Your rewrite rule says "redirect /anything to /mediawiki" -- that includes /mediawiki, hence the loop. Unless you add the [L] (last rule) flag, the targets of rewrite rules are themselves evaluated.

In an environment where plants and animals must adapt and invent to survive, desert washes play a critical role in managing life's most precious commodity. These serpentine natural gutters corral and ...

Firefighters believe an electrical problem sparked the fire on Apache Loop, but fire investigators said arson is suspected in the other two. Jan. 2, 2004 Firefighters believe an electrical problem ...