Step Canyon

Step Canyon (known to young Earth creationists as the "Little Grand Canyon") is a canyon on the foothills of Mt St Helens in Washington State, formed by a mudslide in 1982 after an earthquake.

Creationist abuse
Step canyon was formed "catastrophically" in a matter of minutes. It is thus used by creationists as an analogous - albeit significantly smaller - canyon to the Grand Canyon, so they can argue that the G.C. could have been formed in a similar way.

The facts
[T]here are no comparisons to Step Canyon (What YECers like to call the “Little Grand Canyon”) and the (real) Grand Canyon. Step Canyon goes through fields of unconsolidated pyroclastic flow deposits that is subject to easy erosion from the wet Pacific Northwest climate and there is a 2000 foot elevation drop within 1 mile, further adding to the erosion.

To put this in layman's terms, the Step Canyon was formed from weakened rock that was much more vulnerable to erosion, as well as having a very nearby drain-off point. The Grand Canyon on the other hand, is formed of an entirely different rock and has a runoff point much, much further away. Because of the massive differences between them, comparing the two is exceedingly stupid.