The Collaborative International Dictionary of English v.0.48:
Puerco \Pu*er"co\, n. [Sp.] A hog. [1913 Webster] Puerco beds (Geol.), a name given to certain strata belonging to the earliest Eocene. They are developed in Northwestern New Mexico, along the Rio Puerco, and are characterized by their mammalian remains. [1913 Webster]