Alabama Hills - Arches and Tafoni
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Please be aware that this is an Earthcache, which requires you to answer the questions in the assignment mentioned in the cache description. Please send these answers via our profile on Geocaching.com. Feel free to contact us if you have questions regarding the assignment or any other comments to the cache.
Alabama Hills - Arches and Tafoni
When driving or walking through Alabama Hills you will notice two main types of rocks: Orange rocks which were formed 150-200 million years ago and granite rocks which are somewhat younger. They were exposed about 90 million years ago. In this Earthcache we will focus on the granite formations. Since their exposure, erosion has played a significant role in shaping the rocks. In this area you will find dozens (or even hundreds) of natural arches, formed by time and the elements.
In addition to the arches you will also notice some other interesting features, the so-called tafoni, which are concave hollows. There is still some debate about the explanation of their formation, and several different mechanisms are probably in play. Take a look at this web page, which is dedicated to tafoni.
Now, let’s focus on your assignment, which consists of two tasks:
Start your trip at the parking area and follow the Alabama Hills Arch Trail to the given coordinates. You will arrive at the famous Mobius Arch which is one of the most photographed features in Alabama Hills. Explore the area and remember to enjoy the view to Mount Whitney through the arch. Mount Whitney is the highest mountain in California (and for that matter in the lower 48 states). You will see the mountain when looking through the arch towards the West (approximately 255°). Taking a photo of Mount Whitney as seen through the arch at sunrise is every photographer’s dream. Part one of your assignment is to estimate the height of the Mobius Arch. Please give us your best estimate of the distance from the floor to the underside of the arch.
Your next task is to identify a tafoni and estimate the size of it. When standing under the arch facing (approximately) North-East you will notice two hollows in the rock opposite the arch. The hollow to the left is elongated (horizontally), whereas the one to the right has the shape of a half sphere. What would you estimate the diameter of this somewhat smaller tafoni to be?
To sum up: Please email us the answers to these two questions:
1. What is the height inside the Mobius Arch (the opening from the floor stone to the underside of the arch)?
2. In the rock just Northeast of the arch two tafoni may be identified. What is the diameter of the tafoni to the right (which is shaped like a half sphere)?
You are welcome to use either meters/centimeters or feet/inches, and you are welcome to answer in English, German or Danish.
We also very much appreciate you uploading a photo with your log (preferably of you or someone from your team with the beautiful rocks in the background), but please do not post anything which will give away the answers to the two questions.
Alabama Hills on Wikipedia
Arches of Alabama Hills
Mount Whitney on Wikipedia
Total number of visits:
(No hints available.)
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Coordinates are in the WGS84 datum