Wednesday, October 8, 2008

Different Types of Arches


According to Wikapedia "The choice of "bridge" vs "arch" is somewhat arbitrary. The Natural Arch and Bridge Society identifies a bridge as a subtype of arch that is primarily water-formed. By contrast, the Dictionary of Geological Terms defines a natural bridge as a "natural arch that spans a valley of erosion." http://en.wikipedia.org/wiki/Natural_arch#Weather-eroded_arches
While a bridge is one form of an arch, there are actually places in the world where the arch is so big that it is an actually highway on top making it a literal bridge. Carter Caves State Park is a cave eroded arch (made of limestone that has a paved road on top of it.
There are also Coastal Arches that form in two ways, Discordant Coastlines Which form at a 90 degree angle to the water, and Concordant which form parallel to the coast line.
The ones we are all most familiar with are the Natural Arches that from in Arches National Park. There is a cool Description of how they form in this blog, but also at this link. http://en.wikipedia.org/wiki/Image:Arch_form.gif

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