Rock arches are one of my favorite wonders of the natural world. The idea that they were

organically formed seems almost impossible, but of course they are. The technical

definition of 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. There are about 2,000 significant natural arches in the U.S.

A significant natural arch has two orthogonal opening dimensions

with a product of 10 square meters or more.

Of course, there are many more smaller arches.

This stuff gets intense.

There's actually an entire society of arch levers called the Natural Arch and Bridge Society, whose

$16 membership fee gets you for issues annually of Spann magazine.

You can find more info than you ever thought you could find about rock arches on their website.

From the different classifications, measurements, techniques, how they're formed, how they get named, it's a fascinating rabbit hole to go down if you have some time to kill.

There's one arch that's known better than all others in the US. In fact, it's on the

state of Utah's license plate. It had its own postage stamp and the 2002 Winter Olympics torch relay passed through it.

On this episode of America's National Parks, Delicate Arch, and the strange history of attempts to protect it at

Arches National Park.

Here's Abigail Trepute. Arches National Park is home to over 2,000 natural arches that have been carved from tall, fin-like sandstone formations over the course of a millennia.

Sandstone is made of grains of sand cemented together by minerals, but not all sandstone is the same.

In Trota Sandstone was once a massive desert of fine-grained shifting dunes. The nearly spherical grains, when compressed together, formed a rock that is

highly porous. The caramel layer, just beneath the entraut is composed of a mix of sand and clay.

Clay particles fill in gaps between the sand grains making the rock denser and less permeable.

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