The Collaborative International Dictionary of English v.0.48:

Huronian \Hu*ro"ni*an\, a. [Named from Lake Huron.] (Geol.)
   Of or pertaining to certain non-fossiliferous rocks on the
   borders of Lake Huron, which are supposed to correspond in
   time to the latter part of the Arch[ae]an age.
   [1913 Webster]