What is a natural arch?
A natural arch is a rock exposure that has a hole completely through it formed by the natural, selective removal of rock, leaving a relatively intact frame.
A natural arch must be made of rock.
The rock must be exposed.
The hole through the rock must conform to the mathematical, or topological, definition of a hole.
The hole must have formed from natural, selective removal of rock.
The frame of rock that remains to surround the hole must still be relatively intact.
To qualify as a natural arch or bridge, the passageway should be at least 15" at the widest point, and at least 15" at the highest point. Smaller openings are called windows, lighthouses, or holes. An arch or bridge is created by differential weathering of the softer rock stratum leaving the harder rock stratum intact. The most common differential weathering is moisture freezing and expanding causing the rock to crack and fall away. Others include wind, windborne debris, rain, and wave action. A natural bridge is caused by wave action where the water is eroding, running underneath, and creating the formation.
Please email me the answers to the following questions :
1. Estimate the width and length of the passageway.
2. What natural process do you think formed the arch?
3. What type of stone is the arch?
You are welcome to post photos of your visit to the site, but this is optional and not part of the logging requirements.
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(Permission for this EarthCache given by geocaching volunteer contact for BIP.)