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.
|—Lance Wilson, on a Panda's Thumb comments page.|
As you can see, there really is no way that creationists can honestly compare the two features. Step canyon 'carves' its way through "unconsolidated pyroclastic flow deposits", the Grand Canyon through "lithified limestone, sandstone, and shale." Just because the former can happen in a catastrophic manner doesn't mean that the latter did, or even could.