Arches National Park Quarter
Nero here, and I'm pretty amazed about this month's coin. It's the Arches National Park quarter, new in 2014, and the star of this quarter is actually a rock.
Now, this isn't the first “rock star” that appeared on a coin. We've seen the “Old Man of the Mountain” on the New Hampshire quarter, “Half Dome” on California's quarter, Mount Rushmore on the South Dakota and Mount Rushmore National Memorial quarters, and “Little Stony Man” on the Shenandoah National Park quarter just recently, to drop a few names. (This star's name is Delicate Arch, by the way.)
Anyway, we think of rocks as hard, and they are. But what amazes me is how much they can change, even though the change is slow by mammal standards.
For one thing, the arches in Arches weren't always arches. They used to be a bed of sandy sandstone on a bed of clay sandstone. Erosion from wind and water (even in the desert), sand, and moving Earth-crust all shaped the arches and fins we see today, and are shaping them still.
Also, the holes under the arches grow until the arch falls apart. Although these arches don't fall often, it can happen any time. For instance, Wall Arch collapsed in 2008 without any warning. It wasn't cracked like Broken Arch or thin like Landscape Arch, but down it came.
Landscape Arch is another example. It's the longest arch in the Park (306 feet from base to base). In 1991, a huge slab of rock fell from its underside, making the arch even thinner, yet it remained intact. Even the thunderous rumble of Wall Arch as it fell didn't cause Landscape Arch to cave in. But some day, all these arches will be gone. So enjoy them while you can…all 2,000 plus!
Another way arches change is in their coloring. Most have horizontal lines of color. Those lines are layers (strata) of rock types. But rocks can also have vertical lines called “desert varnish.” Manganese and bacteria work together to cement clay and other particles to the rock's surface, forming streaks of black, brown, red, and orange.
Now that I know how much rocks change, I'm sure glad Delicate Arch held still long enough to get its picture taken for this quarter! Read more on the Arches National Park Quarter page!