weathered the chemically unstable lava rocks here as well.

Oxygen in the atmosphere has also caused erosion in this area. As the older lava weathers, the minerals in the rocks oxidize and often turn to clay minerals. The once shiny basalt, (a type of rock formed from lava) becomes dull and cloudy, or the glassy surface breaks and falls away to expose the dull interior. One of the most common minerals found in the decomposed rock is hematite, an iron oxide that is usually yellow-brown or rust colored. The red colors we see along the Napali coast and in other parts of Waimea are a result of this oxidation.

This cache was placed with permission from the Na Pali Coast State Park.