Wetumpka is the sound the rock made when it hit.
Screwed that up.
http://www.auburn.edu/~kingdat/wetumpkawebpage3.htm#one
From Dr. King’s web page:
The town in Elmore County, Alabama, giving its name to the Wetumpka impact crater took its unusual-sounding name from a term in the Creek native people’s language: Awe-tum-cau@ which is derived from the union of Awe-wau@ (water) and Atumcau@ (rumbling; Read, 1984). Thus in Creek language, Wetumpka means Arumbling water,@ or alternatively Asounding or tumbling water.
These names are not entirely inappropriate for an impact crater that probably formed in shallow Gulf waters during the Late Cretaceous.